Chapter 29

Congenital Neutropenia

Christoph KleinDepartment of Pediatrics, Dr von Hauner Children’s Hospital, Ludwig-Maximilians-University Munich, Munich, Germany

Chapter OutlineIntroduction 605

Clinical Presentation 605

Differential Diagnosis and Laboratory Work-Up 606

Therapy and Outcome 608

Genetic Defects in Congenital Neutropenia 609

HCLS1-Associated Protein X-1 609

Neutrophil Elastase 609

GSD1b 610

G6PC3 Deficiency 610

GATA2 Deficiency 610

Hermansky-Pudlak Syndrome Type II 611

P14/LAMTOR2 Deficiency 611

Cohen Syndrome 611

VPS45 Deficiency 611

Specific Granule Deficiency 612

WHIM Deficiency 612

GFI1 613

WAS 613

Barth Syndrome 613

Shwachman-Diamond Syndrome 613

Clericuzio Neutropenia 614

Ethnic Neutropenia 614

Summary 614

Acknowledgments 615

References 615

INTRODUCTION

Congenital neutropenia comprises a heterogeneous group of

genetically determined disorders characterized by a

decrease of neutrophil granulocytes in the peripheral blood.

With the exception of the neonatal period and the first year

of life, neutrophil granulocyte counts in the peripheral blood

are not dependent on age. Neutropenia is defined as a con-

dition with an absolute neutrophil count of less than 1500

per microliter in individuals over 1 year of age, and less

than 2000 per microliter in the first year of life.1 In the new-

born period peripheral neutrophil counts depend on multiple

factors, such as prematurity and maternal stress.2

Neutropenia may be a persistent, sporadic/intermittent, or

cyclic trait (Table 29.1). Hematopoiesis generally follows a

cyclic pattern without any deleterious effects on health, and

can be evidenced in multiple hematopoietic lineages.

Intrinsic and/or extrinsic factors controlling physiological

waves of neutrophil production are poorly understood. In

cyclic neutropenia, peripheral neutrophil granulocyte counts

follow oscillatory patterns with nadirs every 2�3 weeks.

Severe congenital neutropenia is a rare disorder.

Several national and international registries exist,3 yet

comprehensive and reliable epidemiological surveys are

scarce. Based on primary immunodeficiency registries

in France and Iran, respectively, the population-based

prevalence of SCN appears to range from 0.77 to 6 per

million.4,5 The prevalence of genetic subtypes of SCN is

dependent on ethnicity.

CLINICAL PRESENTATION

Patients with severe congenital neutropenia develop

severe bacterial infections in the first year of life.

The risk of infection correlates with the degree and dura-

tion of neutropenia. The most frequently affected sites

of infections are the skin, and mucosal linings in the

oropharynx. Furthermore, bronchial and lung infections

are common. Patients with SCN are at risk for fatal sep-

sis. Periodontitis, gingivitis, and dental decay are frequent

clinical problems in SCN patients. Oral aphthae affecting

the tongue and buccal mucosa are frequent. Intestinal

inflammation mimicking inflammatory bowel disease

can be seen in patients with functional neutrophil

defects, including patients with congenital neutropenia.6,7

605K.E. Sullivan and E.R. Stiehm (Eds): Stiehm’s Immune Deficiencies. DOI: http://dx.doi.org/10.1016/B978-0-12-405546-9.00029-7

© 2014 Elsevier Inc. All rights reserved.

A characteristic feature of severe congenital neutropenia

is the lack of inflammatory infiltrates and pus in response

to bacterial infections. A large variety of Gram-positive

and Gram-negative bacterial organisms can be seen as

infectious agents, including Staphyloccus and

Streptococcus species, Pseudomonas species, and bacilli.

Deep-seated fungal infections (e.g., Aspergillus spp.,

Candida spp., mucormycosis) are usually seen only in

prolonged periods of neutropenia.

In addition to the broad spectrum of infectious dis-

eases, patients with SCN may present with other medical

problems. Many SCN patients have a predisposition to

bone fractures secondary to osteopenia.8,9 Furthermore,

defined genetic subgroups of congenital neutropenia may

present with other typical features (Figure 29.1); for

example, inner ear hearing loss may be seen in G6PC3

deficiency or GFI1 deficiency, and epilepsy and delayed

neurocognitive development can be seen in HAX1 defi-

ciency. Therefore, a comprehensive clinical survey of sys-

tems is mandatory in every patient with congenital

neutropenia.

DIFFERENTIAL DIAGNOSIS ANDLABORATORY WORK-UP

The diagnosis of congenital neutropenia relies on clinical

and hematological features. Before the diagnosis of con-

genital neutropenia can be established, it is important to

document the duration or persistent versus intermittent

nature of neutropenia by serial complete blood counts.

A single documentation of low neutrophil counts is not

sufficient. To monitor the oscillatory pattern of neutrophil

counts in patients with cyclic neutropenia, two to three

blood counts per week for 6 weeks are needed. Patients

with SCN often have increased absolute numbers of

monocytes and B cells, accompanied by hypergammaglo-

bulinemia. Furthermore, eosinophilia in bone marrow and

peripheral blood is often seen.

In children with isolated neutropenia without any

signs of severe infections, repeat blood counts following

4-week intervals may be sufficient. In this age group

immune-mediated neutropenia is by far the most common

cause of low neutrophil granulocyte counts, and usually

requires neither extensive work-up nor specific therapeu-

tic intervention. Autoimmune neutropenia occurs in the

context of viral infections, and is mostly caused by

TABLE 29.1 Classification of Congenital Neutropenia

Classification ANC Count

Mild neutropenia ANC 1000�1500/μl

Moderate neutropenia ANC 500�1000/μl

Severe neutropenia ANC, 500/μl

Persistent neutropenia ANC continuously ,1500/μl

Intermittent neutropenia ANC occasionally ,1500/μl

Cyclic neutropenia ANC with periodic oscillationsand nadir ,1000/μl

CN variant

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SCN-ELANE ELANESCN-GFI1 GFI1SCN-WAS WASSCN-HAX1 HAX1SCN-AK2 AK2GATA2 GATA2Glycogenosis Ib SLC37A4G6PC3 deficiency G6PC3Barth syndrome TAZSBDS SBDSCHH RBDSCHS LYST

GS type II RAB27A

HPS II AP3B1

P14 deficiency ROBLD3

VPS45 deficiency VSP45

Cohen syndrome COH1Poikiloderma with neutropenia (MPN1)

C16orf57

Neutropenia-CMT-II DNM2

FIGURE 29.1 Congenital neutropenia and

associated organ involvement.

606 PART | 2 Primary Immune Deficiencies

antibodies directed against FcRgIIIb or CD16.

Autoimmune neutropenia in children may last for several

months before spontaneous resolution occurs. Rarely,

autoimmune neutropenia in children can be seen in the

context of other signs of autoimmunity, such as in lupus

erythematosus or in conjunction with autoimmune hemo-

lytic anemia and thrombocytopenia (Evans syndrome).

In adult patients, autoimmune neutropenia is usually

characterized by longer duration and increased severity.

Adult neutropenia may be seen in various rheumatologi-

cal disorders, and is sometimes associated with clonal

proliferation of large granular lymphocytes (LGL).10 The

pathomechanisms of these variants of secondary neutro-

penia is poorly understood.

A special scenario occurs in neonatal alloimmune neu-

tropenia. Fetal granulocyte antigens (HNA1a, 1b, 1c, or

HNA-2A) encoded by paternal alleles may provoke a

maternal immune response. Specific IgG antibodies can

cross the placenta and cause neonatal neutropenia. This

disorder is usually self-limiting within 2�3 months.

Morphological assessment of stained peripheral blood

neutrophils and bone marrow progenitor cells is helpful to

clarify the etiology of congenital neutropenia, and is indi-

cated in patients with persistent neutropenia. Whenever

the differential diagnosis of a hematopoietic malignancy

is raised, a bone marrow puncture must be done without

delay. Morphological aberrations affecting the erythroid

or myeloid lineages or megakaryocytes can be indicative

of myelodysplastic syndromes, and require further cyto-

genetic and molecular investigations.

Pale neutrophils in bone marrow or peripheral blood

can reflect aberrant formation of granules as seen in spe-

cific neutrophil deficiency, which may present with con-

genital neutropenia. Pearson syndrome is caused by

mutations in mitochondrial DNA and often is associated

with vacuolization of progenitor cells. In classical SCN,

very few if any mature neutrophil granulocytes are seen

in the bone marrow. This phenotype has been termed

“maturation arrest” (Figure 29.2). However, not all var-

iants of congenital neutropenia are characterized by this

phenomenon. Patients with AP3B1 deficiency or P14/

LAMTOR2 deficiency show full maturation of neutrophil

granulocytes in the bone marrow. A preponderance of

mature and senescent neutrophil granulocytes is seen in

WHIM syndrome, in which morphological bone marrow

features are characterized by the term “myelokathexis.”

Depending on diagnostic considerations, additional

tests should be performed. Certified laboratories provide

assays to determine soluble and cell-bound anti-neutrophil

antibodies. Excess of zinc, deficiency of copper, and meta-

bolic disorders affecting the amino-acid metabolism can

easily be documented by serum and plasma analysis.

Abnormal values of serum trypsinogen and fecal elastase

as well as reduced levels of fat-soluble vitamins may point

to the diagnosis of pancreatic insufficiency, as seen in con-

genital neutropenia in Shwachman-Diamond syndrome.

Flow-based immunophenotyping studies should be

considered to screen for lymphoid deficiencies such as

BTK deficiency, NK cell deficiency, CD40L deficiency,

or combined B and T cell deficiencies, all of which have

been found in association with neutropenia. In STK4 defi-

ciency, congenital neutropenia has been associated with

hypergammaglobulinemia and progressive loss of naıve T

cells.11 Reticular dysgenesis is a variant of severe com-

bined immunodeficiency � in addition to defective T and

B cell differentiation, affected patients show congenital

neutropenia secondary to premature apoptosis of myeloid

progenitor cells, and inner ear hearing loss.12,13

In selected cases, specific experimental studies are

helpful to delineate aberrant differentiation and function

of neutrophil granulocytes. For example, ultramorphologi-

cal studies using transmission electron microscopy of

myeloid progenitor cells in the bone marrow and periph-

eral neutrophil granulocytes may document defective ER

structure or defective formation of electron-dense gran-

ules, respectively.14 Our own lab pursues novel ways to

define the global array of protein expression in healthy

and diseased neutrophil granulocytes.

Evidence of severe infections, a positive family history

or parental consanguinity, and persistence of low periph-

eral neutrophil counts in a child should alert the physician

to consider a genetic cause of congenital neutropenia.

Genetic diagnosis is desirable to guide patients with

respect to therapeutic options and genetic counseling.

However, despite extensive scientific investigations, the

genetic causes of congenital neutropenia remain enigmatic

in a considerable proportion. In these cases, scientific

collaboration with specialized centers is warranted to

FIGURE 29.2 Giemsa-stained bone marrow smear showing character-

istic myleoid maturation arrest.

607Chapter | 29 Congenital Neutropenia

facilitate progress in our understanding of these rare disor-

ders (see www.care-for-rare.org). Sequencing of exome-

enriched libraries of genome-wide sequencing has become

an important tool to discover novel genetic variants asso-

ciated with congenital neutropenia.

THERAPY AND OUTCOME

The mainstay of therapy for congenital neutropenia is to

prevent infectious complications. In cases of bacterial or

fungal infections, specific antibiotic coverage is manda-

tory. The choice of antimicrobial agents and the mode

of application have to be chosen based on the site and

severity of infection, and specific organisms and their

sensitivity and resistance profiles. Empiric coverage using

intravenous broad-spectrum beta-lactamase resistant peni-

cillins or cephalosporins is indicated in critically ill

patients. There is anecdotal evidence of the utility of allo-

geneic granulocyte transfusions in patients with severe

congenital neutropenia and severe infections. Modern

clinical management of patients with SCN is based on

administration of recombinant human G-CSF.15 Two ver-

sions of recombinant human G-CSF are in clinical use:

lenograstim is being produced in CHO cells, and filgras-

tim is being generated in Escherichia coli.16 A pegylated

version (pegfilgrastim) with a longer half-life is commer-

cially available, but due to certain disadvantages is not in

routine use in SCN patients. G-CSF is a glycosylated

cytokine with pleiotropic effects. G-CSF acts mainly on

hematopoietic stem and progenitor cells as well as on

neutrophil granulocytes, but effects on lymphoid cells and

non-hematopoietic cells such as neuronal stem cells, glial

cells, and retinal epithelial cells have been reported.17�19

Therapy with G-CSF is initiated at a dose of 3�5 μg/kgbody weight subcutaneously (SC). Most patients respond to

G-CSF at the indicated dose. A marked significant reduc-

tion in the risk of death by sepsis, from 50% during the first

year of life to a cumulative incidence of 8% at 10 years on

G-CSF therapy, has been reported.20 In those patients who

do not respond by an increase in peripheral neutrophil gran-

ulocyte counts, doses should be increased. If no response is

being seen at high doses of .50 μ/kg body weight, patients

are categorized as non-responders. The availability of

recombinant human G-CSF has markedly changed the life

expectancy and quality of life for patients with congenital

neutropenia.21 G-CSF is generally well tolerated; the most

common side effect is bone pain due to regenerative bone

marrow (in up to 5%). Occasionally, local or “flu-like”

reactions are seen, in less than 1% of patients. G-CSF

induced leukocytosis may be dangerous in defined condi-

tions such as sickle cell disease.22

However, long-term G-CSF application has been associ-

ated with more serious and life-threatening disorders: up to

25% of patients with severe congenital neutropenia develop

a clonal hematopoietic disorder such as MDS or acute

leukemia (Figure 29.3).23 Leukemic transformation has been

reported in patients with mutations in ELANE, HAX1,

WAS, SBDS, SLC37A4, and G6PC3.24�29 The pathophysi-

ology of leukemogenesis involves several factors, and in

addition to G-CSF administration both germline and acquired

somatic mutations play an important role. The most common

variant leukemia in SCN is acute myeloid leukemia (AML),

but acute lymphoid leukemia, juvenile myelomonocytic

leukemia (JMML), chronic myelomonocytic leukemia

(CMML), and bi-phenotypic leukemia have also been

observed. The most common cytogenetic aberration is

monosomy 7. In contrast to de novo cases of acute myeloid

leukemia, secondary leukemia in SCN patients have a dis-

tinct pattern of somatic mutations.30 Whereas de novo AML

cells often show mutations in tyrosine kinase genes (FLT3,

KIT, and JAK2), these mutations are not seen in patients

with secondary AML on the basis of SCN. In contrast, they

are often characterized by somatic mutations in the CSFR3

gene, affecting the intracytoplasmic part of the GCSF

receptor.

The risk of leukemogenesis appears to be even higher

in those patients who require high doses of G-CSF

(.8 μg/kg per day) to maintain protective neutrophil

counts. Defining molecular constituents of leukemogenic

development is a matter of active scientific investigations.

In view of an inherent risk for leukemogenesis, patients

with congenital neutropenia should be monitored closely.

Cytogenetic aberrations (e.g., monosomy 7) and molecular

markers (e.g., somatic mutations in CSF3R) may be indic-

ative of early preponderance of premalignant clones and

further evolution into hematological malignancies. Annual

bone marrow examinations are therefore warranted.

The only definitive cure for congenital neutropenia is

allogeneic hematopoietic stem cell transplantation.

Several groups have reported retrospectively their clinical

experience in small patient series.31 Currently, there is

consensus that failure to respond to G-CSF or the develop-

ment of MDS/leukemia is a strong indication for HSCT.

0.50

0.40

0.30

Cum

ulat

ive

inci

denc

e

0.20

0.10

0.00 5 10

Years on G-CSF15 20

Sepsis Death: Prior Data

Sepsis Death: Update

MDS/AML: Update

MDS/AML: Prior Data

FIGURE 29.3 Cumulative incidence of MDS/AML and sepsis in con-

genital neutropenia. Reproduced from Rosenberg et al.,23 rJohn Wiley

& Sons (2010), with permission.

608 PART | 2 Primary Immune Deficiencies

Some authors suggest that high-risk patients (patients

requiring high doses of G-CSF (. 8 μg/kg per day), with

molecular or cytogenetic evidence of clonal aberrations

(G-CSF receptor mutations), or with the Gly185Arg muta-

tion in the ELANE gene should strongly be considered for

allogeneic HSCT. Better molecular HLA-typing and donor

selection, prevention of graft-versus-host disease, and sup-

portive care may reduce the threshold for recommending

allogeneic stem cell transplantation even for patients who

do not meet the above criteria.32 However, non-HLA iden-

tical HSCT is reserved for high-risk patients. The com-

bined overall and event-free survival (EFS) rates for

patients transplanted without malignant transformation are

excellent, at 89% and 75%, respectively.31 The source of

hematopoietic stem cells is quite diverse, including HLA-

matched and HLA-mismatched cells from bone marrow,

mobilized peripheral blood HSC, and umbilical cord blood

cells. Most conditioning regimens are based on myeloabla-

tive protocols using busulfan and cyclophosphamide (plus

anti-thymocyte globulin). Reduced intensity regimens

based on fludarabine have also been used successfully.

The success rate of allogeneic HSCT in patients with sec-

ondary MDS/leukemia is inferior. Cumulative survival

rates of all published patients reveal estimated EFS rates

of 27% to 57% for patients with leukemia and MDS,

respectively.31

In view of the limited experience, no evidence-based

guidelines can be proposed. It can be stated however, that

life-expectancy and quality of life has markedly been

improved with the introduction of G-CSF therapy and the

refinement of allogeneic HSCT procedures. Future studies

are needed to further define risk factors and rational strat-

ification of therapeutic choices for individual patients and

to determine the potential value of novel therapeutic strat-

egies such as HSC gene therapy.

GENETIC DEFECTS IN CONGENITALNEUTROPENIA

Just a few years ago, the clinical diversity of congenital

neutropenia disorders had only been incompletely appre-

ciated. With increasing knowledge of the underlying

genetic mutations, however, clinicians can now help their

patients in multiple ways, such as by facilitating genetic

counseling and early molecular diagnosis, defining spe-

cific risk factors and raising awareness of involvement of

other organ systems.

HCLS1-Associated Protein X-1(OMIM #610738)

Rolf Kostmann, a Swedish pediatrician, is acclaimed for

the first clinical description of severe congenital

neutropenia.33,34 In his landmark papers he reported

salient features of this rare disease transmitted in an auto-

somal recessive inheritance pattern: affected patients had

very low neutrophil granulocytes and died within the first

years of life secondary to acute bacterial infections and

sepsis. Morphological analyses of stained bone marrow

smears revealed an early arrest of physiological matura-

tion of neutrophil granulocytes at the stage of promyelo-

cytes. To date, this feature remains a morphological

hallmark for severe congenital neutropenia. In 2007, the

molecular etiology of Kostmann disease, a term now con-

fined to a particular genetically defined subtype of SCN,

was determined, and loss-of-function mutations in HAX1

(HCLS1-associated protein X-1) were discovered.26

HAX1 is a cytosolic protein and controls a variety of cel-

lular functions, including maintenance of cellular viability

via stabilization of the mitochondrial membrane potential.

The detailed mechanism of actions is still not completely

understood. HAX1 has been implicated in various other

pathways, including cell migration and trafficking of

intracellular transporter molecules, RNA metabolism, and

defense against viral infections.35 Interestingly, at least

two transcripts of the HAX1 gene (encoding isotype A

and isotype B) have been identified which are of rele-

vance to the disease phenotype. Isotype A is widely

expressed, and isotype B is predominantly found in

neuronal cells. In cases where the mutations affect only

isotype A but not isotype B, HAX1 deficiency manifests

as isolated severe congenital neutropenia. In cases where

the mutations affect both isoforms, patients suffer from

SCN in association with variable neurological features,

ranging from mild cognitive dysfunction to progressive

devastating neurodegeneration. Congenital neutropenia in

HAX1 deficiency is responsive to G-CSF therapy. There

is no cure for neuronal apoptosis in the central nervous

system.

Neutrophil Elastase (OMIM #162800,202700)

The chapter of genetics in CN research was opened in

1999, when the teams of Marshall Horwitz and David

Dale identified a molecular defect first in patients with

cyclic neutropenia,36 and subsequently in SCN.37 Using a

genome-wide linkage analysis approach in 13 families

with cyclic neutropenia, heterozygous mutations in the

gene encoding neutrophil elastase (ELANE [ELA2-

neutrophil expressed]) were described. Cyclic neutrope-

nia, in contrast to SCN, describes an oscillatory change

of absolute neutrophil counts following 3-week cycles.

In nadir phases, patients may be prone to bacterial infec-

tions. Therapeutic interventions are often not needed in

cyclic neutropenia, yet some patients benefit from prophy-

lactic antibiotic therapy and GCSF can shorten/abrogate

609Chapter | 29 Congenital Neutropenia

recurrent periods of neutropenia. Some patients with

cyclic neutropenia eventually may progress to severe con-

genital neutropenia. The expression of neutrophil elastase

is restricted to myeloid cells. Initially produced at the

promyelocyte stage, the protein is later packaged within

primary (azurophilic) granules in mature neutrophils.38

Neutrophil elastase is released upon exposure of the neu-

trophil to inflammatory stimuli, and plays a critical role in

antibacterial killing. In the extracellular environment, neu-

trophil elastase cleaves extracellular matrix proteins,

while serpins (such as α1-proteinase inhibitor) antagonize

the proteinase activity. In addition, neutrophil elastase has

emerged as a critical regulator of inflammation by virtue

of its capacity to proteolytically modify cytokines and

chemokines such as CXCL12, TNF-α, and IL-6, as well

as cell surface receptors.39

Mutations in ELANE are found in approximately 50%

of Caucasian CN patients.40,41 So far, more than 100

mutations in ELANE have been identified in patients with

SCN or cyclic neutropenia.42,43 Mutated ELANE in

patients with SCN acts as a dominant-negative factor.

ELANE mutations can be acquired or transmitted in an

autosomal dominant inheritance pattern.44 A number of

families with somatic mosaicism have also been

reported.45,46 SCN associated with mutations in ELANE

can be categorized as proteopathy. The disease mecha-

nism involves increased endoplasmic reticulum stress due

to misfolding of an aberrant neutrophil elastase protein

and consecutively premature apoptosis of myeloid pro-

genitor cells.47,48There are other mutually non-exclusive

explanations of how ELANE mutations may cause neutro-

penia � for example, by interfering with retinoic acid

receptor controlled myeloid cell differentiation.49

Most patients with mutations in ELANE respond to

recommended doses of GCSF, yet some patients require

high-dose GCSF therapy or may even not respond at all. In

comparison to CN patients without mutations in ELANE,

the frequency of somatic CSF3R mutations and malignant

transformation appears to be higher in CN patients with

ELANE mutations.38,43 However, this effect has not held

true in all surveys.24 A particularly severe clinical course is

seen in patients with the Gly185Arg mutation.24,38

GSD1b (OMIM #232220)

Glycogen storage disease type 1b (GSD1b) is caused by

mutations in the gene SLC37A4, encoding glucose-6-

phosphate translocase (G6PT), a protein with critical

importance to shuttle G6P from cytosol into the endo-

plasmic reticulum. In contrast to glycogen storage dis-

ease type 1a (GSD1a), defined by glycogen storage and

hypoglycemia secondary to deficiency of glucose-

6-phosphatase (encoded by the gene G6PC1), GSD1b,

which shares the metabolic features of GSD1a, is also

characterized by susceptibility to bacterial infections due

to congenital neutropenia. Furthermore, GSD1b may be

associated with other findings, such as liver adenomas,

nephropathy, bone mineral density defect, polycystic ova-

ries, short stature, or inflammatory bowel disease.

G6PC3 Deficiency (OMIM #612541)

The ubiquitously expressed enzyme G6PC3, a paralog of

G6PC1, controls energy homeostasis in the endoplasmic

reticulum. Patients with mutations in G6PC3 suffer from

congenital neutropenia and additional complex develop-

mental aberrations, such as structural heart defects or

developmental aberrations of the urogenital system.14

Furthermore, bone abnormalities, inner ear hearing loss,

and cutaneous prominence of veins, presumably due to

decreased subcutaneous fat tissue, have been noted. The

phenotypic variability may also include hypothyroidism

and facial dysmorphism.50 Usually, patients have myeloid

maturation arrest morphologically indistinguishable from

other molecular causes of SCN. Rarely, however, they

may present with abundant neutrophils in the bone mar-

row, and features suggestive of myelokathexis.51 Other

hematological features include mild transient and perma-

nent thrombocytopenia.52 G6PC3 deficiency can also

result in isolated non-syndromic severe neutropenia.

The pathophysiology of G6PC6 deficiency involves

increased ER stress, as evidenced by increased levels

of BiP expression and ultrastructural changes in ER

morphology.14 As a consequence, G6PC3-deficient neutro-

phils show an enhanced propensity to undergo apoptosis.

The discovery of human G6PC3 deficiency has shed light

on the role of glucose metabolism in neutrophil granulo-

cytes. Nevertheless, despite the obvious functional links,

the stoichiometric and biochemical relationships between

G6PT, G6PC1, and G6PC3 remain to be resolved.

Patients with disorders in G6PC3 and glucose-6-

phosphate translocase require multidisciplinary care. From a

hematological perspective, congenital neutropenia responds

to low-dose G-CSF and is less likely to evolve into leukemia

when compared to other genetic SCN subtypes.

GATA2 Deficiency (OMIM #614172,614038, 601626, 614286)

A familial disposition to acute myeloid leukemia and mye-

lodysplastic syndromes can be inherited as an autosomal

dominant trait. Genetic studies revealed mutations in

the transcription factor genes RUNX1 (familial platelet

disorder and predisposition to AML) and CEBPA.53 More

recently, mutations in GATA2 were identified in indivi-

duals with a predisposition to AML.54,55 Germline muta-

tions in GATA2 may manifest clinically as “MonoMAC

syndrome” (monocytopenia, B- and NK-cell lymphopenia,

610 PART | 2 Primary Immune Deficiencies

myelodysplasia, cytogenetic abnormalities, pulmonary

alveolar proteinosis, and myeloid leukemias)56 or

“Emberger syndrome” (sensory deafness, lymphedema,

cytopenia, AML).57 An analysis in the French SCN regis-

try showed that GATA2 mutations are also seen in a sub-

group of patients with chronic neutropenia.58 Thus, in this

rare and newly defined patient group, isolated chronic neu-

tropenia may evolve into MonoMAC syndrome and AML.

A fundamental biological feature of neutrophil granu-

locytes is their capacity to store and secrete toxic proteins

and to generate phagolysosomes by fusing membrane

structures to kill ingested microbes. Several monoge-

netic defects affecting vesicular trafficking and various

membrane compartments have been discovered in patients

presenting with congenital neutropenia. These defects pro-

vide evidence that the function of neutrophil granulocytes

is extensively influenced by the processes of endocytosis

and exocytosis, governing internalization of nutrients,

membrane-associated molecules and pathogens, intracellu-

lar signaling, and recycling of membrane proteins.

Hermansky-Pudlak Syndrome Type II(OMIM #608233)

Hermansky-Pudlak syndrome comprises a heterogeneous

group of disorders characterized by platelet dysfunction,

tyrosinase-positive oculocutaneous albinism, and, occasion-

ally, interstitial lung disease, pulmonary fibrosis, and

inflammatory colitis.59 Among the currently known eight

distinct molecular subtypes, only type II is associated with

congenital neutropenia. HPS type II is caused by mutations

in the AP3B1 gene encoding the beta chain of the adaptor

protein-3 (AP3) complex.60 AP-3 is critically involved in

the biogenesis of specialized endosomal organelles referred

to as lysosome-related organelles. Nevertheless, ultrastruc-

tural and functional studies in neutrophil granulocytes could

not show any specific defect in neutrophil granulocytes.61

HPS-II patients show additional defects in cytotoxic NK

and T cells, as well as low numbers of NKT cells. In con-

trast to other well-defined monogenetic diseases associated

with defects of cytotoxic lymphocytes, a clinically relevant

risk of hemophagocytosis could not be established in

patients with Hermansky-Pudlak syndrome type II.62 Thus,

in comparison to other known defects of cytotoxicity and

neutropenia syndromes, the hematological and immunologi-

cal features are relatively mild. Neither long-term G-CSF

therapy nor allogeneic hematopoietic stem cell transplanta-

tion are warranted.

P14/LAMTOR2 Deficiency (OMIM #610798)

P14/LAMTOR2 deficiency is a disorder characterized by

congenital neutropenia, growth failure, hypopigmentation,

and combined lymphoid dysfunction.63 In contrast to

severe congenital neutropenia, morphology of the bone

marrow is not characterized by myeloid maturation arrest

but rather by hypercellularity and increased abundance of

myeloid cells, including mature neutrophils. This disease

is caused by defective expression of the endosomal adap-

tor protein p14/LAMTOR2, resulting in aberrant subcellu-

lar distribution of late endosomes and aberrant endosomal

signal pathways.63 Signal transduction via the GCSF

receptor is markedly reduced, whereas signal transduction

via the GMCSF receptor is enhanced. The latter phenome-

non explains myeloid hypercellularity in the bone marrow,

often associated with bone pains. The only curative

therapy is allogeneic bone marrow transplantation, yet

experience is limited. Increased production of proinflam-

matory cytokines such as TNF-α may increase the risk of

graft rejection, and has to be taken into consideration.64

Cohen Syndrome (OMIM #216550)

Vacuolar proteins for sorting (VPS) are ATPases required

for endosomal trafficking and protein recycling through

the trans-Golgi network. Cohen syndrome is caused by

mutations in COH1/VPS13B.65 VPS13B is a peripheral

Golgi membrane protein required to maintain the integrity

of Golgi ribbon.66

In addition to intermittent neutropenia, clinical fea-

tures of Cohen syndrome consist of a combination of

mental retardation, facial dysmorphism, postnatal micro-

cephaly, muscular hypotonia, joint laxity, and progressive

chorioretinal dystrophy.67 Therapeutic interventions are

limited to supportive care; rare patients with recurrent

bacterial infections may benefit from GCSF. Since the

COH1 gene covers an 864-kb genomic region and

the transcript is composed of 14,093 nucleoteides, genetic

diagnosis is not trivial and should be limited to those

cases in which genetic counseling is desired. In the

absence of chorioretinal dystrophy or neutropenia in

patients lasting over 5 years, the likelihood of finding

mutations in VPS13B is extremely low.68

VPS45 Deficiency (OMIM #615285)

A rare disorder with mutations in vacuolar sorting protein

(VPS)-45 has been described in several Middle Eastern

families.69

VPS45, a highly conserved protein associated with cel-

lular membranes, including those of the Golgi, endosomes,

and other vesicles, is a member of the Sec1p/Munc18-like

(SM) family that binds soluble N-ethylmaleimide-sensitive

factor attachment protein receptors. Affected children

present with severe congenital neutropenia, progressive

bone marrow fibrosis, and nephromegaly secondary to

extramedullary hematopoiesis.69,70 VPS45 interacts with

Rabenosyn-5, beta1-integrin, and syntaxin-16, and

611Chapter | 29 Congenital Neutropenia

regulates membrane trafficking in the endosomal system.

VPS45-deficiency affects both viability of neutrophil gran-

ulocytes and LFA-1-dependent migration. Response to

G-CSF is non-satisfactory; the only curative therapy is

allogeneic stem cell transplantation.

Specific Granule Deficiency(OMIM #245480)

Specific granule deficiency is an ultra-rare congenital dis-

order characterized by defective expression of proteins

in specific granules and associated functional defects in

neutrophil granulocytes.71,72 Neutrophil granulocytes lack

expression of secondary granule proteins (Figure 29.4)

and defensins, and have abnormalities in neutrophil

migration and disaggregation, atypical nuclear morphol-

ogy, and impaired bactericidal activity.73 Affected

patients suffer from indolent and smoldering skin

infections, and the clinical course is often complicated by

deep-sited infections of lungs or mastoids. Congenital

neutropenia is not a constant finding in patients with

specific granule deficiency, but patients with intermit-

tent neutropenia71,72 or severe neutropenia74 have been

described.

Based on the clinical, morphological, and functional

findings in a murine model lacking expression of the tran-

scription factor CCAAT/enhancer binding protein epsilon

(C/EBPE),75 Lekstrom-Himes et al. hypothesized that the

C/EBP epsilon gene may be mutated in patients with spe-

cific granule deficiency, and identified the first patient

with mutations in C/EBPE.76 However, not all patients

with specific granule deficiency show mutations in

C/EBPE. Other genetic factors are currently under

investigation.

WHIM Deficiency (OMIM #193670)

WHIM (warts, hypogammaglobulinemia, immunodefi-

ciency, myelokathexis) is an inherited immune deficiency

characterized by neutropenia, B cell lymphopenia, myelo-

kathexis, hypogammaglobulinemia, recurrent infections,

and a marked susceptibility to human papilloma virus

infection. A review on 37 patients published in the litera-

ture documented that the disease manifested in all

patients in early childhood.77 They suffered from recur-

rent infections, including pneumonias, sinusitis, cellulitis,

urinary tract infection, thrombophlebitis, omphalitis, oste-

omyelitis, deep soft-tissue abscesses, and skin infections.

Thus, neutropenia-related infections precede later compli-

cations by human papillomavirus infections leading to

warts, condyloma acuminata, and invasive mucosal carci-

nomas. In contrast to patients with severe congenital neu-

tropenia, the bone marrow of WHIM patients is

characterized by abundance of hyper-mature, senescent,

and apoptotic neutrophil granulocytes, a condition known

as “myelokathexis.”

The majority of patients with WHIM syndrome have

monoallelic (truncating) mutations in the CXCR4 gene,

leading to hyperresponsiveness of CXCR4-expressing

cells towards its cognate ligand CXCL12/SDF1.78 The

altered CXCR4/CXCL12 interaction is associated with

impaired cellular homeostasis and trafficking, resulting in

immunological dysfunctions of B cells and myeloid cells.

Therapeutic measures include administration of G-CSF,

intravenous immunoglobulins, and antibiotic prophylaxis.

Based on insights into the pathophysiological mechan-

isms, a new therapeutic strategy has been proposed. The

macrocyclic compound and bicyclam derivative plerixa-

for (Mozobils) is a potent antagonist of CXCR4. Initially

developed to inhibit HIV infection, the drug has

FIGURE 29.4 Transmission electron microscopy of neutrophil granulocytes from patient with specific granule deficiency due to mutations in C/

EPBE. Sg, specific granules; Ag, azurophil granules; Rer, rough endoplasmic reticulum; Go, Golgi apparatus; Mi, mitochondria. Reproduced from

Breton-Gorius et al.,73 r Elsevier (1980), with permission.

612 PART | 2 Primary Immune Deficiencies

subsequently been used extensively to accelerate release

of hematopoietic stem cells from the bone marrow into

the peripheral blood. Recent clinical studies have

highlighted its capacity to attenuate the phenotype in

WHIM patients.79,80

GFI1 (OMIM #607847, 613107)

Heterozygous mutations in GFI1 (growth factor indepen-

dence-1) have been identified in patients with SCN81 and

cyclic neutropenia.82 GFI1-mutant patients have increased

numbers of monocytes and reduced numbers of CD4-T

cells and B cells. Both in engineered Gfi1-knockout mice

and in a murine mutagenesis screen, Gfi1 has emerged as

a critical factor for granulopoiesis.81,83

GFI1 is a zinc-finger protein acting as transcription

factor governing hematopoietic stem cell self-renewal and

differentiation, in particular with respect to myeloid cell

differentiation. Gfi1 interacts with various target genes

which include genes critical for myeloid cell differentia-

tion such as ELANE, CEBPε, CEBPα, HoxA9, Pbx1, andMeis1.35 Furthermore, GFI1 has been shown to interact

with BAX, implicating a role in regulation of apoptosis

and a variety of microRNAs, including miR-21, miR-

196b, and miR-96. Based on extensive studies in murine

model systems, Gfi1 has emerged as a major orchestrating

factor for hematopoietic stem cell differentiation.

WAS (OMIM #300299)

Inactivating mutations in the Wiskott-Aldrich syndrome

(WAS) gene cause Wiskott-Aldrich syndrome, an X-

linked disorder characterized by immunodeficiency, auto-

immunity, microthrombocytopenia, and bleeding diathe-

sis, as well as predisposition to malignant lymphoma. The

corresponding gene product (WAS protein) is critically

involved in rearrangement of the actin cytoskeleton.

Defective actin remodeling causes a wide spectrum of

cellular dysfunction in various subsets of leukocytes, such

as leukocye migration and chemotaxis, T-cell receptor-

mediated signal transduction, and formation of the NK

cell immunological synapse. However, not only loss-of-

function mutations but also gain-of-function mutations

can cause disease. Constitutively active WASP (such as

L270P or I294T) disables the autoinhibitory state.

Interestingly, these molecular variants cause a phenotype

of severe congenital neutropenia with maturation arrest.

Furthermore, affected patients may have lymphopenia.

The WASP I294T variant causes increased and deloca-

lized actin polymerization followed by defective cytoki-

nesis, increased apoptosis, and susceptibility to

myelodysplasia and leukemia. Therefore, as in other

genetic variants of SCN predisposing to leukemia,

patients should be monitored closely. Yearly bone

marrow exams are warranted. G-CSF can reverse neutro-

penia and may used cautiously. Definitive cure requires

allogeneic HSCT.

Barth Syndrome (OMIM #302060)

Barth syndrome is a rare complex disorder characterized

by cardiomyopathy (dilated or hypertrophic, associated

with left ventricular non-compaction or endocardial

fibroelastosis), skeletal muscle weakness, growth delay,

and low neutrophil granulocyte counts. Neutropenia can

be constant, intermittent, or cyclic. The diagnosis can be

confirmed by analysis of 3-methylglutaconic aciduria.84

Barth syndrome is caused by mutations in the ubiquitously

expressed gene TAZ, which encodes tafazzin, a mitochon-

drial acyltransferase involved in cardiolipin metabolism.85

Tafazzin-deficient cells show reduced mature cardiolipin

levels and increased levels of monolysocardiolipin. The

pathophysiology of neutropenia is not fully understood;

increased clearance of neutrophils by tissue macrophages

has been proposed as one potential mechanism.86 A recent

survey reported a 5-year survival rate of 70% for patients

born after 2002.87 Cardiomyopathy and infections are life-

threatening complications. Early diagnosis and rapid inter-

disciplinary interventions are needed to further improve

survival and quality of life.

Shwachman-Diamond Syndrome(OMIM #607444)

Shwachman-Diamond syndrome (SDS) is an autosomal

recessively inherited bone marrow-failure syndrome origi-

nally characterized by neutropenia and pancreatic dys-

function.88,89 Further studies documented that the

hematopoietic defect is not confined to neutropenia, but

may also involve red blood cells and platelets. SDS is

associated with a significant risk of aplastic anemia and

malignant transformation. Multiple additional organ sys-

tems, including the pancreas, liver, heart, bones, and cen-

tral nervous system, can also be affected. Mutations in

the Shwachman-Bodian-Diamond syndrome (SBDS) gene

are found in approximately 90% of patients.90 SBDS has

been implicated in multiple biologic processes, including

ribosome biogenesis, stabilization of the mitotic spindle,

and cell motility.

The observation of defective assembly of ribosomes in

SBDS-deficient cells has raised the idea that SDS may be

part of a growing family of ribosomopathies.91 Recent

work in Dictyostlium discoideum and human cells has

provided compelling evidence that SBDS plays a critical

role for ribosome function.91 Upon physical interaction of

SBDS and the GTPase elongation factor-like 1 (EFL1) on

nascent 60 S subunits, the ribosome anti-association fac-

tor eukaryotic initiation factor 6 (eIF6) is expelled from

613Chapter | 29 Congenital Neutropenia

the protein complex. In the absence of SBDS, the physio-

logical prerequisite for the translational activation of ribo-

somes is perturbed.90

Patients with SDS require interdisciplinary and multi-

modal care. Pancreatic enzymes and fat-soluble vitamin

supplementation are indicated in patients with exocrine

pancreatic insufficiency. In patients with severe neutro-

penia and/or recurrent infections, G-CSF therapy should

be considered. However, SDS is associated with a high

risk of malignant transformation, and therefore surveil-

lance is critical. Allogeneic HSCT remains the only cura-

tive modality for hematopoietic defects, and is indicated

in patients with bone marrow failure and malignancies.

Reduced intensity conditioning regimens should be used,

since standard myeloablative conditioning regimens have

been associated with severe and life-threatening side

effects.92,93

Clericuzio Neutropenia (OMIM #604173)

A rare genodermatosis associating poikiloderma (irregular

skin coloration/pigmentation) and neutropenia (PN) was

originally reported by Clericuzio et al. in Navajo kindreds

and discussed by Erickson.94 This autosomal recessive syn-

drome is characterized by onset of a papular erythematous

rash, pigment anomalies, telangiectasia, and hyperkeratosis.

In addition to the skin involvement, it is characterized by

neutropenia, short stature, pachyonychia (nail dystrophy),

and pulmonary disease. Approximately half of the patients

also have abnormalities in red blood cell and/or platelet

counts, indicative of a more global haematopoietic defect.

Myelodysplasia has been reported.95 These clinical symp-

toms suggest an overlap with other rare disorders such as

dyskeratosis congenita (DC) and Rothmund-Thomson syn-

drome (RTS), both associated with impaired genomic

integrity. PN is caused by mutations in the C16Orf57

gene,96 which codes for the protein hMPN1, alias USB1,

an RNA exonuclease that processes the spliceosomal U6

small nuclear RNA (snRNA) post-transcriptionally.97�99 It

is still unknown how defective processing of the U6 RNA

spliceosome component causes disease. Even though telo-

meres were not found to be short in PN patients, it is possi-

ble that aberrant function of telomeres, which cap and

protect the ends of chromosomes, may be a common fea-

ture of DC, RTS, and PN.

Ethnic Neutropenia (OMIM #611862)

By far the largest group of individuals with decreased

neutrophil counts does not require any further diagnostic

or therapeutic medical intervention. Some ethnic groups

in the Middle East and Africa have lower neutrophil

counts. Since this condition does not predispose to infec-

tions, the term benign ethnic neutropenia has been

proposed. Morphology of bone marrow and neutrophil

function in these individuals is normal. Genetic studies

have highlighted a polymorphism in the gene encoding

the Duffy antigen receptor for chemokines (DARC).100,101

The Duffy Null (Fy2) polymorphism (SNPrs2814778) is

associated with protection against Plasmodium vivax

malaria infection. Since the receptor is used by

Plasmodium vivax to enter erythrocytes,102 individuals

with two of the null alleles of the Duffy antigen are resis-

tent to Plasmodium vivax infection. The same polymor-

phism has been associated with the phenotype of ethnic

neutropenia.100,101

The Duffy antigen is expressed on red blood cells,

and capillary and post-capillary venular endothelial

cells. Myeloid cells do not express DARC receptor.

DARC is thus unlikely to display intrinsic effects on

neutrophil granulocytes, but has been shown to be

involved in transendothelial migration of neutrophil

granulocytes.103 In a murine DARC knockout model sys-

tem, interleukin-8/CXCL8 driven chemotaxis of neutro-

phils into infected lung tissue was reduced.104 Despite

these intriguing findings, the exact mechanisms explain-

ing reduced neutrophil counts associated with the DARC

polymorphism remain unknown. Many individuals

homozygous for the Duffy null alleles (Fy2) have neu-

trophil counts comparable to normal levels in the

Caucasian population. Therefore, more studies, includ-

ing documentation of potential oscillations, are needed

to shed light on the role of DARC in determining periph-

eral neutrophil counts.

SUMMARY

In addition to the genetic subtypes of congenital neutrope-

nia presented above, a variety of other monogenetic

defects has been shown to be associated with neutropenia.

These nosological entities are listed in Box 29.1, but are

not discussed in detail in this chapter. Interested readers

are referred to more specialized literature.

In summary, clinical and translational research activi-

ties around the globe have highlighted an unexpected

diversity of genetic factors and fundamental pathways

controlling the differentiation, maintenance, and decay of

neutrophil granulocytes. An increasing body of knowl-

edge is not only relevant for individualized diagnostic

and therapeutic advice for patients and their families, but

also for the scientific community in general.

Nevertheless, many questions remain unanswered, and in

many patients with congenital neutropenia the underlying

mutations are not known. The discovery of novel path-

ways controlling the life and death of neutrophil granulo-

cytes may open new horizons for the development of

novel therapies.

614 PART | 2 Primary Immune Deficiencies

ACKNOWLEDGMENTS

I am grateful to all members of the Care-for-Rare Alliance for shar-

ing clinical data and biological samples, the International SCN regis-

tries for support, and all patients and their families for participating

in genetic studies. This work was partially supported by grants from

the European Research Council, the German Research Foundation,

the German Federal Ministry of Education and Research, and the

Care-for-Rare Foundation.

REFERENCES

1. Manroe BL, Weinberg AG, Rosenfeld CR, Browne R. The neonatal

blood count in health and disease. I. Reference values for neutro-

philic cells. J Pediatr 1979;95(1):89�98.

2. Schelonka RL, Yoder BA, Hall RB, et al. Differentiation of

segmented and band neutrophils during the early newborn period.

J Pediatr 1995;127(2):298�300.

3. Dale DC, Bolyard AA, Schwinzer BG, et al. The Severe Chronic

Neutropenia International Registry: 10-year follow-up report.

Support Cancer Ther 2006;3(4):220�31.

4. Group CTFPs. The French national registry of primary immunodefi-

ciency diseases. Clin Immunol 2010;135(2):264�72.

5. Rezaei N, Aghamohammadi A, Moin M, et al. Frequency and clini-

cal manifestations of patients with primary immunodeficiency disor-

ders in Iran: update from the Iranian Primary Immunodeficiency

Registry. J Clin Immunol 2006;26(6):519�32.

6. Davis MK, Rufo PA, Polyak SF, Weinstein DA. Adalimumab for

the treatment of Crohn-like colitis and enteritis in glycogen storage

disease type Ib. J Inherit Metab Dis 2008. [Epub ahead of print.

PMID: 18172743]

7. Begin P, Patey N, Mueller P, et al. Inflammatory bowel disease and

T cell lymphopenia in G6PC3 deficiency. J Clin Immunol 2013;

33(3):520�5.

8. Yakisan E, Schirg E, Zeidler C, et al. High incidence of significant

bone loss in patients with severe congenital neutropenia

(Kostmann’s syndrome). J Pediatr 1997;131(4):592�7.

9. Elhasid R, Hofbauer LC, Ish-Shalom S, et al. Familial severe con-

genital neutropenia associated with infantile osteoporosis: a new

entity. Am J Hematol 2003;72(1):34�7.

10. Pontikoglou C, Kalpadakis C, Papadaki HA. Pathophysiologic

mechanisms and management of neutropenia associated with large

granular lymphocytic leukemia. Expert Rev Hematol 2011;4

(3):317�28.

11. Abdollahpour H, Appaswamy G, Kotlarz D, et al. The phenotype

of human STK4 deficiency. Blood 2012;119(15):3450�7.

12. Pannicke U, Honig M, Hess I, et al. Reticular dysgenesis (aleuko-

cytosis) is caused by mutations in the gene encoding mitochondrial

adenylate kinase 2. Nat Genet 2009;41(1):101�5.

13. Lagresle-Peyrou C, Six EM, Picard C, et al. Human adenylate

kinase 2 deficiency causes a profound hematopoietic defect asso-

ciated with sensorineural deafness. Nat Genet 2009;41

(1):106�11.

14. Boztug K, Appaswamy G, Ashikov A, et al. A syndrome with con-

genital neutropenia and mutations in G6PC3. N Engl J Med

2009;360(1):32�43.

15. Bonilla MA, Gillio AP, Ruggeiro M, et al. Effects of recombinant

human granulocyte colony-stimulating factor on neutropenia in

patients with congenital agranulocytosis. N Engl J Med 1989;320

(24):1574�80.

16. Welte K, Gabrilove J, Bronchud MH, Platzer E, Morstyn G.

Filgrastim (r-metHuG-CSF): the first 10 years. Blood 1996;88

(6):1907�29.

17. Liu H, Jia D, Fu J, et al. Effects of granulocyte colony-stimulating

factor on the proliferation and cell-fate specification of neural stem

cells. Neuroscience 2009;164(4):1521�30.

18. Wang J, Yao L, Zhao S, et al. Granulocyte-colony stimulating fac-

tor promotes proliferation, migration and invasion in glioma cells.

Cancer Biol Ther 2012;13(6):389�400.

Box 29.1 Differential Diagnosis of Congenital Neutropenia

� Acquired conditions� Autoimmune neutropenia� Alloimmune neutropenia� Nutritional defects (copper deficiency, zinc intoxication)� Drug-induced neutropenia (metamizol, chloramphenicol,

benzenes, etc.)� Myelodysplastic syndromes� Primary genetic defects of neutrophil granulocytes

associated with neutropenia� ELANE� HAX1� G6PC3� CSFR3� GFI1� WAS� P14/LAMTOR2� VPS45

� HPS2� Genetically undefined (severe) congenital neutropenia� Monogenetic conditions affecting primarily cells other

than neutrophil granulocytes with associated neutropenia� Metabolic diseases of amino acids (methylmalonic acide-

mia, 3-methylglutaconic aciduria)� Nephropathy (Finnish type) (nephrin deficiency, NPHS1)� Bone marrow failure syndromes (SBDS, telomere

deficiencies)� MonoMAC syndrome (GATA2)� Primary immunodeficiencies (SCID, BTK, CD40L, STK4,

CHS, GS)� Cartilage-hair hypoplasia (RMRP)� Charcot-Marie-Tooth disease (DNM2)� Barth syndrome (TAZ)� Cohen disease (COH)� Ethnic neutropenia (DARC)

615Chapter | 29 Congenital Neutropenia

19. Khera S, Tiwari A, Srinivasan R, Gupta A, Luthra-Guptasarma M.

Expression of granulocyte colony stimulating factor and its receptor

by retinal pigment epithelial cells: a role in maintaining

differentiation-competent state. Curr Eye Res 2011;36(5):469�80.

20. Rosenberg PS, Alter BP, Bolyard AA, et al. The incidence of leu-

kemia and mortality from sepsis in patients with severe congenital

neutropenia receiving long-term G-CSF therapy. Blood 2006;107

(12):4628�35.

21. Zeidler C, Welte K. Hematopoietic growth factors for the treatment

of inherited cytopenias. Semin Hematol 2007;44(3):133�7.

22. Wali Y, Beshlawi I, Fawaz N, et al. Coexistence of sickle cell dis-

ease and severe congenital neutropenia: first impressions can be

deceiving. Eur J Haematol 2012;89(3):245�9.

23. Rosenberg PS, Zeidler C, Bolyard AA, et al. Stable long-term

risk of leukaemia in patients with severe congenital neutropenia

maintained on G-CSF therapy. Br J Haematol 2010;150

(2):196�9.

24. Rosenberg PS, Alter BP, Link DC, et al. Neutrophil elastase muta-

tions and risk of leukaemia in severe congenital neutropenia. Br J

Haematol 2008;140(2):210�13.

25. Germeshausen M, Ballmaier M, Welte K. Incidence of CSF3R

mutations in severe congenital neutropenia and relevance for leuke-

mogenesis: Results of a long-term survey. Blood 2007;109

(1):93�9.

26. Klein C, Grudzien M, Appaswamy G, et al. HAX1 deficiency

causes autosomal recessive severe congenital neutropenia

(Kostmann disease). Nat Genet 2007;39(1):86�92.

27. Beel K, Vandenberghe P. G-CSF receptor (CSF3R) mutations in

X-linked neutropenia evolving to acute myeloid leukemia or mye-

lodysplasia. Haematologica 2009;94(10):1449�52.

28. Donadieu J, Leblanc T, Bader Meunier B, et al. Analysis of risk

factors for myelodysplasias, leukemias and death from infection

among patients with congenital neutropenia. Experience of the

French Severe Chronic Neutropenia Study Group. Haematologica

2005;90(1):45�53.

29. Pinsk M, Burzynski J, Yhap M, Fraser RB, Cummings B, Ste-

Marie M. Acute myelogenous leukemia and glycogen storage dis-

ease 1b. J Pediatr Hematol Oncol 2002;24(9):756�8.

30. Link DC, Kunter G, Kasai Y, et al. Distinct patterns of mutations

occurring in de novo AML versus AML arising in the setting of

severe congenital neutropenia. Blood 2007;110(5):1648�55.

31. Connelly JA, Choi SW, Levine JE. Hematopoietic stem cell trans-

plantation for severe congenital neutropenia. Curr Opin Hematol

2012;19(1):44�51.

32. Choi SW, Levine J. Indications for hematopoietic cell transplanta-

tion for children with severe congenital neutropenia. Pediatr

Transplant 2010;14(8):937�9.

33. Kostmann R. Hereditar reticulos � en ny systemsjukdom. Svenska

Laekartidningen 1950;47:2861�8.

34. Kostmann R. Infantile genetic agranulocytosis; agranulocytosis

infantilis hereditaria. Acta Paediatr Suppl 1956;45(Suppl

105):1�78.

35. Klein C. Genetic defects in severe congenital neutropenia: emerg-

ing insights into life and death of human neutrophil granulocytes.

Annu Rev Immunol 2011;29:399�413.

36. Horwitz M, Benson KF, Person RE, Aprikyan AG, Dale DC.

Mutations in ELA2, encoding neutrophil elastase, define a 21-day

biological clock in cyclic haematopoiesis. Nat Genet 1999;23

(4):433�6.

37. Dale DC, Person RE, Bolyard AA, et al. Mutations in the gene

encoding neutrophil elastase in congenital and cyclic neutropenia.

Blood 2000;96(7):2317�22.

38. Bellanne-Chantelot C, Clauin S, Leblanc T, et al. Mutations in the

ELA2 gene correlate with more severe expression of neutropenia:

a study of 81 patients from the French Neutropenia Register. Blood

2004;103(11):4119�25.

39. Horwitz MS, Corey SJ, Grimes HL, Tidwell T. ELANE mutations

in cyclic and severe congenital neutropenia: genetics and patho-

physiology. Hematol Oncol Clin North Am 2013;27(1): 19�41. vii.

40. Xia J, Bolyard AA, Rodger E, et al. Prevalence of mutations in

ELANE, GFI1, HAX1, SBDS, WAS and G6PC3 in patients with

severe congenital neutropenia. Br J Haematol 2009;147

(4):535�42.

41. Zeidler C, Germeshausen M, Klein C, Welte K. Clinical implica-

tions of ELA2-, HAX1-, and G-CSF-receptor (CSF3R) mutations

in severe congenital neutropenia. Br J Haematol 2009;144

(4):459�67.

42. Horwitz MS, Duan Z, Korkmaz B, Lee HH, Mealiffe ME,

Salipante SJ. Neutrophil elastase in cyclic and severe congenital

neutropenia. Blood 2007;109(5):1817�24.

43. Germeshausen M, Deerberg S, Peter Y, Reimer C, Kratz CP,

Ballmaier M. The spectrum of ELANE mutations and their impli-

cations in severe congenital and cyclic neutropenia. Hum Mutat

2013;34(6):905�14.

44. Boxer LA, Stein S, Buckley D, Bolyard AA, Dale DC. Strong evi-

dence for autosomal dominant inheritance of severe congenital

neutropenia associated with ELA2 mutations. J Pediatr 2006;148

(5):633�6.

45. Ancliff PJ, Gale RE, Watts MJ, et al. Paternal mosaicism proves

the pathogenic nature of mutations in neutrophil elastase in severe

congenital neutropenia. Blood 2002;100(2):707�9.

46. Germeshausen M, Schulze H, Ballmaier M, Zeidler C, Welte K.

Mutations in the gene encoding neutrophil elastase (ELA2) are not

sufficient to cause the phenotype of congenital neutropenia. Br J

Haematol 2001;115(1):222�4.

47. Grenda DS, Murakami M, Ghatak J, et al. Mutations of the ELA2

gene found in patients with severe congenital neutropenia induce

the unfolded protein response and cellular apoptosis. Blood

2007;110(13):4179�87.

48. Kollner I, Sodeik B, Schreek S, et al. Mutations in neutrophil elas-

tase causing congenital neutropenia lead to cytoplasmic protein

accumulation and induction of the unfolded protein response.

Blood 2006;108(2):493�500.

49. Lane AA, Ley TJ. Neutrophil elastase cleaves PML-RARalpha and

is important for the development of acute promyelocytic leukemia

in mice. Cell 2003;115(3):305�18.

50. Boztug K, Rosenberg PS, Dorda M, et al. Extended spectrum of

human glucose-6-phosphatase catalytic subunit 3 deficiency: novel

genotypes and phenotypic variability in severe congenital neutrope-

nia. J Pediatr 2012;160(4): 679�83. e2.

51. McDermott DH, De Ravin SS, Jun HS, et al. Severe congenital

neutropenia resulting from G6PC3 deficiency with increased neu-

trophil CXCR4 expression and myelokathexis. Blood 2010;116

(15):2793�802.

616 PART | 2 Primary Immune Deficiencies

52. Banka S, Newman WG. A clinical and molecular review of ubiqui-

tous glucose-6-phosphatase deficiency caused by G6PC3 muta-

tions. Orphanet J Rare Dis 2013;8(1):84.

53. Smith C, Tenn C, Annett R. Some biochemical and behavioural

aspects of the paradoxical sleep window. Can J Psychol 1991;45

(2):115�24.

54. Hahn CN, Chong CE, Carmichael CL, et al. Heritable GATA2

mutations associated with familial myelodysplastic syndrome and

acute myeloid leukemia. Nat Genet 2011;43(10):1012�17.

55. Ostergaard P, Simpson MA, Connell FC, et al. Mutations in

GATA2 cause primary lymphedema associated with a predisposi-

tion to acute myeloid leukemia (Emberger syndrome). Nat Genet

2011;43(10):929�31.

56. Hsu AP, Sampaio EP, Khan J, et al. Mutations in GATA2 are asso-

ciated with the autosomal dominant and sporadic monocytopenia

and mycobacterial infection (MonoMAC) syndrome. Blood

2011;118(10):2653�5.

57. Emberger JM, Navarro M, Dejean M, Izarn P. Deaf-mutism,

lymphedema of the lower limbs and hematological abnormalities

(acute leukemia, cytopenia) with autosomal dominant transmission.

J Genet Hum 1979;27(3):237�45.

58. Pasquet M, Bellanne-Chantelot C, Tavitian S, et al. High frequency

of GATA2 mutations in patients with mild chronic neutropenia

evolving to MonoMAC syndrome, myelodysplasia, and acute mye-

loid leukemia. Blood 2013;121(5):822�9.

59. Gochuico BR, Huizing M, Golas GA, et al. Interstitial lung disease

and pulmonary fibrosis in Hermansky-Pudlak syndrome type 2, an

adaptor protein-3 complex disease. Mol Med 2012;18:56�64.

60. Dell’Angelica EC, Shotelersuk V, Aguilar RC, Gahl WA,

Bonifacino JS. Altered trafficking of lysosomal proteins in

Hermansky-Pudlak syndrome due to mutations in the beta 3 A sub-

unit of the AP-3 adaptor. Mol Cell 1999;3(1):11�21.

61. Jung J, Bohn G, Allroth A, et al. Identification of a homozygous

deletion in the AP3B1 gene causing Hermansky-Pudlak syndrome,

type 2. Blood 2006;108(1):362�9.

62. Jessen B, Bode SF, Ammann S, et al. The risk of hemophagocytic

lymphohistiocytosis in Hermansky-Pudlak syndrome type 2. Blood

2013;121(15):2943�51.

63. Bohn G, Allroth A, Brandes G, et al. A novel human primary

immunodeficiency syndrome caused by deficiency of the endoso-

mal adaptor protein p14. Nat Med 2007;13(1):38�45.

64. Bohn G, Hardtke-Wolenski M, Zeidler C, et al. Lethal graft-

versus-host disease in congenital neutropenia caused by p14 defi-

ciency after allogeneic bone marrow transplantation from an HLA-

identical sibling. Pediatr Blood Cancer 2008;51(3):436�8.

65. Kolehmainen J, Black GC, Saarinen A, et al. Cohen syndrome is

caused by mutations in a novel gene, COH1, encoding a transmem-

brane protein with a presumed role in vesicle-mediated sorting and

intracellular protein transport. Am J Hum Genet 2003;72

(6):1359�69.

66. Seifert W, Kuhnisch J, Maritzen T, Horn D, Haucke V, Hennies

HC. Cohen syndrome-associated protein, COH1, is a novel, giant

Golgi matrix protein required for Golgi integrity. J Biol Chem

2011;286(43):37665�75.

67. Kivitie-Kallio S, Norio R. Cohen syndrome: essential features, nat-

ural history, and heterogeneity. Am J Med Genet 2001;102

(2):125�35.

68. El Chehadeh S, Aral B, Gigot N, et al. Search for the best indica-

tors for the presence of a VPS13B gene mutation and confirmation

of diagnostic criteria in a series of 34 patients genotyped for sus-

pected Cohen syndrome. J Med Genet 2010;47(8):549�53.

69. Vilboux T, Lev A, Malicdan MC, et al. A congenital neutrophil

defect syndrome associated with mutations in VPS45. N Engl J

Med 2013;369(1):54�65.

70. Stepensky P, Saada A, Cowan M, et al. The Thr224Asn mutation

in the VPS45 gene is associated with congenital neutropenia and

primary myelofibrosis of infancy. Blood 2013;121:5078�87.

71. Strauss RG, Bove KE, Jones JF, Mauer AM, Fulginiti VA. An

anomaly of neutrophil morphology with impaired function. N Engl

J Med 1974;290(9):478�84.

72. Komiyama A, Morosawa H, Nakahata T, Miyagawa Y, Akabane

T. Abnormal neutrophil maturation in a neutrophil defect with

morphologic abnormality and impaired function. J Pediatr 1979;94

(1):19�25.

73. Breton-Gorius J, Mason DY, Buriot D, Vilde JL, Griscelli C.

Lactoferrin deficiency as a consequence of a lack of specific

granules in neutrophils from a patient with recurrent infections.

Detection by immunoperoxidase staining for lactoferrin and

cytochemical electron microscopy. Am J Pathol 1980;99

(2):413�28.

74. Parmley RT, Gilbert CS, Boxer LA. Abnormal peroxidase-positive

granules in “specific granule” deficiency. Blood 1989;73

(3):838�44.

75. Yamanaka R, Barlow C, Lekstrom-Himes J, et al. Impaired granu-

lopoiesis, myelodysplasia, and early lethality in CCAAT/enhancer

binding protein epsilon-deficient mice. Proc Natl Acad Sci USA

1997;94(24):13187�92.

76. Lekstrom-Himes JA, Dorman SE, Kopar P, Holland SM, Gallin JI.

Neutrophil-specific granule deficiency results from a novel muta-

tion with loss of function of the transcription factor CCAAT/

enhancer binding protein epsilon. J Exp Med 1999;189

(11):1847�52.

77. Kawai T, Malech HL. WHIM syndrome: congenital immune defi-

ciency disease. Curr Opin Hematol 2009;16(1):20�6.

78. Hernandez PA, Gorlin RJ, Lukens JN, et al. Mutations in the che-

mokine receptor gene CXCR4 are associated with WHIM syn-

drome, a combined immunodeficiency disease. Nat Genet 2003;34

(1):70�4.

79. McDermott DH, Liu Q, Ulrick J, et al. The CXCR4 antagonist

plerixafor corrects panleukopenia in patients with WHIM syn-

drome. Blood 2011;118(18):4957�62.

80. Dale DC, Bolyard AA, Kelley ML, et al. The CXCR4 antagonist

plerixafor is a potential therapy for myelokathexis, WHIM syn-

drome. Blood 2011;118(18):4963�6.

81. Person RE, Li FQ, Duan Z, et al. Mutations in proto-oncogene

GFI1 cause human neutropenia and target ELA2. Nat Genet

2003;34(3):308�12.

82. Armistead PM, Wieder E, Akande O, et al. Cyclic neutropenia

associated with T cell immunity to granulocyte proteases and a

double de novo mutation in GFI1, a transcriptional regulator of

ELANE. Br J Haematol 2010;150(6):716�19.

83. Ordonez-Rueda D, Jonsson F, Mancardi DA, et al. A hypomorphic

mutation in the Gfi1 transcriptional repressor results in a novel

form of neutropenia. Eur J Immunol 2012;42(9):2395�408.

617Chapter | 29 Congenital Neutropenia

84. Barth PG, Scholte HR, Berden JA, et al. An X-linked mitochon-

drial disease affecting cardiac muscle, skeletal muscle and neutro-

phil leucocytes. J Neurol Sci 1983;62(1�3):327�55.

85. Bione S, D’Adamo P, Maestrini E, Gedeon AK, Bolhuis PA,

Toniolo D. A novel X-linked gene, G4.5. is responsible for Barth

syndrome. Nat Genet 1996;12(4):385�9.

86. van Raam BJ, Kuijpers TW. Mitochondrial defects lie at the basis

of neutropenia in Barth syndrome. Curr Opin Hematol 2009;16

(1):14�19.

87. Rigaud C, Lebre AS, Touraine R, et al. Natural history of Barth

syndrome: a national cohort study of 22 patients. Orphanet J

Rare Dis 2013;8:70.

88. Shwachman H, Diamond LK, Oski FA, Khaw KT. The syndrome

of pancreatic insufficiency and bone marrow dysfunction. J

Pediatr 1964;65:645�63.

89. Bodian M, Sheldon W, Lightwood R. Congenital hypoplasia of

the exocrine pancreas. Acta Paediatr 1964;53:282�93.

90. Myers KC, Davies SM, Shimamura A. Clinical and molecular

pathophysiology of Shwachman-Diamond syndrome: an update.

Hematol Oncol Clin North Am 2013;27(1):117�28. ix.

91. Burwick N, Coats SA, Nakamura T, Shimamura A. Impaired ribo-

somal subunit association in Shwachman-Diamond syndrome.

Blood 2012;120(26):5143�52.

92. Donadieu J, Michel G, Merlin E, et al. Hematopoietic stem cell

transplantation for Shwachman-Diamond syndrome: experience

of the French neutropenia registry. Bone Marrow Transplant

2005;36(9):787�92.

93. Bhatla D, Davies SM, Shenoy S, et al. Reduced-intensity condi-

tioning is effective and safe for transplantation of patients with

Shwachman-Diamond syndrome. Bone Marrow Transplant

2008;42(3):159�65.

94. Erickson RP. Southwestern Athabaskan (Navajo and Apache)

genetic diseases. Genet Med 1999;1(4):151�7.

95. Walne AJ, Vulliamy T, Beswick R, Kirwan M, Dokal I.

Mutations in C16orf57 and normal-length telomeres unify a

subset of patients with dyskeratosis congenita, poikiloderma with

neutropenia and Rothmund-Thomson syndrome. Hum Mol Genet

2010;19(22):4453�61.

96. Volpi L, Roversi G, Colombo EA, et al. Targeted next-generation

sequencing appoints c16orf57 as clericuzio-type poikiloderma

with neutropenia gene. Am J Hum Genet 2010;86(1):72�6.

97. Shchepachev V, Wischnewski H, Missiaglia E, Soneson C,

Azzalin CM. Mpn1, mutated in poikiloderma with neutropenia

protein 1, is a conserved 30-to-50 RNA exonuclease processing U6

small nuclear RNA. Cell Rep 2012;2(4):855�65.

98. Hilcenko C, Simpson PJ, Finch AJ, et al. Aberrant 30 oligoadeny-lation of spliceosomal U6 small nuclear RNA in poikiloderma

with neutropenia. Blood 2013;121(6):1028�38.

99. Mroczek S, Krwawicz J, Kutner J, et al. C16orf57, a gene

mutated in poikiloderma with neutropenia, encodes a putative

phosphodiesterase responsible for the U6 snRNA 30 end modifica-

tion. Genes Dev 2012;26(17):1911�25.

100. Nalls MA, Wilson JG, Patterson NJ, et al. Admixture mapping of

white cell count: genetic locus responsible for lower white blood

cell count in the Health ABC and Jackson Heart studies. Am J

Hum Genet 2008;82(1):81�7.

101. Reich D, Nalls MA, Kao WH, et al. Reduced neutrophil count in

people of African descent is due to a regulatory variant in the

Duffy antigen receptor for chemokines gene. PLoS Genet 2009;5

(1):e1000360.

102. Horuk R, Chitnis CE, Darbonne WC, et al. A receptor for the

malarial parasite Plasmodium vivax: the erythrocyte chemokine

receptor. Science 1993;261(5125):1182�4.

103. Lee JS, Frevert CW, Wurfel MM, et al. Duffy antigen facilitates

movement of chemokine across the endothelium in vitro and pro-

motes neutrophil transmigration in vitro and in vivo. J Immunol

2003;170(10):5244�51.

104. Lee JS, Wurfel MM, Matute-Bello G, et al. The Duffy antigen

modifies systemic and local tissue chemokine responses following

lipopolysaccharide stimulation. J Immunol 2006;177(11):8086�94.

618 PART | 2 Primary Immune Deficiencies