IN UTERO EXPOSURE TO VALPROATE INCREASES THE RISK FOR ISOLATED CLEFT PALATEAdam Jackson1, Rebecca Bromley2, James Morrow3, Beth Irwin3, Jill Clayton-Smith4

1Blackpool Victoria Hospital, Whinney Heys Road, Blackpool, Lancashire, United Kingdom, FY3 8NR

2The University of Manchester, Institute of Human Development, United Kingdom, M13 9PL

3Neurology Department, Belfast Health and Social Care Trust, Royal Victoria Hospital, Belfast, Co Antrim,

Northern Ireland, BT12 6BA

4Manchester Centre For Genomic Medicine, Central Manchester University Hospitals, Manchester, United

Kingdom, M13 9WL

Correspondence to:

Adam Jackson

Postal address: Blackpool Victoria Hospital, Whinney Heys Road, Blackpool, UK, FY3 8NR

Email: Adam.jackson@doctors.org.uk

Telephone: 07976056436

Keywords:

Valproate, orofacial, clefting, palate, pregnancy

Word Count (excluding title page, abstract, references, figures and tables): 2925

ABSTRACT:

INTRODUCTION: Orofacial clefting (OFC) has been described in infants exposed to sodium

valproate (VPA) prenatally, but often no distinction is made between cleft lip and palate

(CLP), and cleft palate only (CPO). This distinction is important as these conditions have

different management implications and the distinction has implications too for

understanding the teratogenic mechanisms .

METHODS: Using the Pubmed database, case reports and observational studies describing

OFC in association with VPA exposure were identified. Searches for similarly exposed

patients referred to a regional genetic centre and those recorded in the UK Epilepsy and

Pregnancy Register (UKEPR) were undertaken. Cleft type and, where available, VPA doses

prescribed were recorded.

RESULTS: Twelve out of fifteen published cases had CPO and five out of ten observational

studies showed an increase in CPO compared to CLP. Eight patients ascertained through the

regional genetic centre had CPO. Thirteen cases of OFC occurred in 1282 VPA monotherapy

exposed pregnancies on the UKEPR; nine had CPO and four had CLP, representing an 11.3-

fold and 3.5-fold increase risk in CPO and CLP, respectively over general population risk.

Doses ranged from 200-2500mg VPA daily with 73% of monotherapy CPO cases from the

local cohort and UKEPR occurring at doses over 1000mg.

CONCLUSIONS: CPO is the predominant cleft-type seen in prenatal VPA exposure. Parents

should be counselled appropriately and infants should undergo review after delivery for

CPO. Pregnancy registers collecting information on congenital anomalies should make the

distinction between CLP and CPO as the risk differs across the two conditions.

INTRODUCTION

Foetal Valproate Syndrome (FVS) describes a constellation of features that has been

recognised in a number of children exposed to valproic acid (VPA) in utero. First delineated

in 1984 by DiLiberti et al.1, FVS is characterised by a pattern of major and minor

malformations and neurodevelopmental problems together with a distinctive facial

phenotype. The latter includes medial deficiency of the eyebrows which tend to be neat and

arched, a prominent infra-orbital groove, a broad and flat nasal bridge, a smooth philtrum

with a thin vermillion border to the upper lip and a small, downturned mouth with an

everted lower lip. Congenital abnormalities which occur at greater frequency in FVS include

neural tube defects, radial ray defects, trigonocephaly and heart defects. A dose dependent

effect of VPA has been established,2 with doses above 1000mg daily being associated with a

greater risk of congenital malformations. The risk of cognitive impairment is increased with

increasing dose.3

Orofacial clefting (OFC) has been associated with exposure to VPA in utero4 and has been

described as a feature of FVS.5 However, the spectrum of OFC includes both cleft lip and/or

palate (CLP) and cleft palate only (CPO). The causes and developmental pathogeneses of

these two conditions are different as are the management interventions required and

outcomes expected after surgical correction. Children who have CLP are managed on a

different care pathway from those who have CPO. The number and types of surgical

interventions will differ, for example, and children with an isolated cleft lip are not likely to

need the same speech and language interventions or to have the middle ear complications

that are so frequent in patients with cleft palate. The implications for the two conditions are

thus different and to provide correct information to parents about cause, management,

complications and prognosis it is important to make the distinction between CLP and CPO.

In the case of FVS, many patient information leaflets, websites, published papers and

textbooks link VPA exposure in pregnancy with an increased incidence of OFC but do not go

into details as to whether this association is more likely to be with CLP or CPO.6,7,8

From a teratological point of view it is also important to distinguish between the two types

of OFC as there are different causal mechanisms9. Further, current practice in most

malformation registries is to report a single incidence figure for OFC, combining both CLP

and CPO; however if there are mechanistic differences the risks associated with each time of

OFC may differ and combining them may lead to unreliable risk estimates.

In the 4th week of gestation, the first pair of pharyngeal arches gives rises to paired maxillary

and mandibular prominences which approximate a single frontonasal prominence. In the

next two weeks, the maxillary prominences grow medially and fuse with the medial nasal

prominences forming the philtrum, upper jaw and the triangular primary palate. In the sixth

week of development, the palatine shelves which are outgrowths of the maxillary

prominences progress obliquely downward on each side of the tongue. It is in the seventh

week that these shelves turn horizontally and fuse creating the secondary palate with the

incisive foramen marking the division of the secondary and primary palates.10

Clefts anterior to the incisive foramen cause CLP, arising from incomplete fusion of the

maxillary prominence with the medial nasal prominence. Clefts posterior to the incisive

foramen cause CPO, arising from incomplete fusion of the palatine shelves. CPO can lead to

velopharyngeal insufficiency and carries significant risk of chronic otitis media, hearing loss

and abnormal speech, unlike CLP.11

Antenatal ultrasound scans (USS) are helpful for identifying congenital malformations and

allow both parents and clinicians to make preparations for the management of these

conditions after birth. In the UK every pregnant mother is offered a detailed fetal anomaly

scan at around 20 weeks of pregnancy. Offerdal et al. (2008) studied 49 314 pregnancies in

Norway and found a pickup rate of 43% (35 out of 77 cases) for CLP and 0% (0 out of 24

cases) for CPO.12 A novel 3D sonographic technique proposed by Campbell et al. allowed for

improved antenatal detection for CPO.13 Overall, however, in a routine ante-natal setting a

scan which is negative for CLP does not exclude CPO.

Martinez-Frias et al. 199014 stated that OFC only occurred in children exposed to VPA in

utero as polytherapy. However, two large epidemiological studies (Jentink et al. 2010,

Gilboa et al. 2011) have since found an increased odds ratio for CPO for children of mothers

taking VPA monotherapy. The authors’ anecdotal experience of children exposed to VPA in

utero who have attended both a cleft clinic and the regional genetic clinic in Manchester,

together with the results of cohort studies of children exposed to antiepileptic drugs in

utero carried out within the North West of England have suggested that CLP is, in fact,

unusual after VPA exposure in utero and that CPO is in fact much more likely. Such

observations led to this review of the available literature and of other known patients with

OFC following VPA exposure.

METHODS

A literature search was undertaken to identify any case reports, case series or cohort studies

that described OFC occurring in association with FVS. Searches were conducted in PubMed,

from conception to March 2014 with no language restrictions using the search terms ‘fetal

valproate syndrome’, ‘valproate cleft lip’, ‘valproate cleft palate’ and ‘anti-epileptic drugs

pregnancy cleft lip palate’. Studies were filtered to include only those that described OFC

occurring in VPA exposed patients, whether available in abstract or full-text form. A manual

literature search was also undertaken to identify any additional reports and meeting

abstracts in the investigators’ personal collections. All reports were reviewed and, where

possible, information on VPA dosage during gestation was recorded. Finally, additional cases

known to the authors through attendance at a regional genetic clinic were reviewed .

Finally, data was obtained from the UK Epilepsy and Pregnancy Register about cases with a

history of VPA exposure and OFC. All patient data was anonymised for analysis but cleft

status remained linked to AED type and dose.

RESULTS

Cases reported in the literature

Report No affected individuals / total reported

Doses Type of OFC

Yaqoob et al.15 1/1 - CPOSchorry et al.16 1/5 750mg VPA CPOOzkinay et al.17 1/1 1800mg VPA

100mg LTGCPO(XXX karyotype)

Zaki et al.18 1/1 1200mg VPA CPOBoyle et al.19 1/1 2300mg VPA CPOEpinasse et al.20 1/4 - ‘Oral

clefting’Okada et al.21 1/1 - CPOWinter et al.22 1/4 1500mg VPA

600mg CBZCPO

Halder et al.23 1/1 900mg VPA CPOMalm et al.24 2/7 2500mg VPA CPO

2500mg VPA CPOLindhout et al.25 2/18 (cohorts

A and B)600mg VPA, 800mg CBZ,

CL

150mg PHB, 300mg PHT900mg VPA, 600mg CBZ, 150mg PHB, 300mg PHT

CLP

Eroglu et al.26 1/2 1000mg VPA CPOJackson et al.27 1/4 1500mg VPA CPO

Table 1: Case reports describing OFC in FVS. VPA, sodium valproate. LTG,

lamotrigine. CBZ, carbemazepine. PHB, phenobarbitone. PHT, phenytoin.

32 publications describing children exposed to VPA in pregnancy were identified, describing

116 children. Thirteen papers reported the occurrence of OFC with 15 affected individuals

(Table 1): 12 had CPO, one CL, one CLP and one reported as ‘oral clefting’ with no further

information. Doses during pregnancy were available for 12/15 individuals, ranging from

600mg to 2500mg daily (mean = 1454mg daily). Polytherapy had been used in 4/12 cases

(with lamotrigine, carbamazepine, phenobarbitone and phenytoin)

For those where drug dose was reported, 8/10 (80%) of CPO cases occurred in patients

exposed to over 1000mg VPA in utero, whereas 2/2 (100%) of CLP cases occurred in patients

exposed to less than 1000mg in utero. One of the affected CPO patients was reported to

have a XXX karyotype, a condition which is not known to be associated specifically with CPO.

Study Reference

Population OFC CPO CLP

Jentink et al.28 – meta-analysis

1565 VPA monotherapy

13 13 0

Jentink et al. –EUROCAT case-control

2244 VPA monotherapy

13 13 (Odds Ratio, OR 5.2)

0

studyGilboa et al.29 – meta-analysis

Meta-analysis of articles quoting association of VPA with birth defects11 included

- OR 5.8 Not stated

Vajda et al.30 447 VPA exposed (mono or polytherapy)

5 No distinction

No distinction

Endo et al.31 25 VPA polytherapy

1 0 1*

Moore et al.32 34 VPA monotherapy

0 0 0

Kozma et al.33 – meta-analysis**

70 VPA monotherapy

3 3 0

Samren et al.34

184 VPA monotherapy

0 0 0

118 VPA polytherapy

1 No distinction

No distinction

Hernandez-Diaz et al.4 ***

323 VPA monotherapy

3 2 1

NOTE:

*In this case, the mother was taking 1400mg VPA, 1.5mg clonazepam and 200mg zonisamide daily.

**2 of these cases (Winter et al and Okada et al.) were reported above as case reports

*** Found in the supplementary outcome data

Table 2: Observational studies and Systematic Reviews describing OFC in FVS.

Seven observational studies and three literature reviews were identified using the search

strategy described (Table 2). Jentink et al. (2010) reviewed the literature on malformations

in FVS and included eight studies in a meta-analysis of 1565 patients. Three of these eight

studies were also identified by the search strategy but have only been included as a

composite of Jentink et al. The 14 most common malformations found in this meta-analysis

were then assessed for association with VPA monotherapy exposure in the first trimester by

a case-control study using the European Surveillance of Congenital Abnormalities

(EUROCAT) database. This study found CPO to be significantly associated with VPA

exposure in the meta-analysis and found that this association remained in the case-control

study. Gilboa et al.( 2011) undertook another meta-analysis which found an increased odds

ratio for CPO in VPA exposure.

Cleft-type was not distinguished by Vajda et al. (2013) or Samren et al. (1997). CPO was

identified in 3/70 patients by Kozma et al. (2001) (general population risk 1 in 700, although

there is regional variation35) and in 2/323 by Hernandez-Diaz et al. (2012). One case of CLP

was noted by both Hernadez-Diaz et al (2012) and Endo et al. (2004). Moore et al. (2000)

reported no patients with CLP or CPO when reviewing 34 cases of VPA exposure.

Few observational studies reported the dose taken by mothers during pregnancy. Only

Endo et al. (2004) provided this information and in this case there was one CLP in a

pregnancy exposed to 1400mg VPA daily.

In summary, 54 children with clefting following VPA exposure were identified from

published cases with 43 of these cases being CPO.

Cases ascertained through the Regional Genetic Service

The case notes of all individuals known to the Regional Genetic Service in Manchester, who

had been exposed to VPA in pregnancy and who had been noted to have a clefting disorder

were reviewed. A summary of these cases is presented in Table 3. All of the eight cases had

CPO and no cases were found reporting CLP. The dose of VPA taken during pregnancy

ranged from 1200mg to 2000mg daily (mean = 1533mg). One of these cases had been

included in the study by Meador et al. (2006)5 and was not, therefore, a new case.

Patient Sex Type of cleft Dose of VPA

1 F CPO 1200mg*

2 M CPO 1800mg*

3 M CPO 1500mg**

4 F CPO Unknown

5 F CPO 1200mg

6 F Submucous CPO

2000mg

7 M Bifid uvula 1500mg

8 F CPO Unknown

NOTE:

* These cases were referred to in a review of FVS by Clayton-Smith and Donnai (1995)36

** Patient 3 as reported by Jackson et al. (2014)26

Table 3: Case of FVS and OFC known to Manchester Regional Genetic Service.

Cases ascertained through the UK Epilepsy and Pregnancy register

The UK Epilepsy and Pregnancy Register (UKEPR) was set up in 1996 with the aim of

establishing the risks conferred by intra-uterine exposure to single anti-epileptic drugs

(AEDs) during pregnancy for major congenital malformations (MCM). The most recent

update was published in February 2014 by Campbell et al.37 and found the MCM rate to be

highest (6.7%) for VPA monotherapy exposure in utero. This is in comparison to 2.6% and

2.3% for carbamazepine and lamotrigine, respectively. Campbell et al. described 13 cases of

OFC occurring in 1282 VPA monotherapy exposed pregnancies; however, no distinction was

made between CLP and CPO in that report. Through personal correspondence and the

contribution of co-authors JM and BI, further details of the cleft phenotypes from these

patients are presented in Table 4, along with an additional four cases of OFC from the

register where VPA was used as polytherapy.

Outcomes OFC CPO CLPCL CLP

Monotherapy 1282 13 9 1 3Polytherapy 527 4 4 0 0

Table 4: Summary statistics from the UKEPR on OFC and exposure to VPA

Case Daily Dose VPA Cleft type Other features

Monotherapy

1 400mg CPO (Bilateral) Micrognathia

2 600mg CLP -

3 1200mg CPO Micrognathia

4 1600mg CPO -

5 2000mg CLP Dysmorphism‘Hyperketonism’

6 200mg CPO -

7 800mg CLP -

8 1500mg CPO -

9 800mg CPO Congenital hypotonia

10 1500mg (conception)1000mg (pregnancy)

CPO -

11 900mg CPO ASD

12 2500mg CPO Motor delayHip problem

13 800mg CL (involving gum) -

Polytherapy

1 2000mg VPA1800mg Gabapentin(CBZ stopped around conception)

CPO (Bilateral) Absent palmar creases

2 400mg VPA1000mg CBA

CPO Intracerebral haemorrhageDelivered at 31 weeks

3 500mg VPA500mg Topiramate

CPO Fetal valproate syndromeCrossed toes

4 1500mg VPA1.5mg Clonazepam

CPO -

Table 5: Breakdown of OFC cases exposed to VPA in either monotherapy or

polytherapy from the UKEPR.

Effect of dose of VPA on cleft occurrence and type

Of the patients identified from the local cohort and those seen in the UKEPR where the dose

was known, 11/15 (73%) of CPO monotherapy cases occurred in children exposed to over

1000mg VPA daily. If the 4 polytherapy cases are included, 13/19 (68%) occurred in

pregnancies exposed to over 1000mg daily. This is in contrast to CLP where 75% of cases

were exposed to less than 1000mg daily.

DISCUSSION

This review has demonstrated that based on the published literature and on cases known to

the authors the increased prevalence of clefting in children exposed to VPA is not due to an

increase in both CLP and CPO or to CLP alone but just to an increase in CPO . This pattern

was found to hold true across both monotherapy and polytherapy exposures. The

International Perinatal Database of Typical Oral Clefts (IPTOC)38 and EUROCAT working

groups39 found the prevalence of CL, CLP and CPO in the European population to be 3.28,

6.64 and 6.20 per 10 000. Based on the UK pregnancy and epilepsy register, the prevalence

of CL, CLP and CPO in VPA monotherapy exposure is 7.80, 23.40 and 70.20 per 10 000 live

births respectively. This represents an 11.3-fold increase in CPO, 3.5-fold increase in CLP and

a 2.4-fold increase in CL.

Many studies and reports have until now, described OFC as a single entity when discussing

risks of prenatal VPA exposure, resulting in patient information leaflets which suggest that

FVS patients are at risk of CLP as well as CPO. To some extent this may be true but the risk

for CPO is much greater, and CPO is associated with many more complications which require

ongoing management such as velopharyngeal insufficiency and hearing loss. Antenatal

ultrasound scans have a much higher pickup rate for CLP than CPO as isolated palatal clefts

are rarely detected. Newer diagnostic techniques, such as 3D USS, may increase the pickup

rate of CPO and could, therefore, be beneficial to expectant mothers who are taking VPA.

Making clinicians aware that CPO is a much more common outcome than CLP in VPA

exposed babies allows for appropriate prenatal counselling for parents.

There also appears to be a dose-dependent relationship as the risks of CPO for the offspring

of women taking over 1000mg daily are much greater than those who are taking less than

1000mg. Observation of a dose-dependent effect is one of the hallmarks of teratogenicity40.

In our study we observed a dose-dependent effect for CPO but not for CLP. Studies and

pregnancy registers recording outcomes after exposure to VPA in utero should be

encouraged to distinguish between CLP and CPO to study these effects further and to allow

for more precise risk estimates to be communicated to both prescribers and women for

whom VPA is a treatment option.

VPA is a broad class I and II histone deacetylase (HDAC) inhibitor, which brings about

changes in gene expression.41 It has been shown to bring about a state of hypervitaminosis

A by reducing expression of retionic acid binding protein (RBP4).42 Lammer et al. (1985)

described 21 infants who had been exposed to isoretinoin (a vitamin A analogue and acne

treatment) in utero, three of which had CPO.43 Vitamin A has also been implicated in the

prevention of cleft palate in a 2008 Norwegian case-control study, which found that higher

maternal vitamin A intake reduced the risk of CPO but not CL or CLP.44 However, they used

a questionnaire-based study and maternal multivitamin and dietary intake as surrogate

markers for vitamin A consumption. It is likely that the doses used in treating skin

conditions are much higher. The concentration of retinoic acid appears to be important in

palatogenesis and future research will help to understand the teratogenic action of VPA in

relation to CPO

CONCLUSION

The published literature, our own clinical observations and evidence from the UKEPR appear

to agree that exposure to VPA in utero increases the risk of CPO and this applies to both

monotherapy and polytherapy. Further research is needed to identify a causative

mechanism in VPA-induced CPO.

Competing Interests Dr Morrow is the lead for the UK Epilepsy and Pregnancy Register. The

UK Epilepsy and Pregnancy Register has received a research grants from the Epilepsy

Research Foundation and a number of educational grants from pharmaceutical companies

(Parke Davis, Glaxo Smith Kline, Eisai, Novartis, Sanofi-Aventis, Pfizer, Janssen-Cilag and

UCB). Dr Bromley and Professor Clayton Smith have worked in the past on studies funded by

Sanofi Aventis and UCB Pharma. The funders had no role in performing this research or

preparing the manuscript.

Funding and all other required statements: No direct funding was provided for this study

however Dr Bromley is currently supported by National Institute for Health Research (PDF-

2013-06-041). Cleft research within the University of Manchester is supported by the Healing

Foundation UK Cleft Cooperative.

Ethical Approval: Ethical approval was not sought specifically for this study as it did not

involve direct interventions for human subjects and all clinical data was anonymised.

Patients recruited previously to the UK Pregnancy and Epilepsy Register and to the North

West England Cohort Studies have consented to use of their data.

What is already known on this topic:

Orofacial clefting, which includes cleft lip and palate and cleft palate only, occurs more

commonly in children exposed to valproate in utero. Previous studies have not assessed

which cleft-type is most common in this population.

What this study adds:

This study confirms that OFC is associated with both mono- and polytherapy valproate

exposure during pregnancy and demonstrates that CPO is the predominant cleft-type. This

enables appropriate parental counselling with regards to medical complications which may

be present and implications for long term management of their child after birth. CPO being

more prevalent than CLP highlights the need for condition specific teratologenic risk

estimates to be generated for these two distinct conditions.

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