Mitochondrial Autism—Mitochondrial Autism—A Unique A Unique Subpopulation and Subpopulation and Piece of the Puzzle?Piece of the Puzzle?

Presented 5/25/2008Presented 5/25/2008By Jon S. Poling MD PhDBy Jon S. Poling MD PhDClinical Assistant Professor, Clinical Assistant Professor, Department of Neurology, Medical Department of Neurology, Medical College of GeorgiaCollege of GeorgiaPartner, Athens Neurological Partner, Athens Neurological AssociatesAssociates

““The Low Hanging Fruit” The Low Hanging Fruit” for Diagnosis and for Diagnosis and TreatmentTreatment1.1. Mitochondrial Mitochondrial

DysfunctionDysfunction

2.2. Immune Immune dysfunction/ dysfunction/ inflammatory inflammatory biomarkersbiomarkers

Guiding Principles Guiding Principles of New Paradigmof New Paradigm

Autism is a behavioral syndrome, not a medical Autism is a behavioral syndrome, not a medical diagnosis, with multiple etiologies.diagnosis, with multiple etiologies.

The prevalence of Autism is increasing—which The prevalence of Autism is increasing—which autism(s)?autism(s)?

The rise in Autism cases is due to a complex The rise in Autism cases is due to a complex interaction between genetics and environment.interaction between genetics and environment.

Autism is a systemic disorder with primary Autism is a systemic disorder with primary neurological manifestations.neurological manifestations.

Based on biological markers, subpopulations must Based on biological markers, subpopulations must be distinguished to guide proper basic science, be distinguished to guide proper basic science, epidemiology, diagnosis, treatment, and prevention.epidemiology, diagnosis, treatment, and prevention.

Epidemiology and Genetics have to date failed Epidemiology and Genetics have to date failed Autism because the clinicians have not properly Autism because the clinicians have not properly defined the endophenotypes/subpopulations defined the endophenotypes/subpopulations

The Mighty The Mighty MitochondriaMitochondria

1000 proteins located in the mitochondria, 13 are encoded by the mitochondrial DNA (mtDNA), while 1000 proteins located in the mitochondria, 13 are encoded by the mitochondrial DNA (mtDNA), while the remainder are nuclear-encoded (on the chromosomes) and imported into mitochondria.the remainder are nuclear-encoded (on the chromosomes) and imported into mitochondria.

75% sporadic occurence 75% sporadic occurence

Mitochondrial diseaseMitochondrial disease

Young field, 1988 DC Wallace, Young field, 1988 DC Wallace, Leber’sLeber’s

Extremely complex genetics and Extremely complex genetics and clinical phenotypesclinical phenotypes

mtDNA and nuclear DNAmtDNA and nuclear DNA Not just powerhouse—Not just powerhouse—

programmed (apoptotic) cell programmed (apoptotic) cell deathdeath

Genotypes known now to have Genotypes known now to have multiple phenotypesmultiple phenotypes

http://neuromuscular.wustl.edu/pathol/diagrams/mito.htmhttp://www.umdf.org/http://www.clevelandclinic.org/health/health-info/docs/1600/1678.asp?index=6957

Autism Autism &&

Mitochondrial Mitochondrial DysfunctionDysfunction

A New Medical Finding?A New Medical Finding?

New Or Redux?New Or Redux?

Dr. Mary Coleman, Dr. Mary Coleman, Georgetown U 1985Georgetown U 1985

1.1. 4 of 80 (5%) of patients 4 of 80 (5%) of patients with lactic acidemiawith lactic acidemia

2.2. 1 of 4 pts with regression1 of 4 pts with regression

3.3. Propose primary defect in Propose primary defect in carbohydrate carbohydrate metabolism, pyruvate metabolism, pyruvate dehydrogenase dehydrogenase

4.4. Speculate that Ketogenic Speculate that Ketogenic diet may be helpfuldiet may be helpful

Autism Autism &&

Mitochondrial Mitochondrial DysfunctionDysfunction

A rare and A rare and unique situation?unique situation?

Mitochondrial Dysfunction emerging as Mitochondrial Dysfunction emerging as most common medical condition most common medical condition associated with autism.associated with autism. Of 159 autism patients in one autism clinic, 38% Of 159 autism patients in one autism clinic, 38%

had non-specific biochemical abnormalities. had non-specific biochemical abnormalities. Poling Poling et al. Developmental regression and mitochondrial et al. Developmental regression and mitochondrial dysfunction in a child with autism.dysfunction in a child with autism. J Child Neurol, J Child Neurol, 2006. 2006. 2121(2): p. 170-2.(2): p. 170-2.

7.2% of patients with Autism could be classified as 7.2% of patients with Autism could be classified as having a ‘definite’ mitochondrial respiratory chain having a ‘definite’ mitochondrial respiratory chain disorder and 20% had elevated serum lactic acid disorder and 20% had elevated serum lactic acid Oliveira, G., et al., Oliveira, G., et al., Mitochondrial dysfunction in Mitochondrial dysfunction in autism spectrum disorders: a population-based autism spectrum disorders: a population-based study.study. Dev Med Child Neurol, 2005. Dev Med Child Neurol, 2005. 4747(3): p. 185-(3): p. 185-9.9.

22ndnd study 4%; Oliveira, G., et al., study 4%; Oliveira, G., et al., Epidemiology of Epidemiology of autism spectrum disorder in Portugal: prevalence, autism spectrum disorder in Portugal: prevalence, clinical characterization, and medical conditions.clinical characterization, and medical conditions. Dev Med Child Neurol, 2007. Dev Med Child Neurol, 2007. 4949(10): p. 726-33. (10): p. 726-33.

Mitochondrial Dysfunction emerging as Mitochondrial Dysfunction emerging as most common medical condition most common medical condition associated with autism.associated with autism.

36% of 100 autism patients have total carnitine 36% of 100 autism patients have total carnitine levels 1SD below mean control, pattern suggestive levels 1SD below mean control, pattern suggestive mild mitochondrial dysfunction. Filipek, P.A., et al., mild mitochondrial dysfunction. Filipek, P.A., et al., Relative carnitine deficiency in autism.Relative carnitine deficiency in autism. J Autism J Autism Dev Disord, 2004. Dev Disord, 2004. 3434(6): p. 615-23. (6): p. 615-23.

65% of autism pts referred for mitochondrial 65% of autism pts referred for mitochondrial evaluation to specialty clinic positive for OxPhos evaluation to specialty clinic positive for OxPhos disorder on muscle biopsy. Shoffner, J., L.C. disorder on muscle biopsy. Shoffner, J., L.C. Hyams, and G.N. Langley, Hyams, and G.N. Langley, Oxidative Oxidative Phosphorylation (OXPHOS) Defects in Children Phosphorylation (OXPHOS) Defects in Children with Autistic Spectrum Disorderswith Autistic Spectrum Disorders, in , in AANAAN. 2008: . 2008: Chicago. Chicago.

0

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0 10 20 30

Years

AS

T (

IU/L

)Autistic Spectrum Cases--AST vs. Age

AST declines by 3.2 IU/L/10years

JS Poling Johns Hopkins Neurology Grand Rounds 6/21/2001Metabolic Disturbances in Autistic Children: The KKI Experience from 1995-2001

0

50

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0 5 10 15 20

CK

Autistic Spectrum--CPK

Mean 168N=14

7 of 14 elevated 50%

IU/L

Age (years)

JS Poling Johns Hopkins Neurology Grand Rounds 6/21/2001Metabolic Disturbances in Autistic Children: The KKI Experience from 1995-2001

0

1

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5

0 5 10 15 20

Lactate

6 of 15 elevated

Autistic Spectrum—Lactate

(40%)

Age (years)

Mm

ol/

L

In the prelim evaluation of Dr. Kelley’s data 12/36 (25%) of autistic children have elevated alanine/lysine

MitochondriaMitochondria

Corner Piece Corner Piece of the of the Puzzle??Puzzle??

Can Autism Be A Can Autism Be A Mitochondrial Disease? Mitochondrial Disease? Clinical Convergent Clinical Convergent Evidence 1Evidence 1

3+ systems involved, fluctuating 3+ systems involved, fluctuating symptoms, intolerance to symptoms, intolerance to fasting/dietary changesfasting/dietary changes

Nervous system, muscle, gut, Nervous system, muscle, gut, immune system involvement—most immune system involvement—most energy dependent tissuesenergy dependent tissues

Response to carbohydrate exclusive Response to carbohydrate exclusive diets (GCFC, ketogenic, specific diets (GCFC, ketogenic, specific carbohydrate)carbohydrate)

High heritability by family history with High heritability by family history with near failure of classic Mendelian near failure of classic Mendelian genetics to explaingenetics to explain

Spectrum of severitySpectrum of severity

Can Autism Be A Can Autism Be A Mitochondrial Disease? Mitochondrial Disease? Biochemical Convergent Biochemical Convergent Evidence 2Evidence 2

Proposed environmental precipitants may Proposed environmental precipitants may selectively injury metabolically susceptible selectively injury metabolically susceptible individuals.individuals.

Data analogous to Parkinson’s disease Data analogous to Parkinson’s disease research.research.

Environmental/Epigenetic toxins act via Environmental/Epigenetic toxins act via mitochondrial mechanism mitochondrial mechanism

Other non-mitochondrial genetic lesions which Other non-mitochondrial genetic lesions which increase oxidative stress increase ASD riskincrease oxidative stress increase ASD risk

1.1. GSTP1*A haplotype Williams, T.A., et al., GSTP1*A haplotype Williams, T.A., et al., Risk of autistic Risk of autistic disorder in affected offspring of mothers with a disorder in affected offspring of mothers with a glutathione S-transferase P1 haplotype.glutathione S-transferase P1 haplotype. Arch Pediatr Arch Pediatr Adolesc Med, 2007. Adolesc Med, 2007. 161161(4): p. 356-61. (4): p. 356-61.

2.2. James, S.J., et al., James, S.J., et al., Metabolic endophenotype and Metabolic endophenotype and related genotypes are associated with oxidative stress related genotypes are associated with oxidative stress in children with autism.in children with autism. Am J Med Genet B Am J Med Genet B Neuropsychiatr Genet, 2006. Neuropsychiatr Genet, 2006. 141141(8): p. 947-56.(8): p. 947-56.

Can Autism Be A Mitochondrial Can Autism Be A Mitochondrial Disease? Divergent Evidence Disease? Divergent Evidence

Multiple Multiple mitochondrial mitochondrial lesions appear lesions appear to produce an to produce an ASD phenotype ASD phenotype

Divergent EvidenceDivergent Evidence

1.1. 15q inverted duplication15q inverted duplication Filipek, P.A., et al., Filipek, P.A., et al., Mitochondrial dysfunction in autistic patients with Mitochondrial dysfunction in autistic patients with 15q inverted duplication.15q inverted duplication. Ann Neurol, 2003. Ann Neurol, 2003. 5353(6): (6): p. 801-4. PRADER WILLI TYPE MUTATIONp. 801-4. PRADER WILLI TYPE MUTATION

2.2. A3243G mtDNA mutation and mtDNA A3243G mtDNA mutation and mtDNA depletion.depletion. Pons, R., et al., Pons, R., et al., Mitochondrial DNA Mitochondrial DNA abnormalities and autistic spectrum disorders.abnormalities and autistic spectrum disorders. J J Pediatr, 2004. Pediatr, 2004. 144144(1): p. 81-5. MIDD MELAS (1): p. 81-5. MIDD MELAS MUTATIONMUTATION

3.3. mitochondrial DNA G8363A transfer RNA(Lys) mitochondrial DNA G8363A transfer RNA(Lys) mutation.mutation. Graf, W.D., et al., Graf, W.D., et al., Autism associated Autism associated with the mitochondrial DNA G8363A transfer with the mitochondrial DNA G8363A transfer RNA(Lys) mutation.RNA(Lys) mutation. J Child Neurol, 2000. J Child Neurol, 2000. 1515(6): p. (6): p. 357-61. MERRF, LEIGH, CARDIOMYOPATHY, ATAXIA 357-61. MERRF, LEIGH, CARDIOMYOPATHY, ATAXIA LIPOMA SYNDROMELIPOMA SYNDROME

4.4. Rett Syndrome MECP2 knockout.Rett Syndrome MECP2 knockout. Kriaucionis, Kriaucionis, S., et al., S., et al., Gene expression analysis exposes Gene expression analysis exposes mitochondrial abnormalities in a mouse model of mitochondrial abnormalities in a mouse model of Rett syndrome.Rett syndrome. Mol Cell Biol, 2006. Mol Cell Biol, 2006. 2626(13): p. 5033-(13): p. 5033-42. RETT SYNDROME42. RETT SYNDROME

Divergent EvidenceDivergent Evidence

1.1. Filipek, P.A., et al., Filipek, P.A., et al., Relative carnitine Relative carnitine deficiency in autism.deficiency in autism. J Autism Dev Disord, J Autism Dev Disord, 2004. 2004. 3434(6): p. 615-23. NONSPECIFIC MITO (6): p. 615-23. NONSPECIFIC MITO DYSFUNCTIONDYSFUNCTION

2.2. Poling, J.S., et al., Poling, J.S., et al., Developmental regression Developmental regression and mitochondrial dysfunction in a child with and mitochondrial dysfunction in a child with autism.autism. NONSPECIFIC MITO DYSFUNCTION NONSPECIFIC MITO DYSFUNCTION

3.3. J Child Neurol, 2006. J Child Neurol, 2006. 2121(2): p. 170-2. Tsao, (2): p. 170-2. Tsao, C.Y. and J.R. Mendell, C.Y. and J.R. Mendell, Autistic disorder in 2 Autistic disorder in 2 children with mitochondrial disorders.children with mitochondrial disorders. J Child J Child Neurol, 2007. Neurol, 2007. 2222(9): p. 1121-3. CO Q10 (9): p. 1121-3. CO Q10 DEFICIENCY AND THE OTHER NONSPECIFIC DEFICIENCY AND THE OTHER NONSPECIFIC RC DYSFUNCTION II/III & IVRC DYSFUNCTION II/III & IV

Mitochondrial AutismMitochondrial Autism—Immediate Clinical —Immediate Clinical Research PrioritiesResearch Priorities11

Sib studies—biomarkers, growth Sib studies—biomarkers, growth characteristics, phenotypic spectrumcharacteristics, phenotypic spectrum

1.1. Are biochemical markers detectable at Are biochemical markers detectable at birth or shortly thereafter?birth or shortly thereafter?

2.2. If yes, what is inheritance pattern—If yes, what is inheritance pattern—doubt mtDNA?doubt mtDNA?

3.3. If no, when do biomarkers appear, and If no, when do biomarkers appear, and what is trigger or developmental what is trigger or developmental biochemical pathway maturation cycle?biochemical pathway maturation cycle?

Mitochondrial Autism—Mitochondrial Autism—Immediate Clinical Immediate Clinical Research PrioritiesResearch Priorities22

Longitudinal case studies/high riskLongitudinal case studies/high risk Biochemical markers vs. timeBiochemical markers vs. time Muscle biopsy, skin, leukocytesMuscle biopsy, skin, leukocytes Clinical correlations with Clinical correlations with

regressionsregressions

Study that should be done Study that should be done STAT STAT

Proposed selection criteria for Proposed selection criteria for Genome wide DNA microarray Genome wide DNA microarray analysis (NB ‘mito autism’ may analysis (NB ‘mito autism’ may not be good enough not be good enough endophenotype)endophenotype)

1.1. Family with 2+ offspring on ASD Family with 2+ offspring on ASD spectrumspectrum

2.2. Biochemical fingerprint markers Biochemical fingerprint markers positive—fasting PAA with inc positive—fasting PAA with inc alanine/lysine, increased fasting alanine/lysine, increased fasting lactate, increased AST with nL ALTlactate, increased AST with nL ALT

3.3. One pt with regressive autism One pt with regressive autism associated with growth failure.associated with growth failure.

4.4. Motor findings also present Motor findings also present including hypotonia and weaknessincluding hypotonia and weakness

Mitochondrial Autism—Mitochondrial Autism—Immediate Clinical Immediate Clinical Research PrioritiesResearch Priorities33

Treatment trials—dietary Treatment trials—dietary manipulation, immune manipulation, immune challenge avoidance, fever challenge avoidance, fever treatment, rescue therapy treatment, rescue therapy trialstrials

Cybrid mitochondrial platelet Cybrid mitochondrial platelet studies—determines studies—determines contribution of mtDNA to contribution of mtDNA to disorderdisorder

Mitochondrial Autism—Mitochondrial Autism—Epidemiology & Epidemiology & Population Future Population Future StudiesStudies

Environmental exposures—pollutants, Environmental exposures—pollutants, ecological studies, vaccination history, ecological studies, vaccination history, infection history, nutritional variablesinfection history, nutritional variables

Mitochondrial/Metabolic Disorders Mitochondrial/Metabolic Disorders Vaccination registry to systematically Vaccination registry to systematically study susceptible subpopulations who study susceptible subpopulations who may need alternative schedule. There may need alternative schedule. There are no safety studies to date on at risk are no safety studies to date on at risk populations.populations.

1.1. Brady, M.T., Immunization recommendations for children with metabolic Brady, M.T., Immunization recommendations for children with metabolic disorders: more data would help. Pediatrics, 2006. 118(2): p. 810-3.disorders: more data would help. Pediatrics, 2006. 118(2): p. 810-3.

2.2. Kingsley, J.D., et al., Immunizations for patients with metabolic disorders. Kingsley, J.D., et al., Immunizations for patients with metabolic disorders. Pediatrics, 2006. 118(2): p. e460-70.Pediatrics, 2006. 118(2): p. e460-70.

3.3. Yang, Y., et al., Acute metabolic crisis induced by vaccination in seven Chinese Yang, Y., et al., Acute metabolic crisis induced by vaccination in seven Chinese patients. Pediatr Neurol, 2006. 35(2): p. 114-8.patients. Pediatr Neurol, 2006. 35(2): p. 114-8.

Concession—Dr. FryeConcession—Dr. Frye

Prior Epidemiology—Prior Epidemiology—Evidence of Absence is Evidence of Absence is not Absence of Evidencenot Absence of EvidenceStudyStudy Estimated statistical power of the largest Estimated statistical power of the largest

population based study by Madsen et al. population based study by Madsen et al. refuting the association between Autism and refuting the association between Autism and vaccines. vaccines.

The effect size and power are calculated for The effect size and power are calculated for four different proposed percentages of the four different proposed percentages of the Autism population at risk for vaccine Autism population at risk for vaccine associated regressive Autism. associated regressive Autism.

Two difference population prevalences are Two difference population prevalences are used: the actual population prevalence of the used: the actual population prevalence of the Danish study and the current estimated Danish study and the current estimated population prevalence in the U.S. population prevalence in the U.S.

Power AnalysisPower Analysis

Percent ofAutism Populat

ion

1:1273 Prevalence 1:150 Prevalence

Effect Size

PowerEffect

SizePower

7 0.0020 24.1% 0.0059 97.9%

5 0.0014 13.8% 0.0041 77.4%

3 0.0009 8.4% 0.0025 35.7%

1 0.0003 5.4% 0.0008 7.7%