Thank-you for your request regarding the evaluation of mitochondrial disorder in your child. Athens Neurological Associates is a 9 physician practice serving the neurological needs of the Athens/Northeast Georgia Region. Dr. Poling and his colleagues do not have special expertise in the evaluation of children potentially harboring mitochondrial abnormalities. Additionally, Dr. Poling is not currently accepting new patients outside the Athens area.

We recognize the confusion regarding the diagnosis and treatment of childhood mitochondrial disorders and provide the following information for your assistance. There are still many unknowns, and much more federal research monies are necessary to help families find answers.

Currently, the National Institutes of Health spends only $12 million per year on mitochondrial disorder related research, less than 1% of the total budget. Mitochondrial disorders and their relationship to Autism deserve funding at the highest levels.

Additional information regarding mitochondrial disorders may be found at www.umdf.com under Recommended Reading.

Disclaimer: The following information is provided for informational purposes only, and does not represent specific treatment recommendations for your child. Only through detailed consultation with your physician can accurate testing and treatment recommendations be rendered.

• My child has Autism. How do I know if he/she has a mitochondrial disorder?
• My child has Autism, but no medical evaluation has been performed or recommended?
• How do I treat a mitochondrial disorder?
• What testing can be performed to evaluate for mitochondrial disorder in my child?
• My child has Autism, shouldn't he/she have a muscle biopsy, the 'gold standard' test?
• What other tests may be helpful in the evaluation of children with ASDs, suspected mitochondrial disorder, and no other clearly defined associated medical diagnosis?
• I live in X, where can I go locally to obtain testing?
• Where can I take my child for mitochondrial subspecialty evaluation?
• What is the difference between a mitochondrial disease, disorder, and dysfunction?
• Does mitochondrial dysfunction have a primary or secondary relationship to ASDs?
• My child has a mitochondrial disorder, should I vaccinate?
• What type of future research will further elaborate upon the role of mitochondria in the ASDs?
• References

My child has Autism. How do I know if he/she has a mitochondrial disorder?

There is no definitive way to determine if a child on the autism spectrum harbors a mitochondrial abnormality based on clinical information alone. Certain 'red flags' may be present that increase the chance of finding abnormalities upon further testing. These including: developmental regression (particularly multiple regressions), early growth failure, failure to thrive, decreased muscle tone, myopathic weakness, gastrointestinal abnormalities especially difficult to manage constipation, hearing and vision abnormalities, seizures, primary immune deficiency, and atypical autistic symptoms.

My child has Autism, but no medical evaluation has been performed or recommended?

Autism should really be considered autism(s) as multiple causes for the behavioral syndrome that we now call 'autism' are both known and unknown. Until these diverse subgroups are identified, we recommend a full medical and psychological evaluation of all children with autism spectrum disorders (ASDs). Emerging evidence suggests that disorders of mitochondrial function represent the most common identified medical disease association with Autism 1-6.

How do I treat a mitochondrial disorder?

Although there are no proven therapies based upon randomized clinical trials for children with mitochondrial disorders, their proper diagnosis may lead to vitamin supplement therapies based upon rational biochemistry. (The exception to this rule being trials of the CoQ-10 analog, Idebenone, for patients for Friedreich's ataxia showing prevention of cardiomyopathy) Note; CoQ10 is a supplement not a vitamin, and Idebenone is a CoQ10 analog, so I am not sure if it should be called a vitamin or a supplement.

Treatment also consists of specific precautions to avoid prolonged fasting, dietary recommendations, anesthesia precautions for surgery, and the avoidance of infections as possible. Specific recommendations are also available regarding anti-pyretic (fever) therapy, intravenous hydration, and nutritional supplements during acute illnesses that would otherwise have a harmless course in a normal child.

What testing can be performed to evaluate for mitochondrial disorder in my child?

This is a complex question with a multi-layered approach. There is, at present, no adequate screening test to "rule-out" or "rule-in" a mitochondrial disease. This being said, there are a series of relatively non-invasive blood and urine tests that can be performed to select patients who warrant further evaluation by a mitochondrial subspecialist. Importantly, there is not currently a consensus opinion on what constitutes a thorough 'mitochondrial evaluation.'

• Fasting Blood - (>4hrs, usually overnight)- Complete Blood Count, Comprehensive Metabolic Panel, Creatine Kinase, Vitamin B12, methylmalonic acid, leukocyte CoQ10, acylcarnitine profile, ammonia, lactic acid, pyruvic acid, plasma amino acids (**note that lactic acid, pyruvic acid, and ammonia are particularly prone to sample handling/acquisition errors)

• Urine - (taken as first morning after above brief fast)- urinalysis with pH, organic acids, amino acids, acylcarnitine profile

• Red Flags - Commonly encountered suggesting further analysis required-increased lactate, increased lactate/pyruvate ratio, decreased serum bicarbonate, increased CK or AST suggesting mild metabolic muscle disorder, decreased carnitine, short chain dicarboxylic fatty acids seen on urine organic acid screen (suggests mitochondrial beta oxidation defect), urine organic acids also showing increased fumarate, malate, 3-methylglutaconate, increase alanine relative to lysine (more stable surrogate marker of pyruvic acid seen on plasma and urine amino acid panels), increased glycine, or proline.

  {Alanine/lysine ratio deserves further comment as some experts believe this to be the best non-invasive indicator of oxidative phosphorylation disorder; however, unless specifically calculated (normal ratio 1.5 to 2.5) by the ordering MD, the report will come back as normal from the reference laboratory on the routine amino acid reports.}

**The above tests are relatively good screening tests for disorders of oxidative phosphorylation. Normal results of the above testing does not exclude a mitochondrial disorder. As a general rule, the above tests are more likely to be positive during acute illness (febrile infection) and after fasting. Lab tests trend toward normalization (more false negatives) in older children/adults.**

My child has Autism, shouldn't he/she have a muscle biopsy, the 'gold standard' test?

There are several problems with this question as stated. First of all, there is no 'gold standard' test for mitochondrial disorders. Some patients may only need a single genetic test to identify the genotype associated with syndromic mitochondrial diseases (e.g. MERRF, MELAS, PEO, KSS, MINGIE).

Additionally, the protocols for muscle biopsy specimen handling and respiratory chain enzymology testing vary widely, with very few centers in the U.S. having the expertise to perform both comprehensive and accurate testing. It is the opinion of this author that muscle biopsy should only be performed by subspecialists in centers of excellence, and not locally.

The advantage of muscle biopsy testing, particularly when respiratory chain enzymology is performed is twofold. First, muscle biopsy histology and immunohistochemistry can be a very specific test (few false positives). Secondly, identifying specific enzyme defects in the oxidative phosphorylation chain can help to select vitamin/co-factor supplements which theoretically could be beneficial for your child. The main disadvantage is the invasive nature of the test and usually the child requires a full anesthesia sedation procedure.

Another advantage of muscle biopsy under sedation is that a spinal tap may also be performed. Spinal fluid (CSF) analysis can be helpful for testing of lactate, amino acids, protein (KSS, MELAS, MERRF), neurotransmitter studies, and cerebral folate deficiency (associated with autistic symptoms).

What other tests may be helpful in the evaluation of children with ASDs, suspected mitochondrial disorder, and no other clearly defined associated medical diagnosis?

Genetic testing for MECP2 (Rett), Fragile X, 15q inverted duplication/deletion (Prader-Willi/Angelman syndromes), Purine/pyrimidine disorders testing, mtDNA point mutation analysis (e.g. A3243G as an example of a specific allele analysis or whole gene study), biotinidase, high resolution karyotype and/or comparative genomic hybridization testing, serum lead (toxic to pyruvate dehydrogenase and may mimic metabolic disorder).

I live in X, where can I go locally to obtain testing?

The screening tests listed above for fasting blood and urine may be performed locally by your pediatrician, neurologist, or geneticist. These tests can be accurately performed by most local reference labs as long as CAREFUL AND PROPER sample handling procedures are followed (e.g. avoidance of artifactual lactate elevation by tourniquet effect).

Further testing on muscle biopsy specimens and spinal fluid should only be done at centers with particular expertise in the field.

A list of some laboratories that perform mitochondrial testing can be found at:
http://mitosoc.org/blogs/diagnosis/tissue/

Where can I take my child for mitochondrial subspecialty evaluation?

• Johns Hopkins Kennedy Krieger Institute, Dr. Richard Kelley
• Cleveland Clinic Foundation, Dr. Bruce Cohen, Dr. Marvin Natowicz, Dr. Sumit Parikh
• UCSD, Dr. Richard Haas, Dr. Robert Naviaux, Dr. Bruce Barshop, Dr. William Nyhan
• UC Irvine, Dr. Doug Wallace and Dr. Pauline Filipek
• Children's Hospital of Los Angeles, Dr. Richard Boles
• UCSF, Stanford, CA, Dr. Gregory Enns
• Molecular Neurogenetics, Atlanta GA, Dr. John Shoffner
• Emory University, Atlanta, GA, Dr. Fran Kendall
• Children's Hospital, Pittsburgh, Dr. Amy Goldstein, Dr.Gerard Vockley
• Columbia University, New York, Dr. Salvatore DiMauro, Dr. Michio Hirano, Dr. Darryl DeVivo
• Children's Hospital, Seattle, WA, Dr. Russell Saneto
• TX Children's Hospital, Houston, Dr. Fernando Scaglia
• University of TX Health Science Center, Houston, Dr. Mary Kay Koenig
• University of TX Southwestern, Dallas, Dr. Ronald Haller
• Riley Hospital, Indianapolis, Dr. Bryan Hainline, Dr.Laurence Walsh
• University of Maryland, Dr. Carol Greene
• Children's National Medical Center, Washington, DC, Dr. Andrea Gropman
• Mass General Hospital, Boston, Dr. David Holtzman

What is the difference between a mitochondrial disease, disorder, and dysfunction?

There is no consensus on this answer. The term 'mitochondrial disease' is usually reserved for patients with specific known mutations in mitochondrial or nuclear DNA that are felt to be causative (primary) of the presenting disease manifestations. The terms 'disorder' and 'dysfunction' are less specific and do not necessarily imply that the mitochondrial cytopathy is primary or secondary in the disease process. For example, the drugs AZT (used to treat AIDS), gentamycin (antibiotic than can rarely cause deafness), and MPTP (causes Parkinsonism) are toxic to mitochondria in some individuals, but this process is considered mitochondrial 'dysfunction' not 'disease.'

Does mitochondrial dysfunction have a primary or secondary relationship to ASDs?

The answer is to this question is an unknown, therefore it would not be accurate at this time to define an autistic subgroup as having a mitochondrial 'disease.' Using 'disorder' or 'dysfunction' would be a more accurate characterization at this time.

Evidence in support of a primary role of is that multiple genetic lesions with mitochondrial dysfunction exhibit autistic symptoms7-11. Additional indirect evidence is that complex inheritance patterns and male:female predominance ratios can be explained by a mitochondrial model.

Evidence against mitochondria having a primary role is that several neuroinflammatory and neurodegenerative diseases have mitochondrial 'dysfunction' prominent in there pathological states but may not be mitochondrial 'diseases' (e.g. Lou Gehrig disease, Multiple Sclerosis, Parkinson's etc). This discussion is rarely evolving with our understanding of mitochondrial medicine. For example, the most common cause of familial Parkinson disease is due to a mutation in a gene that codes for a mitochondrial protein, and therefore is a primary mitochondrial 'disease.'

My child has a mitochondrial disorder, should I vaccinate?

The weight of scientific evidence currently suggests that the benefits of vaccination for your child outweigh the risks. In fact, theoretically speaking, children with mitochondrial disorders are at greater risk than typical children for deterioration caused by the natural infections that vaccines aim to prevent.

This being said, a 'one size fits all' approach to immunization may not be appropriate for subgroup of individuals. Common sense would suggest that alternative methods to approach vaccination may have merit in a child with weakened metabolic system.

Special precautions and plans for vaccine related fever, anorexia, and dehydration should be incorporated into the individualized vaccine administration care plan. Weighing the risk-benefit ratio of each vaccine is beyond the scope of this work but clinical judgement would indicate that some vaccines are more important than others-for example being up-to-date on Haemophilus influezae B would probably be more important than rotavirus. Also, in the presence of outbreaks, the benefit of each individual vaccine increases relative to the risk which theoretically remains the same.

For a discussion of how to rationally spread out vaccines, I would recommend the Vaccine Book by pediatrician Dr. Bob Sears http://www.askdrsears.com/thevaccinebook/.

The field of vaccination safety for special populations is one that is sorely lacking in evidence-based data. More research and safety registries specifically enrolling children with metabolic disorders will be required to properly answer the above questions. 12-15

What type of future research will further elaborate upon the role of mitochondria in the ASDs?

"Baby sibling" studies of mitochondrial autism cases will be very important to further characterize metabolic biomarkers, possible at an age before 'normal' sibling manifests any autistic behavioral symptoms. If this metabolic weakness can be defined at birth, it would be strong evidence of an inherited inborn error of metabolism or susceptibility rather than a toxic insult causing the mitochondrial abnormality. Because of the high heritability of ASDs, this type of study should not require more than several hundred individuals.

Longitudinal metabolic studies of individual cases of mitochondrial autism will be important to better define this clinical phenotype. Anecdotal data suggests a trend toward normalization of biomarkers with age in individual cases. This information will be important, particularly as older autistic individuals seek testing for underlying mitochondrial disorders (rate of false negatives will likely go up with age).

Once the clinical phenotype is well defined, genetic association testing utilizing DNA microarray analysis may yield genetic markers than could be used for screening tests in the larger populations. Biomarker testing in larger populations is logistically problematic, and genetic screening would be preferable.

Once this important mitochondrial subgroup of autism is further delineated, only then can epidemiological studies answer questions related to environmental triggers, dietary factors, and vaccination questions. Past epidemiological studies examining autism are not 'granular' enough to rule-out 'triggered' regressions in this population from any cause, including vaccination.

References

• 1. Shoffner J, Hyams LC, Langley GN. Oxidative Phosphorylation (OXPHOS) Defects in Children with Autistic Spectrum Disorders. In: AAN. Chicago; 2008.
• 2. Oliveira G, Diogo L, Grazina M, et al. Mitochondrial dysfunction in autism spectrum disorders: a population-based study. Dev Med Child Neurol 2005;47:185-9.
• 3. Oliveira G, Ataide A, Marques C, et al. Epidemiology of autism spectrum disorder in Portugal: prevalence, clinical characterization, and medical conditions. Dev Med Child Neurol 2007;49:726-33.
• 4. Kelley RI, Zimmerman AW, Natowicz M. Abnormalities of Mitochondrial Metabolism in Children with Pervasive Developmental Disorder. In: LADDERS Conference. Boston, MA; 2003.
• 5. Filipek PA, Juranek J, Nguyen MT, Cummings C, Gargus JJ. Relative carnitine deficiency in autism. J Autism Dev Disord 2004;34:615-23.
• 6. Poling JS, Frye RE, Shoffner J, Zimmerman AW. Developmental regression and mitochondrial dysfunction in a child with autism. J Child Neurol 2006;21:170-2.
• 7. Pons R, Andreu AL, Checcarelli N, et al. Mitochondrial DNA abnormalities and autistic spectrum disorders. J Pediatr 2004;144:81-5.
• 8. Kriaucionis S, Paterson A, Curtis J, Guy J, Macleod N, Bird A. Gene expression analysis exposes mitochondrial abnormalities in a mouse model of Rett syndrome. Mol Cell Biol 2006;26:5033-42.
• 9. Graf WD, Marin-Garcia J, Gao HG, et al. Autism associated with the mitochondrial DNA G8363A transfer RNA(Lys) mutation. J Child Neurol 2000;15:357-61.
• 10. Filipek PA, Juranek J, Smith M, et al. Mitochondrial dysfunction in autistic patients with 15q inverted duplication. Ann Neurol 2003;53:801-4.
• 11. Eeg-Olofsson O, al-Zuhair AG, Teebi AS, et al. Rett syndrome: a mitochondrial disease? J Child Neurol 1990;5:210-4.
• 12. Draft ISO Scientific Agenda for NVAC Vaccine Safety Working Group, April 4, 2008 In: National Vaccine Advisory Committee (NVAC) Vaccine Safety Working Group for its scientific review on April 11, 2008; 2008; Washington D.C.; 2008. p. 30.
• 13. Yang Y, Sujan S, Sun F, et al. Acute metabolic crisis induced by vaccination in seven Chinese patients. Pediatr Neurol 2006;35:114-8.
• 14. Kingsley JD, Varman M, Chatterjee A, Kingsley RA, Roth KS. Immunizations for patients with metabolic disorders. Pediatrics 2006;118:e460-70.
• 15. Brady MT. Immunization recommendations for children with metabolic disorders: more data would help. Pediatrics 2006;118:810-3.