Alpers Huttenlocher Natural History Study

Inclusion Criteria: * All individuals of any age with confirmed Alpers Huttenlocher Syndrome (AHS) or siblings of confirmed AHS patients are eligible to participate. AHS requires the presence of polymerase gamma 1 (POLG) pathological mutations, either homozygous or compound heterozygote mutations, and the presence of epilepsy and either, developmental regression or hepatopathy. If POLG mutations are not demonstrated, AHS requires the presence of refractory seizures, developmental regression, and hepatopathy as well as two or more other clinical and laboratory findings including elevated cerebrospinal fluid (CSF) protein, neuroimaging showing lactate peaks, reduced N-acetyl aspartate with hyperintensities on T2/FLAIR in the thalamus and posterior head regions, optic atrophy/cortical blindness, quantitative mtDNA reduction (\>30% ) in muscle and/or liver, non-specific electron transport chain (ETC) enzyme deficiencies. * All patients must agree to participate in the North American Mitochondrial Disease Consortium (NAMDC) Clinical Registry Exclusion Criteria: * Patient does not have confirmed AHS and is not the sibling of a patient with confirmed AHS * Not willing to participate in the NAMDC clinical Registry