Our study increases the range of clinical presentations associated with mutations in POLG gene, underlining some peculiar clinical features, such as PEO associated with corneal edema, and epilepsy, severe neuropathy with achalasia.
Finally, we simplify the classification of POLG-related disease in children using epilepsy as the crucial defining element; we show that Alpers and myocerebrohepatopathy spectrum follow different outcomes and that they manifest different degrees of respiratory chain dysfunction.
Treatment of epilepsy in patients with a POLG1 compound heterozygous A467T/W748S genotype is very challenging; the epilepsy may preferentially respond to sodium channel blockers.
Our cases underscore several important findings: POLG mutations have been observed in every ethnic group studied to date; early predominance of epileptiform discharges over the occipital region is common in POLG-induced epilepsy; the EEG and MRI findings varying between patients and stages of the disease; and VPA dosing at any stage of Alpers-Huttenlocher syndrome can precipitate liver failure.
Different mutations, or combinations of mutations, in POLG1, the gene encoding pol gammaA, the catalytic subunit of mitochondrial DNA polymerase, are associated with a spectrum of clinical presentations including autosomal dominant or recessive progressive external ophthalmoplegia (PEO), juvenile-onset ataxia and epilepsy, and Alpers-Huttenlocher syndrome.