Other genotypes in the cohort in which no epilepsy was found were: PEO1 (n = 13), OPA1 (n = 7), m.14709T>C (n = 5), RRM2B (n = 4), m.12258A>G (n = 2), succinate dehydrogenase deficiency (n = 2), SPG7 (n = 2), m.4298G>A, m.7587T>C, m.7989T>C, m.618T>G, m.12283G>A, m.1624C>T, TYMP, and YARS2 (all n = 1). The gene discussed is RRM2B; the disease is hyperinsulinemic hypoglycemia, familial, 4.