In 2018, a homozygous missense mutation in FDX2 (c.431C>T, p.Pro144Leu) was described in six patients from two unrelated families showing a neurological phenotype involving optic atrophy and nystagmus developed by age 3, followed by myopathy and recurrent episodes of cramps, myalgia, axonal polyneuropathy and muscle weakness in the first or second decade of life (Gurgel‐Giannetti et al. 2018). The gene discussed is FDX2; the disease is Leber hereditary optic neuropathy.