FDX2 and optic atrophy: In 2018, the homozygous missense mutation c.431 C > T (p.P144L) in FDX2 was described in six patients from two unrelated families with autosomal recessive inheritance of a complex neurological phenotype involving early onset optic atrophy followed in the first or second decade of life by progressive myopathy, recurrent episodes of cramps, myalgia, muscle weakness, and axonal polyneuropathy [6].