This finding is noteworthy because AIFM1 mutations are also associated with mitochondrial encephalomyopathy, prenatal ventriculomegaly and Cowchock syndrome, three disorders characterised by developmental disabilities, motor dysfunction, muscle weakness and brain abnormalities as resolved by MRI.11–13 Our work expands the spectrum of AIFM1-associated phenotypes and mandates screening of AIFM1 in small pedigrees with apparent autosomal-recessive ANSD if X-linked inheritance cannot be excluded. The gene discussed is AIFM1; the disease is X-linked Charcot-Marie-Tooth disease type 4.