AIFM1 and X-linked Charcot-Marie-Tooth disease type 4: Childhood‐onset conditions include Cowchock syndrome (i.e. axonal neuropathy associated with deafness and cognitive impairment – CMTX4, MIM#310490),6, 7, 8 cerebellar ataxia with peripheral neuropathy and deafness,9, 10 isolated deafness (MIM#300614),11 and hypomyelinating leukodystrophy with spondylometaphyseal dysplasia (H‐SMD, MIM#300232).12, 13