AIFM1 and alopecia: In this regard, the spontaneously arisen Harlequin (Hq) mutation was first described as an X-linked mutation causing complete alopecia in hemizygous males (Barber 1971), which was subsequently found to be associated with an endogenous ecotropic retrovirus (ERV) integration into the Aifm1 gene (Klein et al. 2002).