However, for at least three structural genes, it is noteworthy that (a) keratin c29 is highly homologous to K17, whose absence causes premature Mx apoptosis and alopecia in mice [22]; (b) skin lacking Cldn1 (claudin 1) displays abnormally short hairs [23]; and (c) Gsdm (gasdermin) mutations have recently been linked to alopecia in mice [24]. Here, CLDN1 is linked to alopecia.