Hypotrichosis simplex of the scalp (HSS) has manifestation of diffuse progressive hair loss that is confined to the scalp. Prevalence is unknown but HSS has been described in multiple members (males and females) of several large families. Progressive hair loss generally begins during the first decade of life and most patients are completely bald by the third decade of life. Body, axillary and facial hair, as well as the eyebrows and eyelashes are unaffected. There are no anomalies of the skin, nails and teeth. The causative gene CDSN (encoding the keratinocyte adhesion molecule, corneodesmosin) has been mapped to chromosome 6p21.3. Transmitted in an autosomal dominant manner.