Hereditary hypotrichosis simplex of the scalp

SUMMARY A peculiar variety of hereditary hypotrichosis is described. The abnormality has affected a large family over the course of eight generations. This genealogy is the fullest so far known of hereditary hypotrichosis. The condition is a hypotrichosis limited to the scalp, which first manifests itself in the early school‐years. Afterwards the loss of scalp hair gradually progresses to almost total alopecia. This terminal stage is reached between the ages of 20 and 25 years, and the condition affects males and females in a similar way. From the genetic point of view, the abnormality is transmitted with an autosomal dominant mode of inheritance with full penetrance.