Congenital hypotrichosis due to short anagen

Two children with congenital hypotrichosis are described. Both presented wi th persistent short, fine hair since birth. Evidence is provided that the s hort hair observed in these patients is due to a short anagen phase of the hair cycle, with a normal rate of hair growth. Shortening of the anagen pha se of the scalp hair cycle leads to a decrease in the maximal hair length a nd an increase in the number of hairs in telogen, resulting in an increase in hair shedding. Scanning electron microscopy showed a widely spaced cutic ular pattern, a finding typically seen in hair of thin calibre. One patient had affected family members with an apparently autosomal dominant mode of inheritance, The disorder appears to resolve spontaneously during puberty a nd adulthood.