Hereditary hypotrichosis simplex of the scalp.

We report on a female aged 13 years, whose scalp hair began to disappear at the age of 9 years, leaving only sparse wispy hairs in the parietal-occipital region. Eyelashes, eyebrows and body hair were unaffected. There were no signs of ectodermal dysplasia on the skin, nails, teeth and eyes nor other congenital abnormalities. The family pedigree showed 15 relatives similarly affected according to an autosomal dominant mode of transmission. Clinical, genetic, histological and ultrastructural aspects led to a diagnosis of hereditary hypotrichosis simplex of the scalp (Toribio-Quiñones type).