The genetic risk for alopecia areata in first degree relatives of severely affected patients. An estimate.

Substantial evidence indicates that genetic factors may have a role in the etiology of alopecia areata (AA). Most studies, however, provide only general information on the familial incidence but fail to specify family relationships. We therefore obtained information on the incidence of AA in first degree relatives of 348 severely affected patients. In 7% one of the parents was affected. Among the siblings of the patients 3% had developed AA, while AA was present in 2% of the children. Taking into account the age of the children, their lifetime risk was calculated to approach 6%. However, a severe type of AA is to be expected only in about 2% of the children. The degree of involvement observed in the patients did not influence the frequency and type of AA present in their first degree relatives.