Familial aggregation of alopecia areata.

BACKGROUND: Familial aggregation of alopecia areata (AA) has been previously described, but systematic studies with information obtained directly from family members have yet to be undertaken. OBJECTIVE: We sought to study the pattern of familial aggregation of AA by assessing the affection status of patients' relatives. The study included 206 index patients with a total of 1029 first-degree and 2625 second-degree relatives. METHODS: First-degree relatives were directly interviewed, whereas information on second-degree relatives was obtained by interviewing the index patients and their first-degree relatives. RESULTS: Estimated lifetime risks were 7.1% in siblings, 7.8% in parents, and 5.7% in offspring. The risk in second-degree relatives was slightly higher than the reported population risk. Age at onset in index patients and first-degree relatives was significantly correlated. LIMITATIONS: Using patients drawn from specialized hair clinics may have produced results showing a higher proportion of early onset and severe cases. CONCLUSION: The familial aggregation of AA supports the role of genetic factors in the development of the disease. In addition, our data indicate genetic factors might contribute to the age at onset of AA.

Genetic variation in the human androgen receptor gene is the major determinant of common early-onset androgenetic alopecia.

Androgenetic alopecia (AGA), or male-pattern baldness, is the most common form of hair loss. Its pathogenesis is androgen dependent, and genetic predisposition is the major requirement for the phenotype. We demonstrate that genetic variability in the androgen receptor gene (AR) is the cardinal prerequisite for the development of early-onset AGA, with an etiological fraction of 0.46. The investigation of a large number of genetic variants covering the AR locus suggests that a polyglycine-encoding GGN repeat in exon 1 is a plausible candidate for conferring the functional effect. The X-chromosomal location of AR stresses the importance of the maternal line in the inheritance of AGA.