Alopecia areata, autoimmunity, and Down's syndrome.

Alopecia areata occurs more often in Down's syndrome than would be expected by chance, sixty cases being found among 1000 patients with this syndrome compared with one case among 1000 subnormal controls. Because alopecia areata is associated with some organ-specific autoimmune disease and thyroid antibodies are often found in Down's syndrome sera from affected patients were examined for the presence of fluorescent autoantibodies. Antibodies against thyroid components tended to be present in female mongols with alopecia areata in comparison with females in a normal population but not in male mongols. Futhermore, eight out of 23 female mongols (35%) with alopecia areata had antibodies against thyroid components compared with two out of 23 female mongols (9%) without alopecia areata.