Human Medical Genetics Program, Department of Medicine, University of Colorado Health Sciences Center, 4200 East Ninth Ave., B161, Denver, CO 80262, USA.
Generalized vitiligo is a common autoimmune disorder in which patchy loss of skin and hair pigmentation results from loss of pigment-forming melanocytes from the involved regions. Vitiligo occurs with a frequency of about 1% in most populations, and is highly associated with other autoimmune disorders, particularly Hashimoto thyroiditis. Most cases of vitiligo are sporadic, although some cases cluster in families, and the disorder is thought to be oligogenic in origin. We have studied a large family cluster in which vitiligo and Hashimoto thyroiditis occur in numerous individuals. A whole-genome scan of 24 family members, including 14 affected with autoimmune disease, showed significant linkage of an oligogenic autoimmune susceptibility locus, termed AIS1, to a 14.4 cM interval in 1p31.3-p32.2. A two-locus analysis of Hashimoto thyroiditis in family members segregating an AIS1 susceptibility allele showed suggestive linkage to markers in chromosome 6p22.3-q14.1, in a region spanning both the major histocompatibility complex and AITD1, a susceptibility locus for autoimmune thyroid disease. Our results indicate that the 1p AIS1 locus is associated with susceptibility to autoimmunity, particularly vitiligo, in this family, and that a chromosome 6 locus, most likely AITD1, may mediate the occurrence of Hashimoto's thyroiditis in AIS1-susceptible family members.