Genetic influences on spontaneous autoimmune thyroiditis in (CS X OS)F2 chickens.

Genetic effects on spontaneous autoimmune thyroiditis in chickens were assessed by measuring phenotypic symptoms, the titer of circulating antibody to thyroglobulin, and the pathological change in the thyroids of young chicks. One or more loci within the B complex (the major histocompatibility complex of the chicken) are responsible for the expression of autoimmunity, and evidence is provided for an interaction of the B haplotype with genes at other loci. The influence of the B complex component on genetic susceptibility is more visible in animals with limited susceptibility at other loci and becomes indistinguishable as the frequency of other genes determining thyroid autoimmunity increases.