The role of HLA antigens in the manifestation and course of Graves' disease.

Graves' disease is associated with HLA-DR3 in Caucasoids. We have now demonstrated, on the basis of disease-associated MHC haplotypes (A1, Cw3, B8, DR3 and fragments thereof) from 38 families in which more than one member had Graves' disease compared with MHC haplotypes from 56 healthy families, that the risk was highest with the DR locus (relative risk for A1, B8, DR3 = 2.3, for B8, DR3 = 5.3, and for DR3 = 6.8). We further used the sib-pair method to explore linkage of Graves' disease liability to the MHC in 67 affected sib-pairs. The data were consistent with an MHC-linked recessive gene with a frequency of 0.2 to 0.3 and a penetrance of 7.2%; the data, however, accommodated penetrance of up to 16.3%. A recessive model was also consistent with the HLA-B8 genotype distribution in 286 unrelated patients. As the effect of the marker alleles on the course of the disease had been debated several times, we applied a cluster analysis method using 49 clinical and laboratory characteristics, including the HLA-A and HLA-B antigens of 196 patients. Three groups were identified, corresponding to patients with mild disease, Hashitoxicosis and severe (relapsing) disease. The prevalence of HLA-B8 was 8.9%, 21% and 87%, respectively (compared to 18.8% in 380 controls). This suggests the existence of an underlying continuum of genetic liability, apparently related to that for Graves' disease severity, associated with the MHC and mediated through immunoregulatory disturbances.