Forty-four families were studied for the relationships between HLA and systemic lupus erythematosus (SLE). Nine families had more than 1 member with SLE; haplotype sharing between SLE patients within a family was no greater than expected by chance. Fourteen of 236 relatives had antinuclear antibodies (ANA); the frequency of haplotype sharing between SLE patients and ANA-positive relatives was no greater than expected by chance. One HLA-A,B haplotype was shared by 7 of 35 parent pairs, a frequency (20%) significantly greater (P = 0.004) than in 2 groups of normal controls (3.1% and 5 % ) . These data provide evidence for HLA-linked genes operating recessively in the expression of SLE.
Considerable evidence suggests that genetic factors may play some role in systemic lupus erythematosus (SLE). This hypothesis is based on the observations that SLE 1) is more often found among relatives than among unrelated subjects (1,2), 2) is highly concordant in identical twins ( 3 ) , and 3 ) is associated with an increased frequency of certain H L A antigens.
However, the exact genetic marker o r markers has eluded detection, and the mechanism whereby it might influence disease expression is unknown. We under-From the Division of Rheumatology and Immunology and