The Journal of rheumatology vol:24 issue:5 pages:856-9
OBJECTIVE: Because of the concurrence, in members of one family, of different autoimmune disorders [rheumatoid arthritis (RA), systemic lupus erythematosus (SLE), psoriasis (PS), and inflammatory bowel disease (IBD)], we investigated the genotypes of each member and compared the results with current knowledge of genetic inheritance of rheumatic and other autoimmune diseases. METHODS: Sera and peripheral blood lymphocytes of 16 family members were collected for HLA typing and investigation. RESULTS: All patients with RA were DR4 positive ad 4 of 5 showed the maternal A2B51DR4 haplotype. Two of 3 siblings with the genotype HLA-A2/3, B8/35, DR2/3 had SLE. Patients with IBD and psoriasis shared the haplotype HLA-A3, B35 CW4 DR2. CONCLUSION: The results show that the important role of patients, sex and confirm the association between HLA haplotype and RA or SLE. They support the hypothesis that autoimmunity is a mendelian dominant trait, and that secondary genes, including these of the major histocompatibility complex, confer phenotypic specificity.