HLA-DR genotypes in familial rheumatoid arthritis: increased frequency of protective and neutral alleles in a multicase family.

OBJECTIVE: We describe a unique family where each of the 5 siblings in the second generation has rheumatoid arthritis (RA). Two other members of the family have RA and systemic lupus erythematosus (SLE), respectively. No members of previous generations in the family had documented inflammatory arthritis. Due to the suspected genetic predisposition, HLA-DR genotypes were determined in the affected siblings and their parents, children, and grandchildren. We investigated the possible role of various HLA-DR alleles in the evolution of RA in this multicase family. METHODS: HLA-DRB1* alleles were determined by polymerase chain reaction using the sequence-specific primer-Olerup method. RESULTS: The most common alleles in the 6 persons with RA were HLA-DRB1*07 and DRB1*15, which are known to be protective and neutral in RA. No patient or family member carried any HLA-DR4 alleles. CONCLUSION: HLA-DRB1*07 and DRB1*15 alleles are thought to be protective or neutral in RA. However, the majority of RA patients in the family and nearly half of all family members carried these alleles, suggesting a role of these genotypes in susceptibility to RA. No RA patient in this family carried HLA-DR4 alleles. Thus, in our rare family with 6 RA cases, an unexpected genetic background may be involved in the increased susceptibility to inflammatory arthritis.

Tumour necrosis factor-alpha and heat-shock protein 70-2 gene polymorphisms in a family with rheumatoid arthritis.

OBJECTIVES: The aim of this work was to investigate the prevalence of TNF-alpha-308 polymorphism among the 29 members of a family with RA and the association between the MHC-linked biallelic HSP70-2 gene and the TNF-alpha polymorphism. Five of the members with RA were diagnosed by using the revised 1987 ACR criteria, and 1 member suffered from SLE. METHODS: The variations in the TNF-alpha and the HSP70-2 genotypes were analyzed by PCR-RFLP, using NcoI and PstI restriction enzymes. RESULTS: Two of the 29 members were homozygotes for allele A, 18 were heterozygotes (TNF A/G) and 9 of them were homozygotes for allele G. Nineteen of the 29 were heterozygotes for HSP70-2 (A/G), 10 of them were homozygotes for the G allele, and none were homozygotes for allele A. Four of the 5 the RA patients carried the A allele for TNF-alpha all 5 were heterozygotes for HSP70-2 genotypes. CONCLUSION: The carriage of the A allele for TNF-alpha of -308 SNP in 4 of the 5 RA patients, and the high prevalence (68.0%) of TNF A allele carriers in this family confirms the important role of this candidate gene in the pathomechanism of RA, and might be of prognostic value for future clinical observations. Further, to test for association a much larger set of genetically independent patients and controls is needed.