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.
The variations in the TNF-alpha and the HSP70-2 genotypes were analyzed by PCR-RFLP, using NcoI and PstI restriction enzymes.
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.
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.