To test for linkage and association to rheumatoid arthritis (RA) in multiplex families for polymorphic markers in candidate gene loci. Loci including the cytokine cluster on 5q31.1 and IL10, both previously investigated in RA, were included along with several other genes including ICAM-1, cMYC, the cytokine cluster on 17q11.2 and IL1RA.
One hundred eighty-five multiplex RA families were genotyped for 11 microsatellite markers close to candidate genes. Markers showing evidence of linkage and/or association to RA were tested in a further cohort of families (n = 99).
A single microsatellite marker in the GSTM4 gene showed some evidence of linkage, LOD 1.6 (p = 0.006). However, there was no evidence of excess allele sharing in the second cohort of families tested. There was also evidence of association to RA, using the transmission disequilibrium test for a dinucleotide repeat in the IRF gene in the cytokine cluster on 5q31.1; this was not replicated in a second cohort of families.
Our results do not provide evidence of a role for these genes in RA susceptibility.