Association of cytosine-adenine repeat polymorphism of the estrogen receptor-beta gene with rheumatoid arthritis symptoms.

The influence of the polymorphism of the estrogen receptor-beta gene, cytosine-adenine (CA) dinucleotide repeat in intron 6, in the occurrence of rheumatoid arthritis (RA) was investigated. Forty-seven RA patients and 36 control subjects with osteoarthritis (OA) were recruited. CA repeat polymorphism was examined using denaturing high-performance liquid chromatography (WAVE DNA Fragment Analysis System). The mean number of CA repeats was significantly higher in RA than in OA patients. Two groups were established: or=22 repeats (long L); and 3 kinds of genotypes (SS, SL, LL) were found. In RA patients, the L allele frequency was higher (OR = 2.03; P