• estrogen/androgen receptors;
  • knee osteoarthritis;
  • repeat polymorphisms;
  • steroid hormones

Genetic factors have been shown to play an important role in the etiology of osteoarthritis (OA). To elucidate the possible role of genetic variation in the estrogen receptors α and β (ER-α, ER-β) and androgen receptor (AR) genes with knee OA, the -1174(TA)n, c.1092+3607(CA)n, and c.172(CAG)n repeat polymorphisms of ER-α, ER-β, and AR genes were studied. A case–control cohort of 158 patients with idiopathic knee OA and 193 controls were used. A significant difference was observed in the frequency distribution of -1174(TA)9−25 and c.1092+3607(CA)13−27 repeat polymorphisms of the ER-α and ER-β genes between OA patients and controls (p < 0.005 and p < 0.0001, respectively). A significantly increased odds ratio (OR) for knee OA was observed in individuals having long alleles (LL) genotype for ER-α gene and LL and one short and one long allele (SL) genotypes for ER-β gene compared to individuals with the short alleles (SS) genotype (95% CI 1.03–3.5; p = 0.04 and CI 2.4–8.3 and 2.5–7.5; p < 0.001, respectively). When ORs were adjusted for various risk factors, it was observed that women with LL genotypes for ER-β and AR genes showed significantly increased risk for OA development (p = 0.002 and 0.001). An association between c.1092+3607(CA)13−27 and c.172(CAG)8−34 repeat polymorphisms of the ER-β and AR genes and knee OA was found in individuals of Greek descent.