Aim: To investigate the possible relationship of adiponectin (ADIPOQ) gene polymorphisms, plasma adiponectin, and the risk of knee osteoarthritis (OA).
Methods: A total of 398 subjects, 202 knee OA patients and 196 healthy individuals, were enrolled in the case-control study. Genotyping at +45T/G (rs2241766) and +276G/T (rs1501299) loci was performed using polymerase chain reaction-restriction fragment length polymorphism. Plasma adiponectin levels were assessed using enzyme-linked immunosorbent assay. OA severity was determined using the Kellgren-Lawrence (KL) grading system.
Results: No significant associations were observed in the genotype distributions and allele frequencies at two loci of +45T/G and +276G/T polymorphisms in the ADIPOQ between knee OA patients and control subjects. There was a significant association between genotype distribution of +276G/T polymorphism and KL grade 2, 3 or 4 (P = 0.037, P = 0.046, P = 0.016, respectively). At +45T/G locus, the percentage of GG genotype was notably greater in control subjects (13.40%) compared with OA subjects (1.70%) (P = 0.023). Plasma adiponectin was markedly decreased in OA subjects compared with control subjects (P = 0.03). Likewise, circulating adiponectin in OA subjects was notably lesser than that in control subjects in GG genotype of +45T/G (P = 0.029) and +276G/T polymorphisms (P = 0.012).
Conclusion: Polymorphisms +45T/G and +276G/T of the ADIPOQ gene might not be responsible for OA susceptibility among Thais.
Keywords: ADIPOQ; Adiponectin; Knee osteoarthritis; Plasma; Polymorphism.