Interaction between angiotensin-converting enzyme gene rs4343 polymorphism, environment factors, and angiotensin II level on susceptibility to knee osteoarthritis.

OBJECTIVES

Osteoarthritis (OA) is a complex multifactorial disease. The association of knee OA risk with ACE gene rs4343 polymorphism, gene environment synergistic effect, and angiotensin II serum level has not been previously examined. Therefore, we investigate the ACE gene rs4343 polymorphism in knee OA, and its association with severity of knee OA, and angiotensin II serum level.

METHODS

Using a case-control design, we recruited 200 subjects (100 cases and 100 controls) and all were subjected to genotyping of rs4343 SNP by real-time polymerase chain reaction and assay of serum angiotensin II level by ELISA.

RESULTS

G containing genotypes (AG and GG) and G allele frequencies of the ACE rs4343 polymorphism were significantly higher in the case group than that in the control group. There was significant association between ACE rs4343 genotypes and risk of knee OA under the following genetic inheritance models: GG vs. AA (P=0.003), AA vs. GG/AG (P=0.014), AG/AA vs. GG (P=0.037), and G vs. A (P<0.001). Stratified analyses showed ACE rs4343 polymorphism was evidently associated with a significantly increased risk of knee OA among those had BMI≥25% (adjusted OR=3.016; 95% CI 1.052-8.648; P=0.040). Additionally, knee OA patients with GG genotype had greater knee specific WOMAC index, Kellgren score, and serum angiotensin II level than those with AA or GA genotypes.

CONCLUSION

The investigated polymorphism in the ACE gene rs4343 may reflect the risk and severity of knee OA in the Egyptian population, particularly with the GG genotype. The interaction between ACE gene rs4343 polymorphism and obesity further increased the risk of knee OA. Moreover, the higher angiotensin II level may be involved in the pathogenesis of knee OA.