This case control study was designed to determine the patterns of angiotensin converting enzyme insertion/deletion (ACE I/D) gene polymorphism in rheumatoid arthritis (RA) patients and healthy controls.
The study population was divided into two groups: the study group included 66 RA patients diagnosed according to the American College of Rheumatology (ACR) classification criteria for RA, and the control group included 66 healthy adults who were age-and sex-matched to the RA group. All RA patients were assessed by Disease Activity Score (DAS28), ACR Classification of Global Functional Disability Status and Sharp's score as outcome measures. Gene investigations for ACE I/D polymorphism were performed by polymerase chain reaction (PCR) in both groups.
The ACE I/D polymorphism was the (D/D) genotype in 60.6% (n = 40) of RA patients, the (I/D) genotype in 31.8% (n = 21) and the (I/I) genotype in 7.6% (n = 5). The frequency of (D) carriage was significantly higher in the RA cases than in the control group (76.5% vs. 53.8%, respectively, P = 0.0002). ACE D allele carriers were at higher risk of RA, 2.8 times higher than (I) carriers and those who had the homozygote (DD) genotype had 5.6 times the possibility of having RA. No correlations were observed between the homozygote (DD) genotype and disease activity or severity in RA patients.
Our study suggests that high frequency of the ACE D allele contributes to the heritability of RA susceptibility compared to other ACE alleles. On the other hand, no association was detected between ACE I/D polymorphism and the severity of RA.