Angiotensin-converting enzyme gene polymorphism in Thai patients with systemic lupus erythematosus.

OBJECTIVE To determine the association between angiotensin-converting enzyme (ACE) I/D polymorphism and the presence of systemic lupus erythematosus (SLE) disease and lupus nephritis (LN), including the association with disease severity in a Thai population. METHOD In this retrospective study, 187 SLE patients followed up for (at least) 7 years in a rheumatology clinic of an academic hospital were enrolled. Disease severity and damage score at diagnosis and every 6 months, including treatment outcome of the first episode of LN were retrieved from medical records. The ACE genotype of SLE patients were determined by polymerase chain reaction and compared with ACE genotype in 687 controls from a database of a Thai surveillance cohort. RESULT There was an association between ACE I/D polymorphism and the presence of SLE disease and LN (P < 0.001). Unexpectedly, the prevalence of DD genotype in SLE patients was lower than controls (OR 0.44 [95% CI 0.23-0.84], P = 0.013). The prevalence of ID genotype was not different between SLE patients and controls (OR 1.44 [95%CI 0.93-2.24], P = 0.102), but was higher in LN patients compared to controls (OR 1.77 [95% CI 1.14-2.72], P = 0.01). However, the ACE I/D polymorphism is not associated with SLE disease severity, either in patients with or without nephritis. CONCLUSION The DD genotype could not be used as a poor prognostic marker for SLE and LN susceptibility in a Thai population. However, ID genotype may be associated with risk to develop LN.