Deletion polymorphism in the angiotensin I converting enzyme (ACE) gene as a genetic risk factor for sarcoidosis

Background - Genetic control of serum angiotensin I converting enzyme (SAGE) levels has been suggested. A study was undertaken to elucidate the role of this polymorphism in sarcoidosis. Methods - Three hundred and forty one unrelated healthy controls and 103 consecutive patients with sarcoidosis participated in the study. SAGE levels and an insertion/deletion (I/D) polymorphism in intron 16 of the ACE gene were studied in each subject and new reference intervals for SAGE activity for each genotype were determined. The difference in genotype and allele frequencies between controls and patients was analysed and odds ratios were calculated to estimate the relative risk. Results - A significant association was seen between ACE gene polymorphism and SAGE levels in both patients and controls. The new reference intervals for each genotype discriminated abnormal SAGE levels in patients more accurately, especially those with genotype II. In women the frequencies of allele I were 0.68 (allele D 0.32) in controls and 0.58 (allele D 0.42) in patients, and the difference between the two female groups was significant (p < 0.05). Thus, an excess of genotype ID or DD was observed in female patients (odds ratio 2.18; 95% confidence interval 1.18 to 4.01; p = 0.01). Conclusions - These findings suggest that ACE gene polymorphism is associated with SAGE levels in both patients with sarcoidosis and controls. ACE gene polymorphism should be further evaluated as a candidate marker for an increased risk of sarcoidosis.