Genetic-based reference values for angiotensin-converting enzyme (ACE) according to I/D polymorphism in a Spanish population sample

Abstract

Serum angiotensin-converting enzyme (ACE) activity has been related to sarcoidosis and other granulomatous diseases. It has been demonstrated that serum ACE activity is influenced by ACE gene I/D polymorphism. The aim of this study was to establish ACE activity reference values according to genotype in a Spanish population to improve diagnostic sensitivity and treatment monitoring in sarcoidosis patients. A sample population of 150 blood donors was included in the study. Serum ACE activity and genotype were determined and the reference intervals, defined as the 95% central range of the population (2.5th-97.5th percentiles) were obtained for all three genotypes (DD, DI, II) and for the entire sample. Genotype frequencies were 37% DD (n=54), 43% DI (n=63), and 20% II (n=30). Individuals with DD genotype showed the highest ACE activity (mean 39.0 U/L, SD 13.6), ID genotype showed intermediate levels (mean 29.5 U/L, SD 10.2) and II genotype lowest levels (mean 19.1 U/L, SD 4.9). ACE activity differed significantly between these groups: F (2144)=33.15, p<0.05. The corresponding reference intervals for ACE activity were 13.3-63.9 U/L in the overall sample, 12.3-65.6 U/L in genotype DD, 9.5-49.5 U/L in DI and 9.6-28.7 in II. The preliminary reference values for ACE activity in healthy Spanish individuals according to I/D polymorphism are presented. Significant differences in these values were found between the genotype groups.