An insertion/deletion polymorphism in the angiotensin I-converting enzyme gene accounting for half the variance of serum enzyme levels.

TLDR

Determining ACE genotype alongside serum levels refines normal versus abnormal ACE value discrimination by providing a genotype‑specific reference interval. A 250‑bp insertion/deletion polymorphism in the ACE gene was identified with an endothelial ACE cDNA probe and used as a genotype marker in 80 healthy subjects whose serum ACE levels were measured. The insertion/deletion polymorphism, with allele frequencies of 0.6 (short) and 0.4 (long), explains 47 % of serum ACE variance, producing markedly higher ACE concentrations in long‑allele homozygotes (≈494 µg/L) compared to short‑allele carriers (≈299–393 µg/L).

Abstract

A polymorphism consisting of the presence or absence of a 250-bp DNA fragment was detected within the angiotensin I-converting enzyme gene (ACE) using the endothelial ACE cDNA probe. This polymorphism was used as a marker genotype in a study involving 80 healthy subjects, whose serum ACE levels were concomitantly measured. Allele frequencies were 0.6 for the shorter allele and 0.4 for the longer allele. A marked difference in serum ACE levels was observed between subjects in each of the three ACE genotype classes. Serum immunoreactive ACE concentrations were, respectively, 299.3 +/- 49, 392.6 +/- 66.8, and 494.1 +/- 88.3 micrograms/liter, for homozygotes with the longer allele (n = 14), and heterozygotes (n = 37) and homozygotes (n = 29) with the shorter allele. The insertion/deletion polymorphism accounted for 47% of the total phenotypic variance of serum ACE, showing that the ACE gene locus is the major locus that determines serum ACE concentration. Concomitant determination of the ACE genotype will improve discrimination between normal and abnormal serum ACE values by allowing comparison with a more appropriate reference interval.