An alternative fast and convenient genotyping method for the screening of angiotensin converting enzyme gene polymorphisms

Abstract

Insertion/deletion (I/D) polymorphisms in intron 16 of the angiotensin converting enzyme gene (ACE) are associated with the plasma angiotensin converting enzyme (ACE) levels, and individuals with the DD allele have been reported to be more susceptible to cardiovascular disease than those without. The conventional genotyping method for the screening of I/D polymorphisms, which involves polymerase chain reaction (PCR)-gel electrophoresis, is laborious and time-consuming. In this study, we assessed the use of TaqMan-PCR genotyping for the screening of I/D polymorphisms as a replacement for the conventional method. We genotyped seven single nucleotide polymorphisms (SNPs) in linkage disequilibrium (LD) with the I/D polymorphisms, and calculated the LD coefficients of the I/D polymorphisms. We found that three polymorphisms, rs4331, rs4334 and rs4341, exhibited the highest LD coefficients (D' = 1.000; r2 = 0.967) and that the genotyping of rs4341 by the TaqMan-PCR method yielded the best discrimination among the different genotypes. Genotyping of 511 samples took only 2 h and the amount of DNA required for each test was only 6 ng by the TaqMan-PCR method using rs4341. In the course of this study, we identified a novel additional polymorphism (a deletion of six amino acids) in exon 13, near rs4316. The deletion allele encoded the testicular ACE, but not the plasma ACE. We concluded that genotyping of the rs4341 ACE polymorphism by the TaqMan-PCR method is a fast and convenient alternative method for direct I/D genotyping. We also concluded that testicular ACE may manifest a deletion of six amino acids that may result in deleterious function of this enzyme.