Detection of angiotensin-converting enzyme gene insertion/deletion polymorphism from paraffin-embedded tissues - The Hisayama study

Previous studies have suggested that archival materials from formalin-fixed paraffin-embedded blocks are unsuitable for most molecular techniques because the extracted DNA can be severely degraded. Therefore, the present study was designed to investigate the accuracy of genotyping for the insertion (I)/deletion (D) polymorphism of the angiotensin-converting enzyme (ACE) gene from paraffin-embedded tissues of autopsy cases from Hisayama Town, Japan. The genotype was determined using the double polymerase chain reaction method and to test the accuracy of the method, the polymorphism was investigated using paraffin-embedded tissues from 18 cases whose ACE genotypes (6 cases for each genotype) were known in advance from analysis of fresh-frozen tissue samples. Genotyping using paraffin-embedded tissues was then determined for 968 autopsy subjects. The genotype could be determined in 16 of the 18 test samples (88.9%) and there was no discrepancy with the results obtained from the fresh-frozen tissues. Of the 968 autopsy cases, the frequency of the DD, ID, and 11 genotypes was 12.4%, 47.3%, and 40.3%, respectively, a distribution that did not deviate from the Hardy-Weinberg equilibrium (chi(2df)(2)=0.67, p=0.72). These findings suggest the accuracy of the present method of ACE genotyping from paraffin-embedded tissues.