Microheterogeneity in the distribution of the 844ins68 in the cystathionine beta-synthase gene in Italy

Cystathionine beta-synthase (CBS) is an important enzyme for methionine met abolism. A common 844ins68 insertion variant in the CBS gene has been descr ibed. This 68-bp duplication of the intron 7-exon 8 boundary within the CBS gene already has been reported to be associated in cis with the T833C muta tion. Heterozygosity for CBS deficiency is considered an important cause of hyperhomocysteinemia that strongly relates to cardiovascular disease, as w ell as homozygosity for another common variant, the C677T mutation of 5,10- methylene tetrahydrofolate reductase. We analysed the prevalence of the 844 ins68 variant in the CBS gene in 595 unrelated apparently healthy individua ls from nine Italian regions and in 133 patients with coronary artery disea se. Our data confirm that the T833C mutation cosegregates in cis with the 8 44ins68 in all carriers of the insertion. Furthermore, no statistical diffe rence was found in the insertion variant allele frequency between controls and coronary artery disease patients. Our study indicates a microheterogene ity in the distribution of the 844ins68 in the Italian population. (C) 1999 Elsevier Science Ltd. All rights reserved.