World distribution of the TS33C/844INS68 CBS in cis double mutation: a reliable anthropological marker

Mild hyperhomocysteinemia is associated to mutations either in cystathionin e beta-synthase (CBS) or in 5,10-methylenetetrahydrofolate reductase (MTHFR ) genes. In 1995, Sebastio et al. characterized a 68 bp insertion in cis wi th the most common CBS mutation (T833C) detected in homocystinuric patients . Recently, this double mutation has been detected in Italian and North-Ame rican controls. Compared to a group of patients affected by coronary artery disease, North-American controls showed not statistically significant diff erence. Moreover, Italian controls displayed a microheterogeneity in the mu tant allele frequency distribution depending on their geographical origin ( North or South of Italy). Aim of our study was to evaluate the prevalence o f the double in cis mutation in different populations. We studied 377 healt hy subjects belonging to various human groups. Genomic DNA, extracted from peripheral blood samples, was amplified using specific primers; PCR fragmen ts were digested with BSR I restriction enzyme to detect the double mutatio n. Our data show a significant heterogeneity among the populations studied, therefore this mutation turned out to be a reliable anthropogenetic marker . The distribution of the double mutation will contribute, with other DNA p olymorphisms, to evaluate the genetic admixture of mixed populations such a s Afro-Americans.