Methylenetetrahydrofolate reductase (MTHFR): the incidence of mutations C677T and A1298C in the Ashkenazi Jewish population.

The polymorphic mutation C677T in the gene of MTHFR is considered a risk mutation for spina bifida and vascular disease. Another common mutation on the MTHFR gene, A1298C, has also been described as another risk mutation. We studied the frequencies of these two mutations on DNA samples from healthy Jewish individuals and compared them to the frequency of these mutations in DNA samples obtained from healthy individuals in South Texas. The presence of the C677T allele was determined by PCR and Hinf I digestion, and mutation A1298C by PCR and Mbo II digestion. A total of 310 alleles was examined for C677T in the Ashkenazi samples and 400 alleles in the non-Jewish samples. The rate of C677T among the Ashkenazi Jewish alleles was 47.7% as compared to 28.7% among the alleles from the non-Jewish population. The difference is statistically significant, P < 0.0005. Mutation A1298C was examined in 298 alleles of Jewish individuals and 374 alleles of non-Jewish counterparts from Texas. The rate of the A1298C mutation in the Jewish samples was 27.2% whereas in the non-Jewish was 35%. This was also statistically significant, P < 0.031. No individuals were homozygous for both mutations or were found to be homozygous for one mutation with heterozygosity of the other mutation, and that the C677T and the A1298C alleles did not occur in cis position. This study shows a unique distribution of C677T and the A1298C alleles among the Ashkenazi Jews. In spite of high frequency of C677T mutation, spina bifida is less common among Ashkenazi Jews. Further studies are needed to establish whether the C677T and the A1298C mutations have an impact on vascular disease in the Ashkenazi Jewish population.
(Copyright 1999 Wiley-Liss, Inc.)