RESUMO
<p><b>OBJECTIVE</b>To study the genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) among the Han, Buyi and Miao populations in Guizhou and to provide genetic data for establishment of the genetic polymorphism bank of Guizhou Minorities.</p><p><b>METHODS</b>The technique of polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) was used to detect the genotype and allele frequencies at two mononucleotide sites (677 and 1298) of MTHFR among the Han population in Libo county, the Buyi population in Libo county and the Miao population in Leishan county.</p><p><b>RESULTS</b>At the site of 677, the T allele frequencies were found to be 22.8%, 16.1%, 10.6%, for the Han, Buyi, Miao populations respectively. At the site of 1298, the C allele frequencies were 28.9%, 39.1%, 48.7% for the Han, Buyi, Miao populations respectively. The frequencies for the combined heterozygote of 677CT/1298AC were 16.66%, 22.7%, 11.1% for the three populations respectively. Moreover, one case with combined homozygote of 677TT/1298CC was seen in the Miao population.</p><p><b>CONCLUSION</b>The polymorphisms of the two mononucleotide sites (677 and 1298) of MTHFR are diverse in different populations. The C allele frequencies at the site of MTHFR 1298 of the Miao population in Leishan county and the Buyi population in Libo county are high, and the C allele frequency in the Miao population is higher than those hitherto reported in literature.</p>