Franco R F, Araújo A G, Guerreiro J F, Elion J, Zago M A
Department of Clinical Medicine, School of Medicine of Ribeirão Preto, University of São Paulo, Brazil.
Thromb Haemost. 1998 Jan;79(1):119-21.
A recently described mutation in the methylenetetrahydrofolate reductase (MTHFR) gene (a C to T transition at nucleotide 677) is associated with a thermolabile phenotype and decreased enzyme activity. In homozygotes, the mutation is also related to hyperhomocysteinemia and increased risk for atherosclerotic disease and (apparently) venous thrombosis. The prevalence of this mutation in different human populations is unknown. We have investigated the frequency of the 677 C-->T mutation in the MTHFR gene in 337 individuals (674 chromosomes) belonging to four ethnic groups: Whites, African and Brazilian Blacks, Asians and Amerindians. The frequencies of the positive allele among Whites and Asians were similar to those previously reported for Caucasian populations. The positive allele seems to be slightly rarer among the Amerindians (frequency 24.0%) in comparison to Whites and Asians, with a heterogeneous distribution among the five Indian tribes analysed. In contrast, the mutation has a very low prevalence in Blacks, especially among the African Blacks, for whom the mutation was absent in homozygosity. Our data indicate that the 677 C-->T MTHFR mutation has a significantly heterogeneous distribution among different ethnic groups, a fact that may contribute to explain geographical or racial differences in the risk for vascular disease.
最近发现的亚甲基四氢叶酸还原酶（MTHFR）基因中的一种突变（核苷酸677处的C到T转换）与热不稳定表型及酶活性降低有关。在纯合子中，该突变还与高同型半胱氨酸血症以及动脉粥样硬化疾病和（显然）静脉血栓形成的风险增加有关。这种突变在不同人群中的患病率尚不清楚。我们调查了337名个体（674条染色体）中MTHFR基因677 C→T突变的频率，这些个体分属四个种族：白人、非洲裔和巴西黑人、亚洲人和美洲印第安人。白人和亚洲人中阳性等位基因的频率与先前报道的高加索人群相似。与白人和亚洲人相比，美洲印第安人中阳性等位基因似乎略为罕见（频率为24.0%），在所分析的五个印第安部落中分布不均一。相反，该突变在黑人中患病率很低，尤其是在非洲黑人中，纯合子中不存在该突变。我们的数据表明，677 C→T MTHFR突变在不同种族群体中的分布存在显著的不均一性，这一事实可能有助于解释血管疾病风险的地理或种族差异。
