Abstract:
:The common 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism causes decreased activity of this enzyme and can be associated with mild-to-moderate hyperhomocysteinemia in homozygotes, particularly when there is folic acid deficiency, as well as with vascular dementia, arterial thrombosis, venous thrombosis, neural-tube defects, and fetal loss. When folic acid intake is sufficient, homozygotes for MTHFR 677T appear to be protected against colon cancer and acute lymphatic leukemia, and fetuses bearing this genotype have an augmented survival. The distribution of MTHFR 677T is worldwide, but its frequency in different populations varies extensively. In the present study, we addressed the question of whether the MTHFR 677T alteration has an ancestral origin or has occurred repeatedly. We analyzed the frequency distribution of the previously described polymorphism A1298C in exon 7 and of three intronic dimorphisms, in white Israelis (Jews and Arabs), Japanese, and Ghanaian Africans. The 677T allele was, remarkably, associated with one haplotype, G-T-A-C, in white and Japanese homozygotes. Among the Africans, analysis of maximum likelihood also disclosed an association with the G-T-A-C haplotype, although none of the 174 subjects examined was homozygous for MTHFR 677T. These results suggest that the MTHFR 677T alteration occurred on a founder haplotype that may have had a selective advantage.
journal_name
Am J Hum Genetjournal_title
American journal of human geneticsauthors
Rosenberg N,Murata M,Ikeda Y,Opare-Sem O,Zivelin A,Geffen E,Seligsohn Udoi
10.1086/338932subject
Has Abstractpub_date
2002-03-01 00:00:00pages
758-62issue
3eissn
0002-9297issn
1537-6605pii
S0002-9297(07)60277-8journal_volume
70pub_type
杂志文章abstract::Cancer occurrence in 164 families with breast/ovarian cancer and germline BRCA2 mutations was studied to evaluate the evidence for genotype-phenotype correlations. Mutations in a central portion of the gene (the "ovarian cancer cluster region" [OCCR]) were associated with a significantly higher ratio of cases of ovari...
journal_title:American journal of human genetics
pub_type: 杂志文章,多中心研究
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abstract::Numerous case series have addressed the concern that cancer therapy may damage germ cells, leading to clinical disease in offspring of survivors. None has documented an increased risk. However, the methodological problems of small series make it difficult to draw firm conclusions regarding the potential of cancer trea...
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journal_title:American journal of human genetics
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journal_title:American journal of human genetics
pub_type: 杂志文章,meta分析
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journal_title:American journal of human genetics
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journal_title:American journal of human genetics
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journal_title:American journal of human genetics
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更新日期:1995-08-01 00:00:00
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journal_title:American journal of human genetics
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doi:
更新日期:1989-12-01 00:00:00
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journal_title:American journal of human genetics
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更新日期:2005-06-01 00:00:00
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journal_title:American journal of human genetics
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journal_title:American journal of human genetics
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journal_title:American journal of human genetics
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