title: The C677T polymorphism of the methylenetetrahydrofolate reductase gene in Mexican mestizo neural-tube defect parents, control mestizo and native populations.
abstract: The C677T mutation of the methylenetetrahydrofolate reductase (MTHFR) gene, associated with the thermolabile form of the enzyme, has reportedly been found to be increased in neural-tube defects (NTD), though this association is still unclear. A group of 107 mestizo parents of NTD children and five control populations: 101 mestizo (M), 50 Huichol (H), 38 Tarahumara (T), 21 Purepecha (P) and 20 Caucasian (C) individuals were typed for the MTHFR C677T variant by the PCR/RFLP (HinfI) method. Genotype frequencies were in agreement with the Hardy-Weinberg expectations in all six populations. Allele frequency (%) of the C677T variant was 45 in NTD, 44 in M, 56 in H, 36 in T, 57 in P, 35 in C. Pairwise inter-population comparisons of allele frequency disclosed a very similar distribution between NTD and M groups (exact test, P=0.92). Among controls, differences between M and individual native groups were NS (0.06<P<0.21), as it was between M and C (P=0.29). A high frequency of the variant was found in H (56%) and P (57%). A similar allele frequency in groups M and NTD does not support a causal relationship between NTD and parental MTHFR C677T genotypes. Thus, the C677T variant cannot be regarded as a major genetic risk factor for NTD in Mexican mestizo parents. Otherwise, C677T in Mexico is very frequent, especially in Huichol and Purepecha natives, as compared with other groups world wide.
authors.affiliation: División de Genética y Medicina Molecular, CIBO, IMSS, Sierra Mojada 800, Colonia Independencia, Jalisco 44340, Guadalajara, Mexico.
authors.forename: I P
authors.initials: IP
authors.lastname: Dávalos
authors.forename: N
authors.initials: N
authors.lastname: Olivares
authors.forename: M T
authors.initials: MT
authors.lastname: Castillo
authors.forename: J M
authors.initials: JM
authors.lastname: Cantú
authors.forename: B
authors.initials: B
authors.lastname: Ibarra
authors.forename: L
authors.initials: L
authors.lastname: Sandoval
authors.forename: M C
authors.initials: MC
authors.lastname: Morán
authors.forename: M P
authors.initials: MP
authors.lastname: Gallegos
authors.forename: R
authors.initials: R
authors.lastname: Chakraborty
authors.forename: F
authors.initials: F
authors.lastname: Rivas
mesh_terms: D004247:DNA / Q000032:analysis; D004252:DNA Mutational Analysis; D005260:Female; D005838:Genotype; D006801:Humans; D008297:Male; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D008800:Mexico / Q000453:epidemiology; D020125:Mutation, Missense / Q000235:genetics*; D009436:Neural Tube Defects / Q000201:enzymology* / Q000208:ethnology / Q000235:genetics; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000097:blood / Q000235:genetics*; D016133:Polymerase Chain Reaction; D011110:Polymorphism, Genetic; D012150:Polymorphism, Restriction Fragment Length
chemical_list: D004247:DNA; D000587:Oxidoreductases Acting on CH-NH Group Donors; D042965:Methylenetetrahydrofolate Reductase (NADPH2)