Folate levels and N(5),N(10)-methylenetetrahydrofolate reductase genotype (MTHFR) in mothers of offspring with neural tube defects: a case-control study.
BACKGROUND
Neural tube defects (NTDs) have been associated with biochemical factors involved in the conversion of homocysteine to methionine as folate deficiency and the mutation 677T in the N(5),N(10)-methylenetetrahydrofolate reductase gene (MTHFR).


METHODS
A case-control study was performed to detect this mutation in 38 unrelated women with NTD deceased products and 31 mothers without antecedents of NTD offspring. All products were born in Nuevo León (northeastern Mexico) during 1997. Erythrocyte and plasmatic folate levels and the genotype of the 677 polymorphism at the MTHFR locus were analyzed in both groups.


RESULTS
Although no significant differences were found in mean blood folate levels, the percentage of women in the case group with erythrocyte folate levels <160 ng/mL was significantly higher than in the control group (75 vs. 51.2%, p <0.05). The proportion of women with plasma folate levels <3.5 ng/mL was higher in the case group (16.2 vs. 0%, p <0.01). Genotype analysis demonstrated a significantly higher proportion of 677T homozygous mothers with NTD products (39.6 vs. 9.1%, p <0.05). Allele frequencies for the 677T mutation were 0.55 and 0.36 for cases and controls, respectively. The odds ratio (OR) for having a NTD product was 6.1 (95%, CI 1.56-23.6) for homozygous 677T mothers vs. homozygous 677C and heterozygous mothers. Significantly low levels of erythrocyte folate were found in the 677C homozygous case group and in plasma folate in the 677C/677T heterozygous case mothers.


CONCLUSIONS
Our study suggests that folate deficiency and MTHFR unfavorable genotype in mothers are important risk factors for severe NTD phenotype in our population.
Martínez de Villarreal
L E
LE
Departamento de Patología, Unidad de Genética y Defectos Congénitos, Facultad de Medicina, Universidad Autónoma de Nuevo León (UANL), Monterrey, Nuevo León, Mexico. laurmart@ccr.dsi.uanl.mx
Delgado-Enciso
I
I
Valdéz-Leal
R
R
Ortíz-López
R
R
Rojas-Martínez
A
A
Limón-Benavides
C
C
Sánchez-Peña
M A
MA
Ancer-Rodríguez
J
J
Barrera-Saldaña
H A
HA
Villarreal-Pérez
J Z
JZ
D000328:Adult; D000483:Alleles; D019943:Amino Acid Substitution; D000757:Anencephaly / Q000209:etiology / Q000401:mortality; D016022:Case-Control Studies; D003062:Codon / Q000235:genetics; D004252:DNA Mutational Analysis; D004912:Erythrocytes / Q000737:chemistry; D005260:Female; D005492:Folic Acid / Q000097:blood*; D005494:Folic Acid Deficiency / Q000201:enzymology / Q000453:epidemiology / Q000235:genetics* / Q000378:metabolism; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006710:Homocysteine / Q000378:metabolism; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D008431:Maternal-Fetal Exchange; D042965:Methylenetetrahydrofolate Reductase (NADPH2); D008800:Mexico / Q000453:epidemiology; D020125:Mutation, Missense; D009436:Neural Tube Defects / Q000209:etiology* / Q000401:mortality; D000587:Oxidoreductases Acting on CH-NH Group Donors / Q000235:genetics*; D011247:Pregnancy; D011248:Pregnancy Complications / Q000201:enzymology*; D011256:Pregnancy Outcome; D012307:Risk Factors; D016135:Spinal Dysraphism / Q000209:etiology / Q000401:mortality
D003062:Codon; D006710:Homocysteine; D005492:Folic Acid; D000587:Oxidoreductases Acting on CH-NH Group Donors; D042965:Methylenetetrahydrofolate Reductase (NADPH2)