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218 METHYLENETETRAHYDROFOLATE REDUCTASE (MTHFR) GENE MUTATIONS IN EXTREMELY LOW BIRTH WEIGHT INFANTS.
  1. E. Chen,
  2. K. Yanamandra,
  3. H. Chen,
  4. D. Napper,
  5. J. A. Bocchini Jr,
  6. R. Dhanireddy
  1. Louisiana Health Sciences Center, Shreveport, LA

Abstract

Objective To investigate the role of MTHFR gene polymorphisms in the neonatal outcomes. Mutation in MTHFR gene at position 677 expresses low enzyme activity (677T allele) compared to the wild type (677C allele).

Methods A total of 480 newborn infants were evaluated. Genotyping studies were carried out in the MTHFR gene by microplate RFLP-PCR and the genotypes were stratified by gestation of birth, birth weight, ethnicity etc.

Results In the total neonatal population, the frequencies of MTHFR 677CC (normal genotype), 677CT (heterozygotes), and 677TT (mutant genotype) were 0.82, 0.17, and 0.015, respectively in African Americans; 0.41, 0.45, 0.13, respectively, in Caucasians; and 0.41, 0.36, 0.23, respectively, in Hispanics. The mutant allele frequencies in African Americans, Caucasians, and Hispanics were, respectively, 0.1, 0.36, 0.41. After culling the data, we found that the mutant T allele was significantly five-fold lower in extremely low birth weight (ELBW) (n = 28) infants who weigh less than 1,000 g than in the normal weight (n = 33) infants (0.018 vs 0.095) who weigh more than 3,500 g in the African American community. In Caucasians, the mutant genotype was 2.5-fold lower in ELBW (n = 19) infants compared to the normal weight (n = 10) infants. Comparison of the genotypes in other weight categories yielded nonsignificant differences.

Conclusion Our data on the low prevalence of MTHFR mutant genotype in the extremely low birth weight infants suggest that these infants cannot afford to have the mutation compared to the normal weight infants, the significance of which is at present unknown. The literature on the role of MTHFR genotypes in neonates was very limited. Chen DF et al (2004) studied 250 normal gestational and 250 preterm delivery/LBW Chinese families and concluded that the fetal mutant genotypes were in association with low birth weight infants in Chinese newborns. Our findings were in contrast to those in the Chinese population and found that the mutant genotype was significantly lower in ELBW infants compared to normal weight infants. However, Kalnitsky A et al (1982) reported higher MTHFR enzyme activity in LBW infants compared to normal weight infants, a finding that we confirmed through the genotypes. This is the first report on the association of MTHFR genotypes with the extremely low birth weight in neonates of Caucasian and African American heritage.

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