57º Congresso Brasileiro de Genética
Resumos do 57º Congresso Brasileiro de Genética • 30 de agosto a 2 de setembro de 2011
Centro de Convenções do Hotel Monte Real Resort • Águas de Lindóia • SP • Brasil
www.sbg.org.br - ISBN 978-85-89109-06-2
92
Molecular characterization of polymorphisms
in genes related to folate metabolism in a
sample from Rio de Janeiro
Moura, CM1; Gomes, AD1; Quirico-Santos, T2; Amorim, MR3; Costa Lima, MA1.
1
Laboratório de Genética Molecular Humana, Departamento de Genética, Instituto de Biologia Roberto Alcântara
Gomes, UERJ, 2 Laboratório de Patologia Celular e Molecular, Departamento de Biologia Celular e Molecular, Instituto
de Biologia, UFF, 3 Laboratório de Genética Humana, Departamento de Biologia Geral, Instituto de Biologia, UFF
[email protected]
Keywords: Folic acid, Genetic polymorphisms, Molecular analysis, PCR-RFLP, SSLP
Folates accept one-carbon units from donor molecules and pass them on via various biosynthetic reactions. There
are many enzymes involved in the folic acid cycle and several studies propose the disruption in folic acid metabolism
could be associated with an increased risk for some adult and pediatric disorders. The biologically active form of
folate, tetrahydrofolate, plays an important role in a variety of reactions, being involved in the production of nucleic
acids and in the metabolism of amino acids. Genetic variants in these genes could be associated to an abnormal distribution of folic acid cycle intermediates. In this work we characterize allelic and genotypic distributions of dihydrofolate reductase (DHFR) del19pb; methylenetetrahydrofolate reductase (MTHFR) 677C>T; betaine homocysteine
S-methyltransferase (BHMT) 742G>A and transcobalamin II (TCN2) 776C>G in a sample of 87 non-related individuals from Rio de Janeiro. DNA was extracted from buccal epithelial cells from mouthwash samples and polymerase chain reactions were performed to amplify DNA segments containing the polymorphisms. All reactions were
performed in a ﬁnal volume of 15µL in a VERITI termocycler. Ampliﬁed products were visualized in ethidium
bromide stained agarose gels. Two strategies were used to discriminate wild-type and mutant alleles: RFLP analysis
for MTHFR 677C>T, BHMT 742G>A and TCN2 776C>G; and SSLP for DHFR del19pb. We have observed the
following distributions for these four common polymorphisms: DHFR homozygous wild type 0.30, heterozygous
0.54 and homozygous with deletion 0.16; MTHFR CC 0.44, CT 0.50 and TT 0.06; BHMT GG 0.38, GA 0.54 and AA
0.08; TCN2 CC 0.42, CG 0.29 and GG 0.29. Frequencies of mutant alleles were 0.43; 0.31; 0.35 and 0.43 for DHFR,
MTHFR, BHMT and TCN2 respectively. The distribution of genotypes departs from Hardy-Weinberg Equilibrium
only for TCN2 (χ2 = 14.92; DF = 2; P = 0.0006).