Affiliations: Departamento de Genética, Universidade Federal
do Rio Grande do Sul, Porto Alegre, Brasil | Programa de Pós-Graduação em
Genética e Biologia Molecular, Universidade Federal do Rio Grande do
Sul, Porto Alegre, Brasil | Serviço de Genética Médica,
Hospital de Clínicas de Porto Alegre, Porto Alegre, Brasil
Note: [] Corresponding author: Lavinia Schuler-Faccini, Universidade
Federal do Rio Grande do Sul – Departamento de Genética, Caixa
Postal 15031 – Agencia Campus UFRGS, CEP 91501-970 / Porto Alegre, RS,
Brasil. Tel.: +51 33166727; Fax: +51 33167311; E-mail:
[email protected]
Abstract: This study aimed to investigate the role of maternal polymorphisms,
as well as their risk genotypes combinations of MTR A2756G, MTRR A66G, CBS
844ins68, and RFC A80G, involved in folate/homocysteine metabolism, as possible
risk factors for Down syndrome (DS) in Southern Brazil. A case-control study
was conducted with 239~mothers of DS children and 197~control mothers. The
investigation of polymorphisms was performed by PCR and PCR-RFLP. The
distribution of genotypic variants was similar in both groups when they were
analyzed separately. An investigation of combined risk genotypes showed that
the risk of having a DS child for one, two or three risk genotypes was 6.23,
6.96 and 5.84 (95%CI 1.48–26.26; 1.69–28.66; 1.37–24.86),
respectively. The combined MTRR 66G and MTHFR 677T alleles were significantly
more common among mothers of children with DS than among control mothers (OR
1.55; IC 95% 1.03–2.35). The results show that individual polymorphisms
studied in this work are not associated with DS; however, the effects of the
combined risk genotypes among MTR, MTRR, CBS and RFC genes are considered
maternal risk factors for DS offspring in our population.
Keywords: Down syndrome, folate, MTR, MTRR, CBS, RFC
