Are the maternal gene variants MTHFR: c.665C>T, MTHFR: c.1286A>C, MTR: c.2756A>G, MTRR: c.66A>G, RFC1: c.80C>T and TCN2: c.776G>C and blood markers of the folate pathway important factors in assessing the risk of fetal trisomy 21 (fetal-T21)? Twenty pregnant women with a high risk and twenty with a low risk of fetal-T21 underwent prenatal examination. Selected gene variants and folate pathway markers and pregnancy-associated plasma protein A (PAPP-A) and free β-subunit of human chorionic gonadotropin β (free-β-hCG) multiple of the medians (MoMs) were determined. The distributions of the alternative alleles and genotypes of the gene variants did not differ between the studied groups. There was no relationship between PAPP-A and β-hCG MoM values and the presence of allele alternative genotype variants. The occurrence of alternative variants of the selected genes and concentrations of most of the studied folate pathway markers may not play a crucial role in the risk of fetal-T21 in pregnant women. However, the relationships between erythrocyte folate concentrations and the occurrence of alternative variants: c.665C>T MTHFR and c.776G>C TCN2, as well as the methylmalonic acid concentration and the occurrence of alternative variant c.776G>C TCN2 in pregnant women with fetal-T21, encourage further research. So far, of the biochemical markers, maternal PAPP-A and β-hCG MoM values remain independent risk factors for fetal-T21.
Keywords: PAPP-A; folate pathway; free β-hCG; gene polymorphism; trisomy 21.