Associations between ABCG2 gene polymorphisms and isolated septal defects in a Han Chinese population

Breast cancer resistance protein (BCRP) in the placenta, encoded by the ABCG2 gene in humans, plays an essential role in regulating fetal exposure to toxicants and the maintenance of cellular folic acid homeostasis. This study aimed at exploring the associations between 421C>A and 34G>A polymorphisms within the ABCG2 gene of the children and isolated septal defects in a Han Chinese population. An age- and gender-matched case-control study involving 210 pairs was conducted. Genotyping of the ABCG2 gene polymorphisms was performed by sequencing. Forty-six placental tissues and umbilical cords from healthy Han Chinese mothers with uncomplicated pregnancy were collected to investigate the impact of these two polymorphisms on the transcription and translation activities of the ABCG2 gene. The results showed that there were no differences in the genotype distributions and allele frequencies of 421C>A polymorphism. For the 34G>A polymorphism, more cases were carriers of the GA/AA genotypes (adjusted odds ratio [OR]: 1.6, 95% confidence interval [CI]: 1.0-2.3). The ABCG2 mRNA and protein expression did not differ among the three genotypes of 421C>A polymorphism. For the 34G>A polymorphism, the ABCG2 mRNA and protein expression of the GG genotype was significantly higher than that of the AA genotype. In conclusion, 34G>A polymorphism in the ABCG2 gene of the children is associated with isolated septal defects in a Han Chinese population, presumably through regulation of BCRP expression in the placenta.