The interaction between PAX9 rs2073244 and passive smoking during pregnancy on low birth weight in newborns: a case–control study

To explore whether rs2073244 at PAX9 increased susceptibility for full-term low birth weight infants and whether indoors passive smoking exposure has a combined effect with rs2073244 on newborn low birth weight (LBW), a 1:2 paired case-control study of LBW newborns was conducted at Xiamen University Affiliated Women and Children's Hospital from March 2010 to October 2013. The rate of indoor passive smoking exposure in the LBW group was higher than it in the NBW group (<i>p</i> = 0.019). GG of PAX9 rs2073244 decreased the risk of LBW [OR = 0.38, 95% CI: (0.15-0.98)] and smaller HC [OR = 0.44, 95% CI:(0.20-0.98)]. The relative excess risk for LBW contributed by the additive interaction between the rs2073244 risk genotypes AG/AA and mother pregnancy passive smoking exposure was 10.679 (95%CI 1.728-65.975). Our study suggested that the AG/AA genotype of PAX9 rs2073244 might be a risk factor for LBW of full-term newborns, especially in maternal passive smoking.