Relationships Of Blood Lead Levels With Vitamin D Receptor Gene Polymorphisms Among Pregnant And Non-pregnant Women In Wuhan

Objective:Lead exposure of pregnant women may lead to low birth weight,preterm birth,congenital malformation,stillbirth,and miscarriage.The vitamin D receptor?VDR?gene has been reported to affect blood lead level in both children and lead exposure workers.The objective of this study was to explore the relationship of VDR single nucleotide polymorphisms?SNPs?with blood lead levels and bone turnover measurements in pregnant and non-pregnant women.Methods:Our study is based on cross-sectional design.A total of 973 women,including 234,249 and 248 pregnant women in their 1^st,2^nd and 3^rd trimesters,respectively,and 242 non-pregnant women were recruited at the Wuhan Women and Children Medical Health Center.Blood lead levels?BLLs?were determined using a graphite furnace atomic absorption spectrometer.Osteocalcin?OC?,tartrate-resistant acid phosphatase 5b?TRACP-5b?and 25-hydroxyvitamin D?25?OH?D?levels in plasma were measured by enzyme-linked immunosorbent assay?ELISA?.BsmI,FokI,TaqI and ApaI SNPs of the VDR gene were identified by using TaqMan probes.Results:The geometric mean of BLLs across all subjects was 16.28±1.79?g/L.BLLs and the bone turnover markers we studied?i.e.OC,25?OH?D and TRACP-5b?were significantly different between pregnant and non-pregnant women.Pregnant women showed significantly lower BLLs than non-pregnant women?P<0.001?.The bb genotype for VDR gene BsmI polymorphism was associated with higher OC level compared with BB/Bb genotypes??=0.147,95%CI:0.003–0.290?.Plasma OC level was positively correlated with BLLs among all participants and pregnant women??=0.010,95%CI:0.005–0.015?,while plasma TRAP-5b level was inversely associated with BLLs among pregnant women??=-0.057,95%CI:-0.108–-0.005?.In addition,VDR SNP BsmI,FokI,TaqI and ApaI were not associated with BLLs??=-0.018,95%CI:-0.154–0.119;?=-0.002,95%CI:-0.090–0.087;?=-0.025,95%CI:-0.159–0.109;?=0.071,95%CI:-0.052–0.193?,plasma 25?OH?D levels??=0.478,95%CI:-3.160–4.115;?=0.548,95%CI:-1.805–2.902;?=-1.761,95%CI:-5.325–1.803;?=-1.122,95%CI:-4.389–2.145?,or plasma TRACP-5b levels??=-0.038,95%CI:-0.117–0.040;?=-0.024,95%CI:-0.074–0.027;?=0.007,95%CI:-0.070–0.084;?=0.028,95%CI:-0.042–0.099?among both pregnant and non-pregnant women.Conclusions:Our findings suggest that the contributions of the studied SNP genotypes of VDR gene to BLLs were fairly small among pregnant women in Wuhan who exposed to low level of environmental lead.Prospective studies on high lead-load population should be conducted to explore associations between BLLs with VDR SNPs and bone turnover biomarkers in the future,and use gene chip to screen specific target.