The Association Among VitaminD Receptor Gene Polymorphism, Bone Metabolism And The Susceptibility Of Lead To Children

Objects To investigate the distribution of VDR genotypes among the Hans of a lead contaminated mine in Shanxi and explore the relationship among blood lead levels , urine calcium and the genetic polymorphism of vitaminD receptor (VDR) gene.Methods VDR genetypes were determined by polymerase-chain-reaction and restrictive fragment length polymorphism (PCR-RFLP) and the blood lead level was measured by the method of the graphite furnace atomic absorption apectrometry and the serum osteocalcin (OC) and bone alkaline phosphatase (BALP)was also measured in a population of 120 Pre-school children aged 5-6 years who were from the mine kindergarten and were the Hans without blood relation. An environmental questionnaire in relation to blood lead level was filled for each subject.Result (l)The gene distribution of the VDR phenotypes in these children was VDRBB, 1. 7% ; VDRBb, 9. 2%; VDRbb, 89.2%. (2)The mean blood lead level of the children whohad VDR B allele [(0.91 0.27 ) mol/L] was significantly higher than those whose VDR genetype were bb [(0. 74 0. 27) mol/L] (t = 2. 155, P><0. 05 ) .(3)Many factors were found to affect the blood lead levels, such as the VDR genetype, the type of fuel , educatonal level of mothers and so on. After controlling the possible confounding variables by multiple regression , the contribution of the VDR phenotype to the blood lead levels was still statistically significant. (4)The mean serum osteocalcin level of the children who had VDR B allele [(22.35 11.61) ng/mL] was significantly lower than those whose VDR genetype were bb [ ( 32. 72 12. 13 ) ng/mL] (t = 2.924, P><0.05) .But the mean bone alkaline phosphatase level of the children who had VDR B allele[(173. 94 36. 73) U/L [(2.2167 0.7171) mmol/L] was significantly higher than those whose VDR genetype were bb [ (128.70 42.89) U/L] (t = -3.641, /><0.05) . (5) The lead level of these children has correlation with their serum osteocalcin level and bone alkaline phosphatase level.Conclusion These results indicate that the frequency distribution of the VDR genotype in these children were apparently different from that in Caucasians who had high frequencies of B .These results also indicate that individuals earring the VDRB allele are more susceptibleto lead poisoning and their bone metabolism (the osteocalcin level and bone alkaline phosphatase level) will be affected because of the higher lead level.