OBJECTSTo investigate the distribution of vitamin D receptor (VDR) genotypes among the Hans of a lead contaminated mine in Shanxi and explore the relationship between blood lead levels and the genetic polymorphism of VDR gene.

METHODSVDR genotypes were determined by polymerase-chain-reaction and restrictive fragment length polymorphism (PCR-RFLP) and the blood lead level was measured by using the graphite furnace atomic absorption spectrometry in a population of 120 pre-school children aged 5 - 6 years who were from the mine kindergarten and were unrelated Hans. An environmental questionnaire in relation to blood lead level was filled for each subject.

RESULTS(1) 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 who had VDR B allele [(0.910 8 +/- 0.265 0) micromol/L] was significantly higher than that whose VDR genotype was bb [(0.740 1 +/- 0.270 1) micromol/L (mean +/- standard deviation)] (t = 2.155, P < 0.05). (3) Many factors were found to affect the blood lead levels, such as the VDR genotype, the type of fuel, educational 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.

CONCLUSIONThese results indicated that the frequency distribution of the VDR genotype in these children was apparently different from that in Caucasians who had high frequencies of VDR B. The results also indicated that the individuals carrying the VDR B allele were more susceptible to lead poisoning.