Study On Genetic Susceptibility To Lead Toxicity And Risk Factors Among Different Nationalities

Objective: To investigate the polymorphism distribution of vitamin D receptor gene FokⅠsite and the relationship between polymorphism of FokⅠand lead poisoning, and to analyse the risk factors of lead poisoning among Han, Uygur and Kazak children. Methods: Cluster sampling was used to choose 489 Hans, 499 Uygurs and 525 Kazaks in Urumqi. Blood lead was determined by BH-2100 Atomic Absorption Spectrometer. Polymerase Chain Reaction-Restriction Fragment Length Polymorphism (PCR-RFLP) method was used to analyze the genotype of VDR gene FokⅠsite.Results: 1 The frequencies of FF, Ff and ff genotypes were found to be 38%, 51%, 11% in the Hans , 54%, 38%, 9% in the Uygurs, and49%, 45%, 7% in the Kazaks; the frequencies of allele were found to be 63.4%, 36.6% in the Hans, 72.4%, 27.6% in the Uygurs, and 70.9%, 29.1% in the Kazaks. Significant differences were seen in the frequency distribution of VDR genotype and allele between the Uygurs and the Hans (χ~2=21.90,P<0.05;χ~2=17.26,P<0.05), and significant differences were seen in the frequency distribution of VDR genotype and allele between the Kazaks and the Hans (χ~2=14.54,P<0.05;χ~2=13.43,P<0.05). There were indifferences in the frequency distribution of VDR genotype and allele between the Uygurs and the Kazaks(χ~2=4.75,P>0.05;χ~2=0.58,P>0.05)2 The blood level of Han children were 53.05±2.24μg/L, the mean level of blood lead was 56.72±2.18μg/L in homozygous individuals with F allele, while the mean level of blood lead was 51.44±2.27μg/L in the heterozygous or homozygous with f allele; the blood level of Uygur children were 55.87±2.23μg/L, the mean level of blood lead was 56.88±2.21μg/L in homozygous individuals with F allele, while the mean value was 54.18±2.34μg/L in the heterozygous or homozygous with f allele; the mean level of blood lead of Kazak children were 61.24±1.90μg/L, the mean blood lead level was 63.77±1.82μg/L in homozygous individuals with F allele, while the mean value was 58.12±1.98μg/L in the heterozygous or homozygous with f allele. No statistic correlation between the distribution of FokⅠalleles and the level of blood lead was found in these three populations. 3 In our study, the mean level of blood lead of all of children was 56.57±2.14μg/L, the blood lead concentration of 22.87% of children was more than 100μg/L. The level of blood lead of Kazak children was the highest in the three nationalities, but there are no significances among them. It was the high-risk factors of children's age, parents'education, parents'occupation, bad habits, housing condition, living environment were associated with level of blood lead. Conclusion: A significant difference was seen in the frequency distribution of VDR genotype and allele among the different races. The effect of FokⅠpolymorphism on blood lead levels may not exhibit significant difference in environmental exposured children.