OBJECTIVETo study the association between vitamin D receptor (VDR) gene Apa I polymorphism and vitamin D deficiency rickets in children of Shanxi Han ethnic group, and to explore the significance of individual hereditary factors in the development of rickets.

METHODSThis was a case control study. The grouping criteria were serum 25(OH)D(3) level, blood bone alkaline phosphatase and clinical symptom, respectively. The laboratory test methods were enzyme linked immunoassay and radioimmunoassay. PCR-RFLP technology was applied to examine VDR gene Apa I site polymorphism and Hardy-Weinberg hereditary balance test was used to examine the coincidence of gene distribution.

RESULTSFrequencies of AA, Aa and aa genotypes were 5.0%, 52.5% and 42.5% in the rickets group and 4.4%, 55.9% and 39.7% in the control group, respectively. Frequencies of A and a genotypes were 31.3% and 68.7% in the rickets group and 32.3% and 67.7% in the control group, respectively. There was not significant difference in the frequency distribution of VDR genotype and allelic genes between two groups (chi(2) = 0.089, P > 0.05; chi(2) = 0.028, P > 0.05). There was significant difference in the serum 25(OH)D(3) between two groups (t = -8.919, P < 0.01).

CONCLUSIONThe distribution of VDR gene Apa I polymorphism in children of Han ethnic group is balanced relatively. The Frequency of a allelic genes is 67.7% which is therefore the superior gene. VDR gene polymorphism might not be important in an individual's susceptibility to development of vitamin D deficiency.