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[Genetic risk factors of prostate cancer in Han nationality population in Northern China and a preliminary study of the reason of racial difference in prevalence of prostate cancer].

OBJECTIVE
To investigate the genetic polymorphisms of the three major susceptibility genes, AR, VDR, and SRD5A2 genes, in the Han nationality population in Northern China with a low risk of prostate cancer (Pca) and the relationship of these polymorphisms to the susceptibility to Pca, and to discuss the possible reason causing racial difference of prevalence of PCa.


METHODS
Restriction fragment length polymorphism (RFLP) technique and denaturing high-performance liquid chromatography (DHPLC) were used to detect the polymorphic sites in the DNAs from the peripheral blood samples of 116 patients with PCa and 190 normal male controls, all of Han nationality in Northern China. The distribution frequencies of different polymorphic sites were compared with those of the populations with high risk of prostate cancer.


RESULTS
The frequencies of SRD5A2 and VDR genotypes were not significantly different between the Pca patients and the controls (P > 0.05). The frequency of CAG repeat < 22 was significantly higher in the Pca group than in the control group (P < 0.05). Statistical analyses of the AR genotype prevalence showed significant differences between the PCa patients and the controls (P < 0.05). The frequencies of AR, VDR, and SRD5A2 genotypes showed significant difference between the Han population in Northern China and the high-PCa risk populations in Western countries. The frequency of CAG > or = 22 was 80.4% in the Han people in Northern China, significantly higher than that in the US Caucasians (52.1%) and Afro-Americans (25%, both P < 0.001).


CONCLUSION
There is a significant association between the AR gene CAG polymorphisms and PCa in the Han nationality population in Northern China. The distributions of the genotypes of AR, SRD5A2 and VDR gene are different among different ethnic population, which may be one of the reasons causing the racial difference in prostate cancer risk.