HBV genotype distribution in Japan and it's clinical significance

日本HBV基因型的地理分布及其临床相关性尚不清楚。采用PCR-RFLP方法对720例日本慢性HBV感染患者进行HBV基因型检测。HBV基因型分为A、B、C、D和混合型，分别占1.7%、12.2%、84.7%、0.4%、1.0%。日本大陆94.2%的患者为基因型C，而冲绳60.0%的患者为基因型b，大陆北部东北地区22.9%的患者为基因型b。与基因型C相比，基因型b患者年龄较大，HBeAg阳性率较低，血清HBV DNA水平较低。以上结果表明，基因型C和B在日本占主导地位，不同基因型患者在地理分布和临床特征上存在显著差异。HBV基因型B和基因型C的临床和病毒学差异尚不清楚。为了评估HBV基因型B和C的差异，我们对年龄和性别匹配的日本慢性HBV基因型B和C患者各50例进行了病例对照研究。在基因型B患者中检测到HBeAg的频率更高，而在基因型C患者中检测到抗hbe的频率较低。基因型B和基因型C患者在nt 1896前区A-to-G突变的发生具有可比性，且与抗hbe相关。核心启动子双突变在C基因型患者中比B基因型患者更常见，且与HBeAg无关。通过多元logistic回归分析，核心启动子双突变与基因型C、年龄35岁及晚期肝病相关，但与性别、HBeAg、HBV DNA或前突变无关。这些结果突出了乙型和丙型HBV感染患者在临床和病毒学特征上的差异。

The geographic distribution of HBV genotypes in Japan and its clinical relevance are poorly understood. 720 Japanese patients with chronic HBV infection was determined HBV genotype by PCR-RFLP. 1.7 %, 12.2 %, 84.7 %, 0.4 %, 1.0 % were classified into HBV genotype A, B, C, D and mixed. 94.2 % of patients in the Japan mainland had genotype C, while 60.0 % of the patients in Okinawa and 22.9 % in the Tohoku, the northern part of mainland, harbored genotype b. Compared with genotype C patients, genotype B patients showed elder age, lower rate of positive HBeAg, lower level of serum HBV DNA. These results indicate tat genotypes C and B are predominant in Japan, and there are significant differences in geographic distribution and clinical characteristics among the patients with the different genotypes. The clinical and virological differences of HBV genotypes B and C are unclear. To evaluate the differences of HBV genotype B and C, we carried out a case-control study in 50 each of Japanese patients chronically infected with HBV genotype B and C, who were matched for age and sex. HBeAg was more frequently detected, while anti-HBe was less common in genotype B than C patients. The occurrence of A-to-G mutation at nt 1896 in the precore region was comparable between genotype B and C patients, and it correlated with anti-HBe. The double mutation in core promoter was more frequent in genotype C than B patients, and did not correlate with HBeAg. By multiple logistic regression analysis, double mutations in core promoter was associated significantly with genotype C, age 35 years and more advanced liver disease, but it was not associated with sex, HBeAg, HBV DNA or the precore mutation. These results highlights differences in clinical and virological characteristics between patients infected with HBV of genotypes B and C.