Distribution of HBV genotypes and YMDD mutations in E antigen-positive patients

Objective To investigate the distribution of hepatitis B virus (HBV) genotypes and determine the correlation with YMDD mutations present in those HBV genomes.Methods One-hundred-and-thirty-seven patients with chronic HBV infections and HBV e antigen (HBeAg) -positivity were recruited for study between February 2008 and January 2009.HBV genotypes were detected by real-time PCR, and YMDD mutations were detected by ligase detection reaction (LDR) .Results Twenty-one of the 137 specimens were unsuccessful in genotyping.For the remaining 116 specimens, two (1.7%) were genotype A, 19 (16.4%) were genotype B, 91 (78.5%) were genotype C, and four (3.5%) were genotype D.YMDD mutations were detected in 41 (35.4%) of the specimens, including seven (36.8%) of genotype B, 33 (36.3%) of genotype C, and one (25.0%) of genotype D.Mutation rates were higher in genotypes B and C than in genotype D, but the differences did not reach statistical significance (χ2=0.034, P>0.05) .Among the 41 viruses carrying the YMDD mutation, 60.9% were classified as I mutation, 31.7% as V mutation, and 7.4% as I/V mixed mutation.Conclusion The most frequent HBV genotype in our hospital's chronic HBV population is genotype C, followed by genotype B.The YMDD mutation rates in genotypes B and C were similar, and the mutation rate was not correlated with the genotype.