title: [The spontaneous YMDD mutation rate in chronic hepatitis B patients].
abstract: OBJECTIVE
  To investigate the spontaneous YMDD mutation rate.
  
  
  METHODS
  Serum samples collected from 196 untreated chronic HBV patients were detected by primer-specific real-time PCR.
  
  
  RESULTS
  Among 196 patients, spontaneous YMDD variants were detected in 21 subjects (20 YVDD mutants and 1 YIDD mutant). YMDD variants account for more than 50%, 25% to 50%, 9% to 25% of total virus load in 1, 5 and 15 patients, respectively. Gender, age, HBeAg status, serum viral load, the state of disease and duration of infection were not associated with spontaneous YMDD mutation. Genotype B had higher spontaneous YMDD rate than genotype C (20.00% vs 7.38%, x(2) = 6.28, P < 0.05).
  
  
  CONCLUSIONS
  Spontaneous YMDD variants exist in chronic hepatitis B patients, Genotype B is associated with higher spontaneous YMDD rate.
authors.affiliation: Department of Infectious Disease, Changzheng Hospital, Second Military Medical University, Shanghai 200003, China.
authors.forename: Xiao-chun
authors.initials: XC
authors.lastname: Min
authors.forename: Xiao-hui
authors.initials: XH
authors.lastname: Miao
authors.forename: Shu-min
authors.initials: SM
authors.lastname: Zhao
authors.forename: Ke-kai
authors.initials: KK
authors.lastname: Zhao
authors.forename: De-gang
authors.initials: DG
authors.lastname: Yang
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D017931:DNA Primers; D004279:DNA, Viral / Q000032:analysis* / Q000097:blood / Q000235:genetics; D005260:Female; D005838:Genotype; D006515:Hepatitis B virus / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000821:virology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D009154:Mutation; D016133:Polymerase Chain Reaction / Q000379:methods; D012680:Sensitivity and Specificity; D019562:Viral Load; D055815:Young Adult
chemical_list: D017931:DNA Primers; D004279:DNA, Viral