title: Effect of combined mutations in the enhancer II and basal core promoter of hepatitis B virus on development of hepatocellular carcinoma in Qidong, China.
abstract: OBJECTIVE
  To investigate the roles of mutations in enhancer II (Enh II), basal core promoter (BCP) and precore (PC) regions of hepatitis B virus (HBV) in the progression of hepatocellular carcinoma (HCC) in Qidong, China.
  
  
  METHODS
  We conducted a case-control study within a cohort of 2387 male HBV carriers who were recruited between August and September 1996. The HBV DNA sequence was determined in 152 HCC and 131 chronic hepatitis patients. Mutation exchanges during follow up in 115 cases were compared with 108 controls with serum samples taken during a similar length of follow up. In addition, a longitudinal study was conducted in 22 cases in which serial serum samples were available before HCC.
  
  
  RESULTS
  After adjustment for age, history of cigarette smoking and alcohol consumption, hepatitis B e-antigen positivity, T1653, V1753 and T1762/A1764 double mutations were associated with risk of HCC. Multivariate analysis showed that T1653, V1753 and T1762/A1764 double mutations were independent risk factors of HCC. Moreover, a significant biological gradient of HCC risk by number of mutations in Enh II/BCP regions was observed. Paired samples analysis indicated that the increased HCC risk for at-risk sequence mutations were attributable to the persistence of these mutations, but not a single time point mutation. The longitudinal observation demonstrated a gradual combination of mutations in Enh II/BCP regions accumulated during the development of HCC.
  
  
  CONCLUSIONS
  T1653, V1753 and T1762/A1764 double mutations were independent risk factors of HCC. The effect of combined mutations in Enh II/BCP regions increased the risk and persistence of at-risk sequence mutations and was critical for HCC development.
authors.affiliation: Department of Gastroenterology, Affiliated Hospital of Nantong University, Nantong, China.
authors.forename: Li-Shuai
authors.initials: LS
authors.lastname: Qu
authors.forename: Jing
authors.initials: J
authors.lastname: Zhu
authors.forename: Tao-Tao
authors.initials: TT
authors.lastname: Liu
authors.forename: Xi-Zhong
authors.initials: XZ
authors.lastname: Shen
authors.forename: Tao-Yang
authors.initials: TY
authors.lastname: Chen
authors.forename: Zheng-Pin
authors.initials: ZP
authors.lastname: Ni
authors.forename: Run-Zhou
authors.initials: RZ
authors.lastname: Ni
authors.forename: Cui-Hua
authors.initials: CH
authors.lastname: Lu
keywords: hepatitis B virus; hepatocellular carcinoma; mutation