title: Application of hepatitis B virus genotyping and phylogenetic analysis in intrafamilial transmission of hepatitis B virus.
abstract: BACKGROUND
  Infection with hepatitis B virus (HBV) in early life frequently results in persistent infection, and clustering of the chronic infection within a family is common. However, the relative contribution of perinatal mother-to-infant transmission or early horizontal transmission to the intrafamilial clustering of HBV infection remains unclear. Therefore, we used HBV genotyping and phylogenetic analysis to elucidate the modes of intrafamilial HBV transmission in Taiwan.
  
  
  METHODS
  HBV genotypes and serological markers were determined for 103 individuals from 20 families with evidence of clustering HBV infection.
  
  
  RESULTS
  Three patterns of intrafamilial clustering of HBV infection were identified. Among the 20 families, 8 included a hepatitis B surface antigen (HBsAg)-positive mother (pattern I), 7 included an HBsAg-positive father (pattern II), and in the remaining 5, both parents were positive for HBsAg (pattern III). The rates of HBsAg positivity for children of the 3 representative groups of families were 85.7%, 65.4%, and 87.5%, respectively (P = .16). The identical genotyping results between index parent and carrier children indicated that pattern I clustering was caused by maternal transmission, whereas pattern II clustering was caused by paternal transmission. In pattern III clustering, a concordant HBV genotype between carrier children and mother or father was found in 3 and 2 families, respectively. The modes of transmission were confirmed by phylogenetic analysis in 1 family of each pattern.
  
  
  CONCLUSIONS
  In Taiwan, maternal and paternal transmissions are both important in the intrafamilial spread of HBV infection.
authors.affiliation: Department of Gastroenterology, Taipei City Hospital, Taipei, Taiwan.
authors.forename: Chih-Lin
authors.initials: CL
authors.lastname: Lin
authors.forename: Jia-Horng
authors.initials: JH
authors.lastname: Kao
authors.forename: Bing-Fang
authors.initials: BF
authors.lastname: Chen
authors.forename: Pei-Jer
authors.initials: PJ
authors.lastname: Chen
authors.forename: Ming-Yang
authors.initials: MY
authors.lastname: Lai
authors.forename: Ding-Shinn
authors.initials: DS
authors.lastname: Chen
mesh_terms: D000328:Adult; D002353:Carrier State; D005190:Family; D005260:Female; D005838:Genotype; D006509:Hepatitis B / Q000635:transmission* / Q000821:virology*; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000235:genetics*; D006801:Humans; D008297:Male; D010375:Pedigree; D010802:Phylogeny; D011498:Protein Precursors / Q000235:genetics; D013624:Taiwan / Q000453:epidemiology
chemical_list: D006514:Hepatitis B Surface Antigens; D011498:Protein Precursors