title: Distribution and clinical significance of hepatitis B virus genotypes in Pakistan.
abstract: BACKGROUND
  Hepatitis B virus (HBV) genotype and its role in disease progression and patients' response to antiviral treatment, is not well studied in Pakistan. This comprehensive study was aimed to determine the distribution of HBV genotypes in Pakistan and their possible association with phases of HBV infection.
  
  
  METHODS
  A total of 840 HBsAg positive samples was collected and tested for HBV DNA quantity. Samples below 100 IU/ml were excluded from the study. A total of 715 samples representing all the six parts of the country were genotyped by type specific primer PCR method. Clinical data of only 384 patients was compared as the remaining 332 were either receiving antiviral treatment or their infection phase was not confirmed.
  
  
  RESULTS
  Genotype D was found in 509 samples (71.2 %), genotype A in 55 samples (7.7 %) and mixed infection with genotypes A and D in 124 samples (17.3 %). Genotypes B, C and E were identified in less than 1 % of the total samples. Genotype A, D and their mixture (A + D) were compared for severity of HBV infection. Significant differences were not found in distribution of HBV genotypes among different disease stages.
  
  
  CONCLUSIONS
  HBV genotype D was the predominant infection in all study areas of Pakistan followed by mixed genotypes infection (A + D) whereas genotype A has 10 times lower prevalence than genotype D. Genotypes B, C, E and F altogether make only 1.5 % of the prevalence. Genotype do not appears to show the severity of liver disease.
authors: Department of Zoology, The University of Poonch, Rawalakot, Azad Jammu and Kashmir, 12350, Pakistan. majid1133@gmail.com.|Department of Zoology, Pir Mehr Ali Shah Arid Agriculture University, Rawalpindi, 46300, Pakistan. majid1133@gmail.com.
authors: Majid
authors: http://orcid.org/0000-0001-6680-3541
authors: M
authors: Mahmood
authors: Department of General Medicine, Pakistan Atomic Energy Commission (PAEC) General Hospital, Islamabad, 44000, Pakistan.
authors: Muhammad Asim
authors: MA
authors: Anwar
authors: Barani Institute of Management Sciences (BIMS), Rawalpindi, 46300, Pakistan.
authors: Azra
authors: A
authors: Khanum
authors: Center for Biotechnology & Microbiology, University of Swat, Swat, 19130, Pakistan.
authors: Nasib
authors: N
authors: Zaman
authors: Diagnostic Department, Nuclear Medicine, Oncology and Radiotherapy Institute (NORI), Islamabad, 44000, Pakistan.
authors: Abida
authors: A
authors: Raza
mesh_terms: D000328:Adult; D000998:Antiviral Agents / Q000627:therapeutic use; D060085:Coinfection / Q000453:epidemiology / Q000821:virology; D004279:DNA, Viral / Q000097:blood*; D005260:Female; D005838:Genotype; D006514:Hepatitis B Surface Antigens / Q000097:blood; D006515:Hepatitis B virus / Q000235:genetics*; D019694:Hepatitis B, Chronic / Q000097:blood* / Q000188:drug therapy / Q000821:virology; D006801:Humans; D008297:Male; D010154:Pakistan / Q000453:epidemiology; D016133:Polymerase Chain Reaction / Q000379:methods; D015995:Prevalence
chemical_list: D000998:Antiviral Agents; D004279:DNA, Viral; D006514:Hepatitis B Surface Antigens
keywords: HBV genotypes; Hepatitis B virus; Liver disease progression; PCR