title: Point mutation of K-ras gene codon 12 in biliary tract tumors.
abstract: OBJECTIVE
  Point mutations of the K-ras gene have been reported in a wide variety of human tumors. However, there might be conflicting data about its presence or incidence in biliary tract tumors. The aim of this study is to elucidate the presence and types of point mutation in biliary tract tumors, including gallbladder carcinoma and adenoma, extrahepatic bile duct carcinoma, and ampullary carcinoma.
  
  
  METHODS
  Mutation bands detected in modified two-step polymerase chain reaction were eluted from agarose gel and analyzed by dideoxy sequencing method.
  
  
  RESULTS
  Of 20 biliary tract tumors showing a mutation band, G to A single base substitutions were confirmed in 15 cases as the most frequent changes, which were divided into changes for aspartic acid (GAT) and (14) serine (AGT) (1). Changes for valine (GTT) were found in two cases. In extrahepatic bile duct carcinoma, duplicate mutations (GA/TT) were found in two cases and triplicate mutation (A/GA/TT) in one case. The adenoma portion of one "cancer in adenoma" case of gallbladder showed the single base transition (GAT) in the second position, same as in the carcinoma portion.
  
  
  CONCLUSIONS
  Most of the biliary tract tumors comprised point mutation in K-ras gene codon 12, and G to A transition was the most frequent.
authors.affiliation: Third Department of Internal Medicine, Hokkaido University School of Medicine, Sapporo, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Watanabe
authors.forename: M
authors.initials: M
authors.lastname: Asaka
authors.forename: J
authors.initials: J
authors.lastname: Tanaka
authors.forename: M
authors.initials: M
authors.lastname: Kurosawa
authors.forename: M
authors.initials: M
authors.lastname: Kasai
authors.forename: T
authors.initials: T
authors.lastname: Miyazaki
mesh_terms: D000236:Adenoma / Q000473:pathology; D018195:Adenosarcoma / Q000473:pathology; D000368:Aged; D000369:Aged, 80 and over; D001483:Base Sequence; D001661:Biliary Tract Neoplasms / Q000235:genetics*; D003062:Codon; D005260:Female; D011905:Genes, ras; D006801:Humans; D008297:Male; D008875:Middle Aged; D015335:Molecular Probes / Q000235:genetics; D008969:Molecular Sequence Data; D009378:Neoplasms, Multiple Primary / Q000473:pathology; D017354:Point Mutation
chemical_list: D003062:Codon; D015335:Molecular Probes