title: Absence of IDH mutation in colorectal cancers with microsatellite instability.
abstract: BACKGROUND
  Colorectal cancers (CRCs) with deficient DNA mismatch repair system (dMMR) represents approximately 12% of all CRCs. Sporadic dMMR CRCs are due to hypermethylation MLH1 gene promoter and associated with the CpG island methylator phenotype (CIMP). Isocitrate dehydrogenase (IDH) mutant tumors are associated with DNA hypermethylation in various cancers.
  
  
  OBJECTIVE
  Look if dMMR CRC are associated with IDH mutations.
  
  
  METHODS
  All consecutive dMMR CRCs between 2005 and 2014 were included in this study. Tumoral DNA used for dMMR analysis was also used to determine IDH1 and IDH2 mutations using pyrosequencing method.
  
  
  RESULTS
  A total of 152 dMMR CRCs patients were analyzed. No IDH mutation was observed in dMMR CRC, nor in IDH1 or IDH2. Especially, no mutation was found in sporadic dMMR CRC which is known to be associated with CIMP.
  
  
  CONCLUSIONS
  In contrast with others types of hypermethylated tumors, dMMR CRCs are not associated with IDH mutations.
authors.affiliation: EA 4331/LITEC, Laboratoire Inflammation, Tissus Epithéliaux et Cytokines Poitiers, Poitiers University, France; Gastroenterology Department, Poitiers University Hospital, Poitiers, France. Electronic address: davidtougeron@hotmail.fr.
authors.forename: David
authors.initials: D
authors.lastname: Tougeron
authors.affiliation: Cancer Biology Department, Poitiers University Hospital, Poitiers, France.
authors.forename: Karline
authors.initials: K
authors.lastname: Guilloteau
authors.affiliation: Cancer Biology Department, Poitiers University Hospital, Poitiers, France; INSERM U1084/LNEC, Poitiers University, Poitiers, France.
authors.forename: Lucie
authors.initials: L
authors.lastname: Karayan-Tapon
mesh_terms: D000368:Aged; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000473:pathology; D019175:DNA Methylation; D053843:DNA Mismatch Repair; D005260:Female; D005602:France; D006801:Humans; D007521:Isocitrate Dehydrogenase / Q000235:genetics*; D008297:Male; D053842:Microsatellite Instability; D008875:Middle Aged; D009154:Mutation
chemical_list: C538784:IDH2 protein, human; D007521:Isocitrate Dehydrogenase; C543588:IDH1 protein, human
keywords: Colon cancer; Deficient DNA mismatch repair; Isocitrate dehydrogenase