title: Tissue specific somatic mutations and aganglionosis in Hirschsprung's disease.
abstract: BACKGROUND
  RET proto-oncogene intron 1 variations [e.g. SNP1 (rs2506004) and SNP2 (rs 2435357)] have been shown to be etiologically important in the pathogenesis of Hirschsprung's disease (HSCR). Although activating somatic RET rearrangements have been identified in certain tumours, this is the first study to confirm somatic gene variation in HSCR.
  
  
  METHODS
  DNA was extracted from 53 paraffin embedded tissue samples (HSCR patients n=33, multiple levels n=17), and controls (n=3). Patients were grouped into aganglionic (Group 1), ganglionated (group 2), and transitional (group 3). PCR products of RET intron 1 were screened for genetic variation by semi-automated bi-directional sequencing analysis and matched to unaffected controls from the general population. Comparison was by Fishers exact test. P <0.05 was regarded as significant.
  
  
  RESULTS
  HSCR patients included short segment (n=26), long segment colonic [(n=4 (24%)], and total colonic aganglionosis (n=3). RET intronic variations [SNP1 (rs2506004) or SNP2 (rs 2435357)] showed somatic homozygous in affected tissue in 9/12 (75%) Group 1 (aganglionic tissue) compared with 2/5 (40%) and 1/10 (10%) of groups 2 and 3 (P<0.001). Homozygous SNP2 variation was observed in all long segment versus 4/10 short segment. 50% of the short segment cases showing homozygous SNP 1 variation.
  
  
  CONCLUSIONS
  We report somatic mutations in the RET intron 1 region of affected HSCR tissue, confirming for the first time that somatic mutations are present in aganglionic tissue and may promote local aganglionosis through deregulated receptor activity. Detailed understanding of the somatic genetic events that drive congenital aganglionosis may have bearing on diagnosis and therapy.
authors: Division of Pediatric Surgery, Department of Surgical Sciences, Faculty of Health Sciences, University of Stellenbosch, Tygerberg, South Africa. Electronic address: swm@sun.ac.za.
authors: Sam W
authors: SW
authors: Moore
authors: Division of Pediatric Surgery, Department of Surgical Sciences, Faculty of Health Sciences, University of Stellenbosch, Tygerberg, South Africa.
authors: Monique G
authors: MG
authors: Zaahl
mesh_terms: D002648:Child; D014644:Genetic Variation; D018095:Germ-Line Mutation; D006627:Hirschsprung Disease / Q000235:genetics*; D006801:Humans; D007438:Introns; D016133:Polymerase Chain Reaction; D020641:Polymorphism, Single Nucleotide; D000090063:Proto-Oncogene Mas; D051096:Proto-Oncogene Proteins c-ret
chemical_list: C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D051096:Proto-Oncogene Proteins c-ret
keywords: Genetics; Hirschsprung's disease; RET proto-oncogene; Somatic mutation