title: Correlation of the presence and extent of loss of heterozygosity mutations with histological classifications of Barrett's esophagus.
abstract: BACKGROUND
  Recent advances in the management of Barrett's Esophagus (BE) have placed greater emphasis on accurate diagnosis of BE as well as better prediction of risk for progression to esophageal adenocarcinoma (EAC). Histological evaluation of BE is particularly challenging with significant inter-observer variability. We explored the presence and extent of genomic instability in BE biopsy specimens as a means to add supplementary information to the histological classification and clinical decision-making related to early disease.
  
  
  METHODS
  We reviewed histology slides from 271 patients known to have BE. Using histological features as a guide, we microdissected target cell populations with various histological classifications of BE (intestinal metaplasia, "indefinite for dysplasia", low grade dysplasia, or high grade dysplasia). DNA was extracted from microdissected targets and analyzed for loss of heterozygosity (LOH) using a panel of 16 LOH mutational markers associated with tumor suppressor genes at chromosomal loci 1p, 3p, 5q, 9p, 10q, 17p, 17q, 18q, 21q, 22q. The presence or absence of mutations and the clonality of each mutation were determined for each marker.
  
  
  RESULTS
  The presence and clonal expansion of LOH mutations was formulated into mutational load (ML) for each microdissected target analyzed. ML correlated with the histological classification of microdissected targets, with increasingly severe histology having higher ML. Three levels of mutation load (no ML, low ML, and high ML) were defined based on the population of microdissected targets histologically classified as intestinal metaplasia. All microdissected targets with dysplasia had mutations, with a high ML consistently present in high grade dysplasia targets. Microdissected targets histologically classified as intestinal metaplasia or "indefinite for dysplasia" spanned a range of no, low, and high ML.
  
  
  CONCLUSIONS
  The results of this study reinforce the association of genomic instability with disease progression in BE. The presence and extent (clonality) of genomic instability, as assessed by mutational load, may assist histology in defining early stages of BE that are potentially at greater risk for disease progression. Assessment of mutational load using our panel of LOH mutational markers may be a useful adjunct to microscopic inspection of biopsy specimens, and thereby, improve patient management.
authors.affiliation: RedPath Integrated Pathology, Inc, 2515 Liberty Ave, Pittsburgh, PA 15222, USA.
authors.forename: Eric
authors.initials: E
authors.lastname: Ellsworth
authors.forename: Sara A
authors.initials: SA
authors.lastname: Jackson
authors.forename: Shyam J
authors.initials: SJ
authors.lastname: Thakkar
authors.forename: Dennis M
authors.initials: DM
authors.lastname: Smith
authors.forename: Sydney
authors.initials: S
authors.lastname: Finkelstein
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001471:Barrett Esophagus / Q000235:genetics* / Q000473:pathology*; D004252:DNA Mutational Analysis; D018450:Disease Progression; D005260:Female; D016147:Genes, Tumor Suppressor; D042822:Genomic Instability; D006801:Humans; D019656:Loss of Heterozygosity; D008297:Male; D008679:Metaplasia / Q000235:genetics; D008875:Middle Aged; D025803:Tumor Suppressor Protein p14ARF / Q000235:genetics; D016159:Tumor Suppressor Protein p53 / Q000235:genetics
chemical_list: D025803:Tumor Suppressor Protein p14ARF; D016159:Tumor Suppressor Protein p53