title: Use of microdissection and molecular genetics in the pathologic diagnosis of retinoblastoma.
abstract: OBJECTIVE
  Retinoblastoma results from mutations or loss of both alleles of the retinoblastoma gene. Although retinoblastoma is usually recognized clinically, some forms of the disease can elude diagnosis. The purpose of this study was to determine whether the use of molecular genetics to detect a loss of heterozygosity (LOH) in the retinoblastoma gene could assist the ocular pathologist in the diagnosis of this malignancy.
  
  
  METHODS
  Deoxyribonucleic acid (DNA) was obtained from tumor cells microdissected from three ocular specimens from two patients with diffuse retinoblastoma. Polymerase chain reaction was used to detect two microsatellite markers (D13S153 and D13S118) of the retinoblastoma gene. Loss of heterozygosity was identified when one of the two polymorphic alleles was present in the DNA from normal tissue but absent or reduced in the DNA obtained from tumor cells.
  
  
  RESULTS
  Loss of heterozygosity was identified in all three specimens from the two patients with diffuse retinoblastoma. In one patient, the diagnosis of retinoblastoma was based on identification of LOH from tumor cells obtained from vitrectomy.
  
  
  CONCLUSIONS
  This study demonstrates that identification of LOH in retinoblastoma cells not only can contribute to our understanding of the molecular genetics of this tumor, but also can help the ocular pathologist in the diagnosis of atypical forms of the disease.
authors.affiliation: National Eye Institute, National Institutes of Health, Bethesda, Maryland 20892-1858, USA. scottw@helix.nih.gov
authors.forename: S M
authors.initials: SM
authors.lastname: Whitcup
authors.forename: W S
authors.initials: WS
authors.lastname: Park
authors.forename: A T
authors.initials: AT
authors.lastname: Gasch
authors.forename: R C
authors.initials: RC
authors.lastname: Eagle
authors.forename: A C
authors.initials: AC
authors.lastname: Filie
authors.forename: R B
authors.initials: RB
authors.lastname: Nussenblatt
authors.forename: Z
authors.initials: Z
authors.lastname: Zhuang
authors.forename: C C
authors.initials: CC
authors.lastname: Chan
mesh_terms: D000293:Adolescent; D000483:Alleles; D002675:Child, Preschool; D004273:DNA, Neoplasm / Q000032:analysis*; D004210:Dissection / Q000379:methods; D005260:Female; D016161:Genes, Retinoblastoma / Q000235:genetics*; D006801:Humans; D019656:Loss of Heterozygosity / Q000235:genetics*; D018895:Microsatellite Repeats / Q000235:genetics; D017354:Point Mutation / Q000235:genetics; D016133:Polymerase Chain Reaction / Q000379:methods; D019572:Retinal Neoplasms / Q000175:diagnosis* / Q000235:genetics / Q000601:surgery; D012175:Retinoblastoma / Q000175:diagnosis* / Q000235:genetics / Q000601:surgery
chemical_list: D004273:DNA, Neoplasm