title: Genetic alterations on chromosome 19, 20, 21, 22, and X detected by loss of heterozygosity analysis in retinoblastoma.
abstract: OBJECTIVE
  To explore the presence of common genetic alterations in retinoblastoma and to localize the altered genomic regions.
  
  
  METHODS
  Genetic analysis included determinations of the loss of heterozygosity (LOH) and microsatellite instability (MSI) on chromosomes 19, 20, 21, 22, and X. Investigations were carried out among 15 microdissected retinoblastoma tumors and corresponding genomic DNA specimens.
  
  
  RESULTS
  Among the 15 retinoblastoma cases, 73% (11/15) showed genome instability (LOH and/or MSI) at one or more loci on the 5 chromosomes, although loci with recurrent LOH was infrequent. The loss of a single allele was more frequent in chromosomes 19 (33%) and 20 (27%) than the other 3 chromosomes. Five loci with recurrent allelic loss were identified, among them the most frequent allelic losses were between D19S902 and D19S571 on 19q13 and were identified in 3 out of the 15 tumor specimens. The results suggested that gene loci in the 19q13 region may be associated with tumor development in retina. In addition, 3 specimens showed moderate frequency of LOH and/or MSI in more than 6 microsatellite markers, indicating genomic instability to occur at least in a subset of retinoblastoma.
  
  
  CONCLUSIONS
  Our results provide the first evidence of LOH in chromosomes 19 and 20 in retinoblastoma. They also support the proposition that presence of genome instability in retinoblastoma may play a role in the tumorigenesis or progression of retinoblastoma.
authors.affiliation: Department of Ophthalmology Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China.
authors.forename: Qing
authors.initials: Q
authors.lastname: Huang
authors.forename: Kwong Wai
authors.initials: KW
authors.lastname: Choy
authors.forename: Kin Fai
authors.initials: KF
authors.lastname: Cheung
authors.forename: D S C
authors.initials: DS
authors.lastname: Lam
authors.forename: Wei Ling
authors.initials: WL
authors.lastname: Fu
authors.forename: Chi Pui
authors.initials: CP
authors.lastname: Pang
mesh_terms: D002675:Child, Preschool; D002877:Chromosomes, Human / Q000235:genetics*; D002888:Chromosomes, Human, Pair 19 / Q000235:genetics; D002890:Chromosomes, Human, Pair 20 / Q000235:genetics; D002891:Chromosomes, Human, Pair 21 / Q000235:genetics; D002892:Chromosomes, Human, Pair 22 / Q000235:genetics; D041321:Chromosomes, Human, X / Q000235:genetics; D004273:DNA, Neoplasm / Q000235:genetics; D005260:Female; D006801:Humans; D007223:Infant; D019656:Loss of Heterozygosity; D008297:Male; D018895:Microsatellite Repeats / Q000235:genetics; D019572:Retinal Neoplasms / Q000235:genetics*; D012175:Retinoblastoma / Q000235:genetics*
chemical_list: D004273:DNA, Neoplasm