Toward quality assurance for metaphase FISH: A multicenter experience

Gordon W. Dewald, Richard Stallard, Patricia I. Bader, Kathy Chen, Julie Zenger-Hain, Catherine J. Harris, Rodney Higgins, Betsy Hirsch, Wei Tong Hsu, Eric Johnson, Virginia Kubic, T. W. Kurczynski, James M. Malone, D. James McCorquodale, Karen Meilinger, Lorraine F. Meisner, J. W. Moore, Stuart Schwartz, Steven Siembieda, Patrick D. StortoGail Vance, Peter Van Tuinen, Ann Wiktor, Jar Fee Yung

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


Although fluorescent in situ hybridization (FISH) is rapidly becoming a part of clinical cytogenetics, no organization sponsors multicenter determinations of the efficacy of probes. We report on 23 laboratories that volunteered to provide slides and to use a probe for small nuclear ribonucleoprotein polypeptide N (SNRPN) and a control locus. Experiences with FISH for these laboratories during 1994 ranged from 0 to 645 utilizations (median = 84) involving blood, amniotic fluid, and bone marrow. In an initial study of hybridization efficiency, the median percentage of metaphases from normal individuals showing two SNRPN and two control signals for slides prepared at each site was 97.0 (range = 74-100); for slides prepared by a central laboratory, it was 97.8 (range = 81.6-100). In a subsequent blind study, each laboratory attempted to score 5 metaphases from each of 23 specimens [8 with del(15)(q11.2→q12) and 15 with normal 15 chromosomes]. Of 529 challenges, the correct SNRPN pattern was found in 5 of 5 metaphases in 457 (86%) and in 4 of 5 in 33 (6%). Ambiguous, incomplete, or no results were reported for 32 (6%) challenges. Seven (1%) diagnostic errors were made, including 6 false positives and 1 false negative: 1 laboratory made 3 errors, 1 made 2, and 2 made 1 each. Most errors and inconsistencies seemed due to inexperience with FISH. The working time to process and analyze slides singly averaged 49.5 min; slides processed in batches of 4 and analyzed singly required 36.9 min. We conclude that proficiency testing for FISH by using an extensive array of challenges is possible and that multiple centers can collaborate to test probes and to evaluate costs.

Original languageEnglish (US)
Pages (from-to)190-196
Number of pages7
JournalAmerican Journal of Medical Genetics
Issue number3
StatePublished - Oct 28 1996


  • Prader-Willi syndrome
  • SNRPN probe
  • hybridization efficiency
  • metaphase FISH
  • mosaicism
  • proficiency testing
  • quality assurance
  • workload


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