A MULTICENTER INVESTIGATION WITH INTERPHASE FLUORESCENCE IN-SITU HYBRIDIZATION USING X-CHROMOSOME AND Y-CHROMOSOME PROBES

Twenty-six laboratories used X and Y chromosome probes and the same pr ocedures to process and examine 15,600 metaphases and 49,400 interphas es from Phaseolus vulgaris-eucoagglutinin (PHA)-stimulated lymphocytes . In Part I, each laboratory scored 50 metaphases and 200 interphases from a normal male and a normal female from its own practice. In Part II, each laboratory scored 50 metaphases and 200 interphases on slides prepared by a central laboratory from a normal male and a normal fema le and three mixtures of cells from the male and female. In Part III, each laboratory scored 50 metaphases (in samples of 5, 10, 15, and 20) and 100 interphases (in samples of 5, 10, 15, 20, and 50) on new, cod ed slides of the same specimens used in Part Il. Metaphases from male specimens were scored as 98-99% XY with no XX cells, and 97-98% of int erphases mere scored as XY with 0.04% XX cells. Metaphases from female specimens were scored as 96-97% XX with 0.03% XY cells, and 94-96% of interphases were scored as XX with 0.05% XY cells. Considering the da ta as a model for any probe used with fluorescence in situ hybridizati on (FISH), a statistical approach assessing the impact of analytical s ensitivity on the numbers of observations required to assay for potent ial mosaicisms and chimerisms is discussed. The workload associated wi th processing slides and scoring 50 metaphases and 200 interphases usi ng FISH averaged 27.1 and 28.6 minutes, respectively. This study indic ates that multiple laboratories can test/develop guidelines for the ra pid, efficacious, and cost-effective integration of FISH into clinical service. (C) 1998 Wiley-Liss, Inc.