FLUORESCENCE IN-SITU HYBRIDIZATION ON PARAFFIN-EMBEDDED ABORTION MATERIAL AS A MEANS OF RETROSPECTIVE CHROMOSOME ANALYSIS

A fluorescence in situ hybridization (FISH) procedure was used to dete ct chromosome abnormalities in archival abortion material. Nuclei were isolated from 50-mu m-thick tissue blocks from 18 selected and karyot yped abortions. Five probes for repetitive centromeric sequences of ch romosomes 1, 16, 18, X and Y were used. For each chromosome, at least 200 nuclei were scored blindly, i.e. without knowledge of the karyotyp e. The FISH results obtained were compatible with the cytogenetic data in 14 cases. There were four discrepancies. Two of these were observe d for cases karyotyped as trisomy 16. Furthermore, FISH results showed trisomy 18 in two cases having normal chromosomes 18 and 18q+, respec tively. The latter case was not discrepant if the structural rearrange ment involved chromosome 18 material. The remaining discrepancies coul d be explained by chromosomal mosaicism. Admixture of normal maternal cells was also noted. It is concluded that FISH can be used to study r etrospectively the presence of chromosome abnormalities in abortion ma terial. However, the quality obtained after the use of fresh material is superior.