Chromosomal aberrations are an important cause of spontaneous abortions. In order to detect numerical aberrations, paraffin-embedded tissue from 26 abortions with known conventional cytogenetic findings (CCG;25 numerical aberrations and one partial trisomy 7p) was analyzed by means of interphase cytogenetics (ICG) using centromer-specific DNA probes for chromosomes X, Y, 10, 18, and 13/21. Limit-values for the diagnosis of aneusomy in tissue sections were established by classifying the distribution of hybridization signals by CCG data (for gain ≤15% of nuclei with +1 signal; for deletion >40% of nuclei with -1 signal). Signal distribution in tissue sections and nuclear suspensions from paraffin blocks analyzed in parallel showed statistically a highly significant correlation (P<0.0001). ICG and CCG diagnoses corresponded in 18 of 20 cases suitable for evaluation (90%; no false-positive result). No correlation between cytogenetic and histologic findings could be found. ICG proved to be a reliable tool for the detection of numerical chromosomal aberrations in paraffin-embedded tissue of abortions (sections and nuclear supensions). Thus, data for genetic counselling of the parents can be provided. The limit values for diagnosis of aneusomy could also be important for the application of ICG in tumor cytogenetics.
