Multicolor Fluorescence in Situ Hybridization Analysis of Aneuploidy and Diploidy Frequencies in 225 846 Sperm from 10 Normal Men1

Aneuploidy and diploidy frequencies for chromosomes 1, 12, X, and Y were assessed in 225,846 sperm from 10 normal men. Results from 5 of the men have previously been reported. Multicolor fluorescence in situ hybridization (FISH) was used to control for lack of probe hybridization and to distinguish diploidy from disomy. A minimum of 10,000 sperm per donor were evaluated for each chromosome. Sperm were considered disomic if two fluorescent signals were separated by a distance of a minimum of one signal domain. The mean frequencies of disomic sperm for chromosomes 1 and 12 were 0.11% (range 0.05-0.18%) and 0.16% (range 0.10-0.25%), respectively. The means for the sex chromosomal aneuploidies were 0.07% XX, 0.18% YY, and 0.16% XY, totaling 0.42% for all sex chromosomes (range 0.23-0.71%). The incidence of disomic sperm for the sex chromosomes was significantly increased compared to the frequency for the autosomes, corroborating results obtained from studies of sperm karyotypes and spontaneous abortions. The mean frequencies of single X- and Y-bearing sperm were 50.1% and 49.0%, respectively--not significantly different from 50%. The mean frequency of diploid sperm was 0.16% (0.06-0.42%). Interdonor heterogeneity was found to exist for disomy 1, XX, YY, and diploidy, suggesting significant variation among normal men. Comparison of these FISH results to our historical sperm karyotypes demonstrated that the sex ratios and disomy frequencies for chromosomes 1 and X were similar. However, there was a significantly increased frequency of disomic sperm for chromosomes 12, YY, and XY in FISH data compared with sperm karyotypes. In general, FISH data agreed quite well with values from sperm karyotyping, including the increased frequency of sex chromosomal aneuploidy compared with autosomal aneuploidy in sperm. Multicolor FISH analysis permits an accurate distinction between disomic and diploid sperm and allows analysis of large sample sizes. This powerful technology may be useful for future studies of potential environmental and occupational mutagens.