Aneuploidy in human sperm: results of two-and three-color fluorescence in situ hybridization using centromeric probes for chromosomes 1, 12, 15, 18, X, and Y.

To understand the mechanisms that affect aneuploidy, fluorescence in situ hybridization (FISH), using chromosome-specific centromeric probes, was employed to screen a large population of human sperm for numerical errors. To determine the true rate of disomy for chromosomes 1, 12, 15, and 18, two-color FISH was performed, and for the gonosomes, three-color FISH. The use of multiple, differently colored probes allows one to distinguish a true disomic sperm from a diploid cell. A minimum of 10,000 sperm nuclei from each of five donors was scored per set of centromeric probes, giving a total of 165,330 sperm nuclei. The disomy frequencies for autosomes 1, 12, 15, and 18 were found to be similar, with a mean of 0.10% (range, 0.05%-0.16%) for chromosome 1, 0.16% (0.10%-0.25%) for chromosome 12, 0.11% (0.07%-0.20%) for chromosome 15, and 0.11% (0.08%-0.17%) for chromosome 18. For the sex chromosomes, the mean frequency of disomy was found to be 0.43% (range, 0.23%-0.71%), with XX disomy accounting for 0.07% (0.03%-0.10%), YY disomy 0.21% (0.10%-0.43%), and XY disomy 0.15% (0.08%-0.24%). The incidence of disomic sperm for the sex chromosomes was significantly increased, compared to the frequency of disomy for the autosomes (chi 2 = 218.61, P < 0.0001). Diploidy was observed in 0.05%-0.47% of the sperm nuclei counted. Interdonor heterogeneity for disomy frequencies was found to exist for the sex chromosomes and for chromosomes 1 and 15, suggesting significant variation among normal men.