Detection of aneuploidy in human sperm by fluorescence in situ hybridization (FISH): different frequencies in fresh and stored sperm nuclei.

Fluorescence in situ hybridization (FISH) with chromosome-specific repetitive DNA probes provides a new method for rapid detection of aneuploidy in human sperm. There is widespread interest in this technique for basic research, as well as for screening men exposed to potential aneugens. A number of laboratories have reported a wide range in the frequency of aneuploidy for chromosomes in human sperm, suggesting that FISH may not reflect the true frequency accurately. We have serendipitously discovered that the length of time that fixed frozen sperm nuclei are stored affects both the hybridization efficiency and disomy frequency of individual chromosomes. This may explain some of the variation in the aneuploidy frequencies observed among laboratories.