Incidence of chromosome 21 disomy in human spermatozoa as determined by fluorescent in-situ hybridization

We have evaluated the incidence of chromosome 21 disomy in decondensedsperm heads from nine normal men using a locus-specific DNAprobe for chromosome 21, and a centromeric probe for chromosome6 as a control. The results show that the incidence of chromosome21 disomy (0.38%) is significantly higher than disomy for chromosome6 (0.14%). No differences were found among the individuals analysed.