Sex chromosome ratios determined by karyotypic analysis in albumin-isolated human sperm.

Human sperm that had been processed for Y-enrichment (male sex preselection) according to a currently favored albumin density gradient procedure were analyzed karyotypically for the proportion of X and Y chromosomes with the use of the human sperm/hamster egg system. This method allows direct inspection of haploid chromosome complements from human sperm. In 290 albumin-isolated sperm from six men, there were 57.2% X- and 42.8% Y-bearing chromosome complements; 201 unprocessed concurrent control sperm from five of the men had 50.2% X and 49.8% Y complements. The observed shift in sex chromosome ratio in processed samples, a decrease in Y-bearing sperm, was not statistically different from that of unprocessed controls (P = 0.13) but was significantly different when compared with the theoretic X/Y ratio of 50/50 (P = 0.016). A total of 3187 historical control karyotypes were also reviewed, with an overall sex chromosome ratio (X/Y) of 49.8/50.2. The control groups did not differ significantly from the expected 50/50. The Y-enrichment of processed sperm was not confirmed.