Segregation of sex chromosomes in spermatozoa of 46,XY/47,XXY men by multicolour fluorescence in-situ hybridization.

The sex chromosome disomy and diploidy rates on ejaculated spermatozoa from two patients with mosaic Klinefelter's syndrome were estimated, using X/Y/15 multicolour fluorescence in-situ hybridization (FISH). A 8/18 dual fluorescence in-situ hybridization analysis was also carried out. In triple FISH, a total of 1691 (patient 1) and 811 (patient 2) spermatozoa were analysed. Frequencies of cells with hyperhaploidies for sex chromosomes were 2. 01% and 3.45% for patients 1 and 2 respectively, with both patients showing a significantly increased incidence of 24,XY and 24,XX disomies and only patient 2 showing a significantly increased incidence of 24,YY disomy in comparison to the control (P < 0.001). The 46,XX diploidy rate in patient 1 was also significantly higher than the control (P < 0.01). The ratio of X-bearing to Y-bearing spermatozoa differed from the expected 1:1 ratio for only patient 1 (1.18:1). There was no significant difference for chromosomes 8, 15 or 18 disomy frequencies in comparison to those estimated in the control population. These results support the hypothesis that some 47,XXY cells are able to go through meiosis and form spermatozoa with an abnormal gonosomal complement. Thus, there is an increased risk, for these 46,XY/47,XXY men, of producing offspring with a gonosomal abnormality.