Segregation of sex chromosomes into sperm nuclei in a man with 47,XXY Klinefelter’s karyotype: a FISH analysis

Abstract

Meiotic segregation of the sex chromosomes was analysed in sperm nuclei from a man with Klinefelter’s karyotype by three-colour FISH. The X- and Y-specific DNA probes were co-hybridized with a probe specific for chromosome 1, thus allowing diploid and hyperhaploid spermatozoa to be distinguished. A total of 2206 sperm nuclei was examined; 958 cells contained an X chromosome, 1077 a Y chromosome. The ratio of X : Y bearing sperm differed significantly from the expected 1 : 1 ratio (χ² = 6.96; 0.001 < P < 0.01). Sex-chromosomal hyperhaploidy was detected in 2.67% of the cells (1.22% XX, 1.36% XY, 0.09% YY) and a diploid constitution in 0.23%. Although the frequency of 24,YY sperm was similar to that detected in fertile males, the frequencies of 24,XX, 24,XY and diploid cells were significantly increased. A sex-chromosomal signal was missing in 4.26% of the spermatozoa. This percentage appeared to be too high to be attributed merely to nullisomy for the sex chromosomes and was considered, at least partially, to be the result of superposition of sex-chromosomal hybridization signals by autosomal signals in a number of sperm nuclei. The results contribute additional evidence that 47,XXY cells are able to complete meiosis and produce mature sperm nuclei.