[Numerical chromosome anomalies in human sperm at low sperm concentration]

With the assisted reproduction techniques the natural selection of sperm is bypassed on different levels.

The aim of the present work is to determine the frequencies of sperm numerical chromosome aberrations in infertile men with low sperm count and to examine the relationship between the spermatogram parameters (sperm count and motility) and the aneuploidy and diploidy frequencies.

32 men with low sperm count were investigated. Semen analysis was performed according to the WHO criteria. Disomy and diploidy frequencies were detected with fluorescence in situ hibridization using 17, X and Y centromeric probes. 200,969 sperm were scored, with the mean of 6272 cells in each subjects. The rate of numerical chromosome anomalies were also estimated using the detected disomy and the diploidy frequencies.

Mean sperm concentration of the 32 men was 18.2 million/ml (SD: +/- 8.43, range: 8.0-45.5), mean motility 49.4% (+/- 9.32, 30-69.2). The X/Y ratio was 1.07. The mean frequencies of sex chromosome disomy, chromosome 17 disomy and diploidy were 0.36%, 0.16% and 0.56%, respectively. The most frequent disomy was XY disomy (0.14). Sex chromosome disomy frequencies were higher in oligospermic samples (0.37% vs. 0.32%, OR = 1.18, 95% CI = 1.01-1.39, p < 0.001). With special regard to XY disomy (0.08% vs. 0.17%, OR = 1.99, 95% CI = 1.48-2.67, p < 0.001). In subjects with oligoasthenozoospermia the diploidy frequency increased (0.96%, OR = 2.39, 95% CI = 2.13-2.69, p < 0.001), mostly due to the elevated rate of diploid sperm of meiosis II. origin (XX or YY diploids). Estimated frequency of the numerical chromosome anomalies was 8.3 +/- 5.3 in the study population. Neither the sperm count, nor the sperm motility showed correlation with the detected frequency of the chromosome aberrations.

In oligospermic patients there is a risk for elevated frequency of sperm with sex chromosome aneuploidy, especially the XY disomy. Furthermore, the diploidy frequency is increased in oligozooastenospermic samples. Nevertheless, classical parameters of semen analysis (sperm count and motility) do not correlate with the frequency of numerical chromosomal anomalies. The risk can be determined using fluorescens in situ hybridization on sperm.