Detection of aneuploidy in human spermatozoa using fluorescence in situ hybridization (FISH)

Comprehensive chromosome FISH assessment of sperm aneuploidy in normozoospermic males

PURPOSE

Sperm chromosomal abnormalities impact male fertility and pregnancy outcomes. However, the proportion of sperm with chromosomal abnormalities in normozoospermic men remains unclear. Herein, we evaluated sperm aneuploidy for 23 chromosomes to elucidate its incidence in normozoospermic men.

METHODS

Sperm from ten normozoospermic donors were obtained from a human sperm bank and analyzed using fluorescence in situ hybridization. The frequencies of nullisomy, disomy, and diploidy were analyzed along with trisomy, triploidy, tetraploidy, and other numerical abnormalities per chromosome and per donor levels.

RESULTS

A total of 248,811 sperm cells were analyzed (average: 24,881 ± 381 cells/donor), of which 246, 658 were haploid, 818 nullisomic, 393 disomic, 894 diploid, 13 triploid, 8 tetraploid, 3 trisomic, and 24 harbored multiple aneuploidies. Among the 22 autosomal and 2 sex chromosomes, the mean frequency of aneuploidy per chromosome was 0.49 ± 0.16%, including 0.33 ± 0.16% for nullisomy and 0.16 ± 0.08% for disomy. The mean frequencies of nullisomy, disomy, and aneuploidy per donor were 0.33 ± 0.13%, 0.16 ± 0.05%, and 0.49 ± 0.13%, respectively. The total frequencies of nullisomy, disomy, diploidy, and aneuploidy per donor were 7.62 ± 3.06%, 3.63 ± 1.12%, 0.36 ± 0.15%, and 11.25 ± 3.05%, respectively.

CONCLUSIONS

The dominant chromosome numerical abnormalities in normozoospermic men are nullisomy, disomy, and diploidy. Generally, the frequency of nullisomy is higher than that of disomy. The disomy or nullisomy frequencies for each chromosome being gained or lost were not unified and varied; some chromosomes (e.g., chromosomes 21 and 22 and sex chromosomes) are more prone to disomy while some others (e.g., chromosome 3) are more prone to nullisomy.

The association between male infertility and sperm disomy: evidence for variation in disomy levels among individuals and a correlation between particular semen parameters and disomy of specific chromosome pairs

Background

The association between infertility and sperm disomy is well documented. Results vary but most report that men with severely compromised semen parameters have a significantly elevated proportion of disomic sperm. The relationship between individual semen parameters and segregation of specific chromosome pairs is however less well reported as is the variation of disomy levels in individual men.

Methods

In order to address these questions the technique of fluorescent in-situ hybridisation (FISH) was utilised to determine the disomy levels of chromosomes X, Y and 21 in 43 sperm samples from 19 infertile males. The results generated from this study were analysed using logistic regression.

Results

In this study we compared levels of sperm concentration, motility and morphology with levels of sperm disomy for chromosome 21 and the sex chromosomes. Our results suggest that there is considerable variation in disomy levels for certain men. They also suggest that oligozoospermic males have significantly elevated levels of sex chromosome disomy but not disomy 21; they suggest that severe asthenozoospermic males have significantly elevated levels of disomy 21 but not sex chromosome disomy. Surprisingly, severe teratozoopsermic males appeared to have significantly lower levels of sperm disomy for both the sex chromosomes and chromosome 21.

Conclusion

We suggest that the association between sex chromosome disomy and oligozoospermia may be due to reduced recombination in the XY pairing region and discuss the relevance of our findings for the correlations between sperm disomy and sperm motility and morphology.