Comparison of DNA fragmentation levels in spermatozoa with different sex chromosome complements

Research question: Do spermatozoa with different sex chromosome complements (X and Y; aneuploidy and monosomy) exhibit different degrees of DNA damage?

Design: A prospective, observational study to measure the DNA fragmentation level and sex chromosome complement simultaneously using combined sperm chromosome dispersion (SCD) and fluorescence in-situ hybridization tests. Two methods were used to evaluate SCD images: a traditional semi-quantitative method to categorize halo size and a newly developed quantitative method based on the Matlab image analysis programme to more precisely measure the halo area and calculate the halo size index (HSI).

Results: The HSI (which was inversely proportional to DNA fragmentation level) of Y chromosome-bearing spermatozoa was significantly (P < 0.05) lower than that of X chromosome-bearing spermatozoa in both normozoospermic and pathozoospermic groups. The HSI of sex chromosome-aneuploid spermatozoa was also significantly (P < 0.05) lower than that of monosomic spermatozoa.

Conclusions: Our results indicated that Y chromosome-bearing spermatozoa are more susceptible to DNA damage than X chromosome-bearing spermatozoa, and the segregation errors during the meiotic division of spermatogenesis (resulting in aneuploidy) constitute an important contributory cause of DNA damage.