Differential sperm DNA fragmentation of X- and Y chromosome bearing human spermatozoa
Refereed conference paper presented and published in conference proceedings

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AbstractStudy question: Do X- and Y- chromosome bearing spermatozoa have different levels of DNA fragmentation?Summary answer: Sperm DNA fragmentation level of Y- chromosome bearing spermatozoa was significantly higher than X- chromosome bearing spermatozoa in pathozoospermic subjects, but not in normozoospermic subjects.
What is known already: Sperm DNA fragmentation could be induced by suboptimal testicular and epididymis environment. The Y chromosome of sperm has been considered particularly vulnerable to DNA damage, partly because of its genetic structure and partly because it cannot correct doublestranded DNA fragments by homologous recombination. An early mice study demonstrated that X- chromosome bearing spermatozoa are more robust to irradiation induced DNA damage than Y- chromosome bearing spermatozoa. However, direct evidence is lacking regarding whether X- and Y- chromosome bearing sperm has different susceptibilities to DNA fragmentation.
Study design, size, duration: This is a cross sectional study, which included 100 men who underwent routine fertility assessment between November 2015 and June 2016.
Participants/materials, setting, methods: Fifty normozoospermic men (Group I) and fifty pathozoospermic men (Group II) were recruited in this study. All participants received routine semen analysis at the IVF unit of Prince of Wales Hospital, the Chinese University of Hong Kong. DNA fragmentation states and sex chromosome complement were assessed by a combined test of sperm chromatin dispersion (SCD) and fluorescence in situ hybridization (FISH), followed by an observation of at least 300 spermatozoa/sample under florescent microscope.
Main results and the role of chance: We found, for the first time, in our study that the median level of DNA fragmentation in Y- chromosome bearing spermatozoa was significantly (P < 0.05) higher than that of X- chromosome bearing spermatozoa when all subjects were considered together (23.5% and 20.4% respectively) or in Group II (25.9% and 22.5% respectively), but not (P>0.05) in Group I (17.2% and 17.3% respectively). We also observed several findings which were in line with previous studies: (1) DNA fragmentation level is correlated with both sperm concentration [regression coefficient (RC) 95% confidence interval (CI): 0.08 (0.01 to -0.15); P = 0.03] and motility (RC (95% CI): -0.33 (-0.48 to -0.17); P < 0.001); (2) DFI and sex chromosome disomic rate of subjects in the pathozoospermic group [median(IQR): 4.81%(2.73%-8.98%)] was significantly higher (P = 0.01) than subjects in the normozoospermic group [median(IQR): 2.40%(1.79-4.78%)].
Limitations, reasons for caution: We did not assess the autosomes complement of spermatozoa in our study. As a result, we cannot determine the impact of autosomes aneuploidy on sperm DNA fragmentation.
Wider implications of the findings: Y- chromosome bearing spermatozoa
are more susceptible to DNA damage under suboptimal testicular environment, especially in pathozoospermic subjects. The clinical relevance of the finding requires further investigation.
Trial registration number: N/A.
All Author(s) ListShi X, Li TC Chan CPS, Chi L, Huang J, Chan DYL
Name of ConferenceThe 33rd Annual Meeting of the European Society of Human Reproduction and Embryology (ESHRE)
Start Date of Conference02/07/2017
End Date of Conference05/07/2017
Place of ConferenceGeneva
Country/Region of ConferenceSwitzerland
Proceedings TitleHuman Reproduction
Volume Number32
Issue NumberSupp 1
PublisherOxford University Press
LanguagesEnglish-United States

Last updated on 2018-20-01 at 18:38