Alkaline and neutral Comet assay profiles of sperm DNA damage in clinical groups

The analysis of sperm DNA fragmentation has become a new marker to predict male infertility, and many techniques have been developed. The sperm Comet assay offers the possibility of differentiating single- and double-stranded DNA (ssDNA and dsDNA) breaks, which could have different effects on fertility. The objective of this study was to perform a descriptive characterization of different groups of patients, such as those with asthenoteratozoospermic (ATZ) with or without varicocele, oligoasthenoteratozoospermic (OATZ) or balanced chromosome rearrangements, as compared with fertile donors. The Comet assay was used to investigate sperm samples for ssDNA and dsDNA breaks. METHODS AND RESULTS The analysis of alkaline and neutral Comet assays in different groups of patients showed different sperm DNA damage profiles. Most fertile donors presented low values for ssDNA and dsDNA fragmentation (low-equivalent Comet profile), which would be the best prognosis for achieving a pregnancy. OATZ, ATZ and ATZ with varicocele presented high percentages of ssDNA and dsDNA fragmentation (high-equivalent Comet assay profile), ATZ with varicocele being associated with the worst prognosis, due to higher levels of DNA fragmentation. Rearranged chromosome carriers display a very high variability and, interestingly, two different profiles were seen: a high-equivalent Comet assay profile, which could be compatible with a bad prognosis, and a non-equivalent Comet assay profile, which has also been found in three fertile donors. CONCLUSIONS Comet assay profiles, applied to different clinical groups, may be useful for determining prognosis in cases of male infertility.