Global DNA methylation level in spermatozoa is not associated with ICSI fertilization outcome and embryo quality in donor oocyte programme

Epigenetic mechanisms, including DNA methylation and histone modifications, govern chromatin arrangement in sperm, enhancing motility and safeguarding DNA integrity for accurate epigenetic inheritance. Abnormal methylation is linked to poor sperm quality and fertility issues, underscoring the need to study sperm DNA methylation and its impact on sperm function and embryo development in assisted reproductive technology. In this study, processed spermatozoa from 75 normozoospermic and 15 abnormal ejaculates were examined for sperm global DNA methylation levels using a colourimetric absorbance method. Although semen characteristics were poor in abnormal ejaculates, no significant correlation was found between sperm global DNA methylation levels and sperm characteristics in either normozoospermic or abnormal cohorts. However, mean global DNA methylation levels were significantly lowered in abnormal sperm samples compared to normozoospermic samples (<i>p</i> < 0.05). Furthermore, injecting spermatozoa from these patients (N = 50) into donor oocytes did not show a significant relationship between sperm global DNA methylation and embryo developmental competence. These findings highlight the limitation of sperm global DNA methylation as a biomarker for embryo development and quality.