Aberrant DNA methylation patterns of human spermatozoa in current smoker males.

The purpose of this study was to investigate the impact of current cigarette smoking on sperm DNA methylation patterns. A total of 108 males (51 current smokers and 57 never smoked males) were included in the study. Using 450 BeadChip Arrays, the differentially methylated CpGs between current smokers (n=15) and never smoked males (n=15) were identified. Out of significantly 11 CpGs identified, 2 CpGs namely cg07869343 and cg19169023, which are located in the MAPK8IP3 and TKR genes were selected for further analysis. Using deep bisulfite sequencing in an independent cohort of current smokers (n=36) and never smoked males (n=42), 6 and 1 CpGs showed a significant difference in the MAPK8IP (CpG3, CpG5, CpG6, CpG7, CpG8, and CpG21) and in the TKR (CpG4) were identified, respectively (P≤0.05). Our results indicate that cigarette smoking causes biochemical changes in the sperm DNA methylation in many regions and could adversely affect semen parameters.