novel large-scale deletion of the mitochondrial DNA of spermatozoa of men in North Iran

ABSTRACT

To investigate the level of correlation between large-scale deletions of the mitochondrial DNA [mtDNA] with defective sperm function. In this analytic study, a total of 25 semen samples of the normozoospermic infertile men from North of Iran were collected from the IVF center in an infertility clinic. The swim-up procedure was performed for the separation of spermatozoa into two groups; [normal motility group and abnormal motility group] by 2.0 ml of Ham's F-10 medium and 1.0 ml of semen. After total DNA extraction, a long-range polymerase chain reaction [PCR] technique was used to determine the mtDNA deletions in human spermatozoa. The products of PCR analysis showed a common 4977 bp deletion and a novel 4866 bp deletion [flanked by a seven-nucleotide direct repeat of 5'-ACCCCCT-3' within the deleted area] from the mtDNA of spermatozoa in both groups. However, the frequency of mtDNA deletions in abnormal motility group was significantly higher than the normal motility group [56, and 24% for 4866 bp-deleted mtDNA and, 52, and 28% for 4977 bp-deleted mtDNA, respectively]. It is suggested that large-scale deletions of the mtDNA is associated with poor sperm motility and may be a causative factor in the decline of fertility in men