A Novel Large-Scale Deletion of The Mitochondrial DNA of Spermatozoa of Men in North Iran

BACKGROUND: To investigate the level of correlation between large-scale deletions of the mitochondrial DNA (mtDNA) with defective sperm function. MATERIALS AND METHODS: In this analytic study, a total of 25 semen samples of the nor- mozoospermic 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. RESULTS: 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). CONCLUSION: 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.