A novel mtDNA deletions are associated with diminished fertility in Iraqi human sperm

Relationships between the genetic factors including sperm mtDNA mutations and diminished fertility and motility of human spermatozoa was evaluated in 30 fertile donors who had normospermic semen characteristics and from 50 subfertile or infertile patients. The latter included 23 with oligospermia, and 27 with asthenospermia males. Using long-range polymerase chain reaction (PCR), we confirmed the 4977 bp , 7345 bp and 7599 bp deletion of mtDNA in the spermatozoa with poor motility. The results showed that the ratio of the deleted mtDNA in the spermatozoa with poor motility and diminished fertility were significantly higher than those in the spermatozoa with good motility and fertility. In addition, we found that the frequencies of the three large-scale deletions in the spermatozoa from patients with asthenospermia and oligospermia were higher than those of the fertile males. Our findings suggest that mtDNA deletions may play an important role in some pathophysiological conditions of human spermatozoa. Mitochondrial genes ATPase6, Cytb, and ND1, were amplified by PCR and then analyzed by direct sequencing. However, a total of 75 different nucleotide substitutions were identified in the examined mitochondrial genes in both groups, all of which are statistically non-significant. sixteen substitutions caused an amino acid change and 37 were considered novel mutations. As a conclusion, mtDNA mutations in male infertility should be examined in larger numbers in order to clarify the effect of genetic disorders.