Mitochondrial Genetic Variation in Iranian Infertile Men
Several recent studies have shown that mitochondrial DNA mutations lead
to major disabilities and premature death in carriers. More than 150 mutations in
human mitochondrial DNA (mtDNA) genes have been associated with a wide spectrum of
disorders. Varicocele, one of the causes of infertility in men wherein abnormal inflexion
and distension of veins of the pampiniform plexus is observed within spermatic cord, can
increase reactive oxygen species (ROS) production in semen and cause oxidative stress
and sperm dysfunction in patients. Given that mitochondria are the source of ROS
production in cells, the aim of this study was to scan nine mitochondrial genes (
Materials and Methods:
In this cross-sectional study, polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing were used to detect and identify point mutations respectively in 9 mitochondrial genes in 72 infertile men with varicocele and 159 fertile men. In brief, the samples showing altered electrophoretic patterns of DNA in the SSCP gel were sent for DNA sequencing to identify the exact nucleotide variation.
Ten type nucleotide variants were detected exclusively in mitochondrial DNA of infertile men. These include six novel nucleotide changes and four variants previously reported for other disorders.
Mutations in mitochondrial genes may affect respiratory complexes in combination with environmental risk factors. Therefore these nucleotide variants probably lead to impaired ATP synthesis and mitochondrial function ultimately interfering with sperm motility and infertility.