Nahid Khosronezhad
Abasalt Hosseinzadeh Colagar
Seyed Mohsen Mortazavi
Esmat Ghalkhani

The Nsun7 gene, which encodes protein of putative methyltransferase Nsun7, has a role in sperm motility in mice. In humans, this gene is located on chromosome4. Since no similar studies have beenconducted in humans, so the aim of the present study was to investigate mutations of exon4 in the fertile (normospermic) and infertile asthenospermic (with reduced sperm motility) men. Semen samples were collected from the Omid and Fatemezahra IVF centers (Babol, Iran) and analyzed on the basis of World Health Organization (WHO) guidelines. Using general phenol–chloroform DNA extractionmethods. Exon4 was amplified using Sun-F and Sun-R primers. The exon4 PCR fragments were then dissected by PAGE to ensure that there were no additional bands, and then samples were sent to sequencing for further identification of possible mutations. Direct sequencing of polymerase chain reaction (PCR) products, along with their analysis, confirmed deletion mutation of adenine in location 11337 of Nsun7 gene in asthenospermic men. Comparison of normal and mutant protein structures of Nsun7 indicated that the through A11337-Deletion mutation was converted to stop codon and protein can be shorter than normal. Analysis of extracted proteins of the sperm showed that rate of the Nsun7 protein was reduced. Because Nsun7 gene products have a role in sperm motility, if a mutation occurred in exon4 of this gene, it would lead to impairment in activity of the protein and motility of sperm flagella, that causing sperm motility defect and infertility

Nsun7 gene, Asthenospermic, Sperm motility, A11337-Deletion mutation, Male infertility, Deletion mutation