Background: The cationic channel of sperm is a small family of ion channels, named after the first putative cation channel of sperm (CatSper). It is a sperm-specific, pH-sensitive, voltage-gated calcium channel, Ca2+selective and located in the principal piece of the flagellum. CatSper 1 gene is located on chromosome 11q13.1 and is involved in sperm motility and hyperactivation (HA). We designed our study with an aim to investigate the CatSper 1 gene mutation in infertile men and correlated it with clinico-pathological findings.
Materials and methods: We performed mutational analysis of the CatSper 1 gene in 100 infertile men and 100 healthy controls. To screen mutations in CatSper 1 gene, we performed PCR followed by Single Stranded Conformational Polymorphism (SSCP). Samples showing shifts in bands were direct DNA sequenced.
Results: On analysis of mutational screening of CatSper 1 gene, we found one silent mutation in exon 2 in 10 asthenozoospermic males due to a single nucleotide change (CGG → AGG) at codon 457. This is a silent mutation as there is no alteration in amino acid sequence. In addition, at exon 5, change in nucleotide from CAG → CAT inferred change of amino acid from glutamine to histidine at codon 624 (Gln624His) in three asthenozoospermic males. This is a missense mutation. Conclusions: On analysis of mutational screening of CatSper 1 gene, at exon 2 and 5 there was a silent and missense mutation respectively. In case of change of amino acid from glutamine to histidine (Gln624His) both the amino acids are polar and positively charged. However histidine is aromatic due to which there might be changes in structural conformation of protein product formed. All the mutations were found in different cases. It is important to note that these predictions have been made on the basis of the identified DNA alterations at the genomic level and that additional studies are required for confirmation at the transcriptional or translational level.
