Genomic analysis of missense and silent mutations in CatSper 2 gene in infertile male cases.

Abstract

Background: Infertility is described as inability of a couple to conceive after a period of one year regular unprotected intercourse. About 10% - 15% of couples experience some form of infertility. Male infertility is a multifactorial disease process with a number of potential contributing causes; several factors may contribute to its etiology. Cation channels of sperm is a small family of ion channels, normally referred to as CatSper channels (CatSper1, 2, 3 & 4) which are putative six-transmembrane (6TM) spanning proteins and seem to be specific to sperm cells. CatSper 2 gene involved in sperm motility and hyper activation. Materials and methods: We performed mutational analysis of the CatSper2 gene in 100 infertile males and 100 healthy controls. To screen mutations inCatSper2 gene, we performed PCR followed bydirect DNA sequencing. Results: Analysis of mutational screening of CatSper2 gene, we found a single nucleotide change (CT G →CT A ) in five asthenozoospermia at exon 3 resulting in silent mutation and (C G T→C C T)in eight asthenozoospermia at exon 6 missense mutation as the change leads to amino acid sequence change from Arginine to Proline. Conclusions: On mutational screening of CatSper2 gene, at exon 6 there was missense mutation that leads to conformational structural change inspite of the amino acids being hydrophobic and non-polar in nature. The identified mutations may be a cause of asthenozoospermia in humans.