Identification of novel homozygous missense and deletion mutations manifesting oligospermia infertility in Kashmiri population

Abstract

Background: Human male infertility has a lot of known molecular components that have an accurate diagnosis, such as Y chromosome deletion and monogenic causes. Only 4% of all infertile males are diagnosed with genetic causes, while 60-70% of infertile men remain without an accurate diagnosis and are classified as unexplained. Oligospermia is a major cause of human male infertility. Its etiology and pathogenesis are linked to genetic abnormalities. The majority of genetic causes related to human male infertility remain unclear.

Results: Generally, we found a significant association between the specific type of disease and gender (p = 0.003), and the regression value (R² ) for this association was 0.75. Association of the type of disease with body mass index was not significant (p = 0.34). There was no statistically significant difference (p = 0.40) among disease types with patients occupations. All explored mutations are listed for primary and secondary infertility in relation to the oligospermia condition. p.Arg286X is the outcome of a mismatch mutation in which the nucleotide change resulted in the substitution of Arg (arginine) amino acid with X (any amino acid) at position 286 in the Hyal3 gene of primary infertile patients having oligospermia. In primary infertile patients with the p.Arg286X mutation, a frameshift deletion mutation was also found just after the 25 nucleotide sequences of the Hyal3 genes of the second mutated exon. This deletion mutation was only detected in patients with primary infertility and was not found in people with secondary infertility or healthy controls. The other mutations in secondary infertile patients with oligospermia were: p.Lys168Ser, replacement of lysine (Lys) with serine (Ser) at position 168; p.Lys168The, replacement of lysine (Lys) with threonine (The) at position 168; p.His113X, substitution of histidine (His) with an unknown amino acid (X) at position 113; p.Pro162X, substitution of proline (Pro) with an unknown amino acid (X) at position 162; and p.Phe157X, phenylalanine (Phe) substitution with an unknown amino acid (X) at position 157.

Conclusion: This study clarifies the site of novel mismatch and frameshift deletion mutations in the Hyal3 gene in primary infertile oligospermia patients.

Keywords: DNA sequencing; Hyal3 gene; exon and intron; human male infertility; novel mutation; oligospermia.