Genetic variants in QRICH2 gene among Jordanians with sperm motility disorders.

Abstract

Sperm motility, a key determinant of male fertility, is often impaired by genetic variations affecting flagellar formation. The glutamine-rich protein 2 (QRICH2) gene encodes a protein essential for sperm flagella biogenesis and structural integrity. This study investigates genetic variations within exon 3 of the QRICH2 gene, identifying novel heterozygous variants associated with sperm tail-specific abnormalities and motility impairments. Among 34 individuals diagnosed with asthenozoospermia (ASZ) and 26 individuals with normal sperm parameters (NZ) from Jordan, eight unique heterozygous variants (c.123 G>T, c.133 G>C, c.138A>G, c.170A>C, c.189C>G, c.190T>C, c.195A>T, and c.204A>T) were exclusive to the ASZ group, while four variants (c.136 G>A, c.145A>C, c.179T>G, and c.180T>G) were found only in NZ. These variants were absent from major genetic databases, suggesting their potential novelty, while two variants (c.206C>T and c.189C>T) were linked to known SNP cluster IDs rs73996306 and rs1567790525, respectively. Four non-synonymous SNPs (c.136 G>A, c.145A>C, c.170A>C, and c.204A>T) were predicted to be functionally and structurally damaging, underscoring their significance. Additionally, five variants overlapped with previously reported mutation sites, indicating potential mutation hotspots. Statistical analysis revealed a significant association between QRICH2 mutations and tail defects (p < 0.021). These findings highlight the critical role of heterozygous QRICH2 mutations in mild-to-moderate ASZ, even in NZ individuals. Despite some carriers meeting WHO criteria for NZ, notable morphological abnormalities suggest the need for refined diagnostic benchmarks. Screening for QRICH2 mutations is essential for accurate molecular diagnosis and should be integrated into genetic counseling, particularly in regions like Jordan. Further research into the cumulative effects of heterozygous mutations and their environmental interactions is needed to expand our understanding of idiopathic male infertility and to enhance diagnostic and therapeutic strategies for male infertility.