Polymorphisms and expression levels of TNP2, SYCP3, and AZFa genes in patients with azoospermia

Abstract

Objective: Azoospermia (the total absence of sperm in the ejaculate) affects approximately 10% of infertile males. Despite diagnostic advances, azoospermia remains the most challenging issue associated with infertility treatment. Our study evaluated transition nuclear protein 2 (<i>TNP2</i>) and synaptonemal complex protein 3 (<i>SYCP3</i>) polymorphisms, azoospermia factor a (<i>AZFa</i>) microdeletion, and gene expression levels in 100 patients with azoospermia. Methods: We investigated a <i>TNP2</i> single-nucleotide polymorphism through polymerase chain reaction (PCR) restriction fragment length polymorphism analysis using a particular endonuclease. An allele-specific PCR assay for <i>SYCP3</i> was performed utilizing two forward primers and a common reverse primer in two PCR reactions. Based on the European Academy of Andrology guidelines, <i>AZFa</i> microdeletions were evaluated by multiplex PCR. <i>TNP2</i>, <i>SYCP3</i>, and the <i>AZFa</i> region main gene (DEAD-box helicase 3 and Y-linked [<i>DDX3Y</i>]) expression levels were assessed via quantitative PCR, and receiver operating characteristic curve analysis was used to determine the diagnostic capability of these genes. Results: The <i>TNP2</i> genotyping and allelic frequency in infertile males did not differ significantly from fertile volunteers. In participants with azoospermia, the allelic frequency of the <i>SYCP3</i> mutant allele (C allele) was significantly altered. Deletion of sY84 and sY86 was discovered in patients with azoospermia and oligozoospermia. Moreover, <i>SYCP3</i> and <i>DDX3Y</i> showed decreased expression levels in the azoospermia group, and they exhibited potential as biomarkers for diagnosing azoospermia (area under the curve, 0.722 and 0.720, respectively). Conclusion: These results suggest that reduced <i>SYCP3</i> and <i>DDX3Y</i> mRNA expression profiles in testicular tissue are associated with a higher likelihood of retrieving spermatozoa in individuals with azoospermia. The homozygous genotype TT of the <i>SYCP3</i> polymorphism was significantly associated with azoospermia.