Multiplex Semen Molecular Profiling Supplements Traditional Sperm Analysis Toward a Targeted Therapy of Male Infertility

To the Editor.—Male factor infertility (MFI) accounts for approximately 50% of sterility cases, and infertility affects approximately 15% of couples globally.1 Traditional semen analysis provides fundamental information regarding the sperm count, motility, and morphology, yet reference values for semen parameters are not standardized for accurate assessment of MFI.1,2 Furthermore, semen analysis fails to divulge the underpinning pathways that involve a broad spectrum of gene alterations and protein and epigenetic modifications that affect spermatogenesis and the fertilization process.3–5 Hence, the global trend toward a worsening of sperm parameters, induced by western civilization and delay of childbearing age, is amplified by belated and inadequate diagnostic inquiry, augmenting misdiagnosed incidents to 15%.6 Effective screening programs and evidence-based therapy have succeeded in steadily decreasing the proportion of the most common causes historically (eg, varicocele and cryptorchidism).3,7 Nowadays, idiopathic cases approach 60%, emphasizing that scrutiny of molecular profiles in advance of therapeutic interventions may reverse this rising prevalence.6Recent investigation has focused on novel molecular biomarkers with significant diagnostic and prognostic value that will be reflected in targeted therapies. DNA fragmentation index (DFI), microRNA (miRNA), genetic status, proteomic profiling, and DNA methylation have emerged as indicators of sperm fertilization potential.7–9 Seminal oxidative stress is a major cause of MFI, triggering sperm DNA damage and alterations of crucial proteins (eg, acrosome reaction and flagellar movement) in 80% of idiopathic cases.9 Seminal proteomic studies have revealed that aberrant protein expression affects spermatozoa structure and function and spermatogenesis. Likewise, sperm DNA fragmentation reflects chromatin destruction and affects physiologic sperm functions and genetic information transmission.9 DFI is a parameterization of sperm DNA fragmentation with normal cutoff below 15%. It is positively related to aging and abortion rate and negatively correlated with sperm survival rate, sperm concentration, pregnancy rate, and antioxidant capacity, highlighting DFI’s impact on fertilization and embryogenic development.9 Elevated DFI greater than 30% is a bad prognostic index with clinical significance for commencement of defragmentation therapy with antioxidants. Currently, the most sensitive methods for assessing DFI are the sperm-chromatin structure or sperm-chromatin dispersion assay, the single-cell gel electrophoresis or comet assay, and the terminal deoxynucleotidyl transferase–mediated biotin–deoxyuridine triphosphate nick-end labeling assay. This assay via fluorescence microscopy and flow cytometry can equally diagnose MFI and accurately predict pregnancy rate.9 Nevertheless, the subcellular understanding of MFI is accomplished by a cost-effective proteomic analysis, based on advanced automated techniques rather than DFI computation.7Concurrently, the diverse spectrum of sperm RNAs has been shown to play a pivotal role in fertility and postfertilization development, highlighting the importance of incorporating RNA biomarkers into multiplex diagnostic panels for investigating idiopathic infertility and exploring novel RNA-based therapeutic strategies.8 Next-generation transcriptome sequencing revealed that differentiation in miRNA, transfer RNA–derived small RNA (tsRNA), and ribosomal-derived small RNA profiles depicts fertility diversity. However, further investigation is needed to designate the appropriate type, among long RNAs (messenger RNAs and long noncoding RNAs) and their degradation products, small RNAs (miRNAs, Piwi-interacting RNAs), transfer RNA–derived small RNAs, ribosomal-derived small RNAs, small nuclear RNAs, small nucleolar RNAs, mitochondrial tRNAs, mitochondrial ribosomal RNAs, and endogenous small interfering RNAs, that will serve as an accurate predictor.8The rising burden of MFI behooves scientists to revise World Health Organization diagnostic criteria and impose optimal personalized therapy by incorporating DFI, miRNAs, and proteomic profiling in a multiplex analysis based on pioneering molecular technologies.