Assessing the Correlation Between Phospholipase C Zeta Measurements and Semen Parameters (PLCZeta)

Despite advances in assisted reproductive technology (ART), significant gaps remain in understanding recurrent implantation failure and abortive embryogenesis. Male factor infertility is globally the leading cause of infertility, and is particularly prevalent in GCC countries, notably the UAE; where fertility rates have halved over the past decade, driven by cultural, lifestyle, and environmental shifts. Poor semen parameters (sperm count, motility, and morphology) account for 41% of infertility cases in the region.

The financial burden is substantial: a single ART cycle can exceed AED 30,000, with couples typically requiring 2-3 cycles (AED 60,000-100,000), translating to an estimated national expenditure of ~AED 0.5 billion annually in fertility treatments alone, excluding associated healthcare investigations.

A critical and underexplored mechanism underlying poor ART outcomes involves oocyte activation, initiated at fertilization by characteristic intracellular calcium (Ca²⁺) oscillations. These are triggered by phospholipase C zeta (PLCζ), a sperm-specific protein delivered into the oocyte upon gamete fusion. Ca²⁺ oscillation profiles directly govern cell cycle progression, embryo gene expression, and early developmental competence; deviations in amplitude or frequency compromise embryo quality. Notably, preimplantation mouse studies show that both insufficient and excessive PLCζ impair blastocyst development, with successful outcomes occurring within a ~4-fold effective dose range - mirroring the natural variation of PLCζ levels observed across fertile men.

Mounting clinical evidence links reduced or absent sperm PLCζ to fertilization failure following intracytoplasmic sperm injection (ICSI), as well as to broader male sub-fertility. PLCζ deficiencies may arise through point mutations, promoter alterations, or disrupted exonic regions, and correlate with known sperm defects including poor motility, globozoospermia, and elevated DNA fragmentation. Crucially, even when residual PLCζ is sufficient to trigger oocyte activation, it may be inadequate for full embryonic competence, a distinction with major clinical implications for sub-fertile men.

Despite this evidence, the direct relationship between sperm PLCζ parameters and downstream outcomes including embryonic efficacy, recurrent implantation failure, and ART success rates has not yet been systematically investigated. We propose that abnormalities in PLCζ-mediated Ca²⁺ oscillations represent a significant and underappreciated contributor to poor global ART outcomes. Establishing this link would position PLCζ as both a prognostic diagnostic marker of sperm health and a therapeutic agent, with the potential to improve outcomes across a broad spectrum of infertility presentations beyond complete fertilization failure.