Sperm contribute DNA to a pregnancy and also signalling to the egg to begin development. A sperm protein signal called phospholipase C zeta (PLCzeta) triggers calcium signals inside the egg, starting a process known as egg activation.
If this protein is missing or does not function properly, fertilisation may fail even after IVF with ICSI where the the sperm is placed inside the egg. In some men, an lteration in PLCZ1, gene responsible for making PLCzeta can be the reason eggs do not fertilise.
Following repeated failed or very low fertilisation, genetic testing may help identify a sperm-related cause. Understanding why this is happening can support treatment planning and discussions about inheritance. However, genetic testing will not explain every case, and an uncertain finding might not impact the g the amount of PLCzeta protein in sperm.
For selected patients assisted oocyte activation often referred to in clinics as AOA can be helpful to overcome the missing signal. Assisted activation should be considered individually, rather than used routinely and your fertility team should discuss its suitability and the remaining uncertainties about safety and longer-term outcomes.
Fertilisation difficulties can involve sperm, eggs or a combination of factors. At Fertility Genetics, we help individuals and couples understand genetic findings alongside their treatment history, supporting informed decisions about their next steps.
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