An experimental test could identify cases of male infertility that are caused by genetic abnormalities hindering sperm’s ability to puncture an egg.
 suggest that 1 in 6 people globally are affected by infertility at some point in their life, with the cause often being unknown.
When investigating male infertility, doctors evaluate sperm volume, numbers, shape and motility. If all these factors come back “normal”, the cause of the infertility is often categorised as “unexplained”.
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But suggests that dysfunction to the so-called Catsper genes, expressed in the testicles, impedes sperm’s ability to hyperactivate – a critical process of fertilisation when sperm beat in a rapid, powerful pattern that punctures the egg’s coat.
at the University of MĂĽnster in Germany and his colleagues have therefore developed a test that indicates whether these dysfunctional genes may be present and causing infertility.
For the test, a semen sample is added to a solution that creates an environment that causes sperm to stop swimming, but only if the Catsper genes are functioning as they should. “If the Catsper is dysfunctional, the sperm ignores this hostile environment and continues to swim,” says Young.
Over three years, the researchers tested the semen of 2286 men who were part of a couple having an intracytoplasmic sperm injection (ICSI), a form of fertility treatment that involves injecting a single sperm into an egg. No transgender people were included in the study.
Nine of these men had abnormal sperm function that suggested dysfunction to their Catsper genes, as assessed by the test.
Among such men, intrauterine insemination – a fertility treatment in which sperm is directly inserted into the uterus – and in vitro fertilisation (IVF) – in which an egg is removed from the ovaries and fertilised with sperm – will probably be ineffective, as their sperm are still unable to puncture, and ultimately fertilise, the egg, says Young.
The so-called CatSper-Activity-Test could save people time and money by directing them straight to ICSI, he says.
at the University of Geneva, Switzerland, says that there are probably many causes of infertility, but a test like this could save some people time and money that may otherwise be spent on ineffective fertility treatments.
“This is a quick and easy test for men whose semen appears normal in terms of motility, morphology and concentration, but [for unexplained reasons] still can’t achieve pregnancy,” she says.
medRxiv
