Scientists believe they have isolated the gene that causes infertility in men – a discovery that will pave the way for new treatments.
The gene, known as ZNF214, is believed to prevent some men from producing sufficient sperm cells.
Dutch researchers carried out tests on human testicle cells and mice to try to find exactly how the gene impacts on sperm production.
The gene is located on a chromosome region linked to Beckwith Wiedemann Syndrome.
BWS is a complex disorder which causes boys to be born with undescended testicles and suffer from infertility as adults.
“ZNF214 could be involved in male subfertility, and we decided to test whether this was the case,” Dr. Judith Gianotten of the Amsterdam Academic Medical Center told the BBC.
Her team found an unusual distribution of DNA variants in the gene in men with low fertility, indicating a link.
They then compared the DNA of 77 men with very low sperm counts and 65 men with normal sperm counts.
In three individuals from the infertile group, three new variants of the ZNF214 gene were found. These did not appear among men in the “normal” group.
For two that had one of the gene variants, DNA from their parents showed they had inherited the mutation from their moms.
All three appeared normal in other respects, and none had any symptom of BWS – although one did have a medical history of undescended testicles.
The fact that the mutation appeared to be inherited from the mother explained how infertility due to impaired sperm production can be passed on to the next generation, Gianotten said.
If it was inherited from the father, then the mutation would be wiped out of the population.