Researchers have uncovered a disturbing trend in reproductive medicine, where a single sperm donor’s genetic mutation has been linked to cancer in 10 children. The case has highlighted the critical need for improved genetic screening protocols and a reevaluation of the number of births allowed from a single donor. The donor, whose sperm was used in at least 67 pregnancies, carried a rare mutation in the TP53 gene, associated with Li-Fraumeni syndrome, a condition that increases the risk of various cancers. This mutation, which would not have been detectable through standard screening methods at the time of donation in 2008, has now been identified after two families separately reported their children’s cancer diagnoses to their fertility clinics. Dr. Edwige Kasper, a biologist at Rouen University Hospital in France, presented this case at the European Society of Human Genetics’ annual conference in Milan last week, emphasizing the need for European-wide regulations on the number of families a single donor can influence. She noted that while comprehensive whole-genome sequencing is not feasible for all donors, the current screening practices are insufficient to prevent the spread of such genetic mutations. The European Sperm Bank confirmed that the donor’s mutation was present in some of his genetic material but stated that the screening methods used at the time would not have detected it. They also highlighted their own proactive limit of 75 families per donor, but acknowledged that even this cannot ensure the detection of all potential genetic risks. This incident has raised serious questions about the long-term health impacts of using sperm from a single donor and the need for more comprehensive screening and regulatory oversight. While the donor is currently in good health, the case underscores the importance of balancing reproductive freedom with the potential for genetic risks. The American Society for Reproductive Medicine (ASRM) has recommended that donors are limited to 25 live births within each population area of 800,000 people, but such measures are not universally enforced. As the case continues to draw attention, experts are calling for a more nuanced approach to addressing the complexities of genetic screening and donor limits in reproductive medicine.