Investigation Reveals Sperm Donor with Cancer-Causing Gene Fathered Nearly 200 Children Across Europe

A comprehensive investigation has uncovered that a sperm donor carrying a rare cancer-causing genetic mutation has unknowingly fathered at least 197 children across Europe. The donor's sperm was distributed by the European Sperm Bank (ESB) based in Copenhagen to 67 clinics spanning 14 countries. The mutation leads to Li-Fraumeni syndrome, which has already caused some children to develop cancer, with several tragically dying at very young ages. This particular mutation wasn't detected during initial screenings as it was a previously unidentified variant not included in standard genetic testing protocols at the time of donation.

The extensive investigation was conducted collaboratively by 14 public service broadcasters, including the BBC, as part of the European Broadcasting Union's (EBU) Investigative Journalism Network.

The anonymous donor began contributing to sperm banks as a university student in 2005 and continued for several years. His donations were used by numerous women to conceive children over a 17-year period. Though the donor himself is healthy and successfully passed all standard screening tests, a mutation had occurred in some of his cells before birth. This mutation affected the critical TP53 gene, which normally functions to protect the body from cancer by regulating abnormal cell growth.

While the majority of the donor's body doesn't contain the mutated TP53 gene, approximately 20% of his sperm carry the mutation. When a child is conceived using affected sperm, the mutation appears in every cell of that child's body, substantially increasing their cancer risk. The European Sperm Bank identified the donor in November 2023.

Li-Fraumeni syndrome is a rare genetic disorder that dramatically increases cancer risk. It frequently leads to childhood cancers, including brain tumors and sarcomas, as well as breast cancer in adulthood. Individuals with this syndrome require rigorous monitoring through annual full-body and brain MRI scans and abdominal ultrasounds to detect tumors early. Many women with this mutation opt for preventative mastectomies to reduce their cancer risk.

Professor Clare Turnbull, a cancer geneticist at London's Institute of Cancer Research, told the BBC: "It is a dreadful diagnosis. It's a very challenging diagnosis to land on a family, there is a lifelong burden of living with that risk, it's clearly devastating."

The European Sperm Bank has stated that the donor and his family remain healthy, emphasizing that this specific mutation isn't typically detected during standard genetic screening procedures. Once the issue was identified, they immediately removed the donor from their program.

The ESB was initially alerted in 2020 when a child conceived with the donor's sperm was diagnosed with the mutation. However, the bank initially concluded the test was negative and reintroduced the sperm to their catalog. Only after a second case emerged in 2023 was the donor permanently blocked from the program.

Initial findings identified 23 out of 67 children carrying the TP53 gene variant, with 10 already diagnosed with cancer. Further investigation revealed the donor fathered at least 197 children throughout Europe, though the exact number remains uncertain due to incomplete data from some countries. The total number of children who inherited the variant is still unknown.

Dr. Edwige Kasper, a cancer geneticist at Rouen University Hospital in France who presented the initial findings, told investigators: "We have many children that have already developed a cancer. We have some children that have developed already two different cancers and some of them have already died at a very early age."

The investigation also revealed that the donor's sperm was used to conceive far more children than the ESB's self-imposed limit of 75 families, and exceeded national limits in countries including Belgium and Spain. This has highlighted serious concerns regarding the lack of international regulation and tracking systems for sperm donors.