A sperm donor whose samples helped conceive nearly 200 children across Europe unknowingly carried a cancer-causing genetic mutation — a hidden risk now tied to multiple childhood illnesses and early deaths.

An investigation led by the BBC and many other public service broadcasters revealed that the donations were made to Denmark’s European Sperm Bank (ESB). Those donations were then used by 67 fertility clinics in 14 countries over a 17-year span.

The donor, who was not identified, was paid to donate as a student beginning in 2005, according to the report.

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Although the donor passed the initial health screenings, he had hidden genetic mutations that damaged the TP53 gene, which helps to prevent cancer by repairing DNA damage or trigger the death of cancer cells.

When TP53 is mutated, those protective functions are lost, which can lead to uncontrolled cell division, accumulation of mutations and tumor growth, research has shown.

Up to 20% of the man’s sperm would contain that mutated gene, and any children conceived from that affected sperm would have the mutation in every cell of their body, the BBC report stated.

As a result, these children would have a 90% risk of developing some type of cancer in their lifetime, including breast cancer, bone cancers, brain tumors and leukemia. This heightened risk is known as Li Fraumeni syndrome.

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Doctors raised these concerns at the annual congress of the European Society of Human Genetics (ESHG), which was held in Milan in May 2025.

At that conference, Edwige Kasper — a specialist in cancer genetics at Rouen University Hospital in France — presented the case of the sperm donor whose genetic material carried the harmful variant.

“This is the abnormal dissemination of genetic disease. Not every man has 75 children across Europe.”

It was reported that 23 children had been confirmed to have the variant at that time, 10 of which had already been diagnosed with cancer. 

The actual number is likely much higher, the report surmised, as at least 197 children were born from the donated sperm — but not all data has been collected. 

Kasper called for a limit on the number of births or families for a single donor in Europe.

“We can’t do whole-genome sequencing for all sperm donors — I’m not arguing for that,” she said. “But this is the abnormal dissemination of genetic disease. Not every man has 75 children across Europe.”

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She also recommended that children born from this donor’s sperm undergo genetic counseling.

“We have some children that have already developed two different cancers, and some of them have already died at a very early age,” Kasper recently told the investigators.

There is no worldwide law that limits how many times a donor’s sperm can be used or how many children may be born from a single donor, according to the European Society of Human Reproduction and Embryology (ESHRE).

However, individual countries may have their own rules or guidelines surrounding sperm donor usage. The ESHRE recently proposed a cap of 50 families per donor as an international limit.

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Dr. Marc Siegel, Fox News senior medical analyst, commented on these developments to Fox News Digital.

“This awful story emphasizes the growing need for up-to-date genetic screening for all donors,” he said. “It also provides context for the idea that knowing the donor provides an advantage.”

“Genetic screening, including for oncogenes (genes that have the potential to cause cancer) is improving dramatically, and all use of sperm donations must include it,” Siegel went on. 

He also called for AI to be used to improve and speed up the process.

“When a propensity for disease is suspected, the sperm must be discarded,” the doctor added.

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In a statement sent to Fox News Digital, ​​the European Sperm Bank expressed “deepest sympathy” for the families involved.

“We are deeply affected by the case and the impact that the rare TP53 mutation has on a number of families, children and the donor. They have our deepest sympathy,” the ESP said.

“ESB tests and performs an individual medical assessment of all donors in full compliance with recognized and scientific practice and legislation.”

In the case of this particular sperm donor with the TP53 mutation, the ESB noted that it occurs only in a small part of the donor’s sperm cells and not in the rest of the body.

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“In such cases, the donor himself and his family members are not ill, and a mutation of this type is not detected preventively by genetic screening,” the agency said.

When the ESB later confirmed the mutation in 2023, the donor was “immediately blocked” and authorities and clinics were notified.

“Donors should be healthy and have no history to suggest hereditary disease.”

“The clinics are responsible for informing the patients, partly because we as a sperm bank do not necessarily know the patients, and because the patients’ own treating physicians are best equipped to advise them in the specific situation,” the agency stated.

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When contacted by Fox News Digital, the American Society of Reproductive Medicine (ASRM) provided its guidance on embryo and gamete donation, which stated in part that all prospective donors should undergo “appropriate genetic evaluation.”

“Donors should be healthy and have no history to suggest hereditary disease,” the ASRM continued. 

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Parents with concerns are encouraged to contact both their treating clinic and the relevant fertility authority in that country.