Sperm donor with cancer-linked gene mutation fathered nearly 200 children across Europe

A major investigation has revealed that a sperm donor carrying a dangerous genetic mutation – one that dramatically increases cancer risk – fathered at least 197 children across Europe over a 17-year period.

Some of the affected children have already died, while experts warn that most of those who inherited the mutation face a lifetime of elevated cancer risk.

The investigation, conducted by 14 public service broadcasters, including the BBC, under the European Broadcasting Union's Investigative Journalism Network, found that the sperm came from an anonymous donor who began donating as a student in 2005.

Although he passed routine screening and remains healthy, a mutation in some of his cells had damaged the TP53 gene, which plays a critical role in preventing cells from becoming cancerous.

Up to 20% of the donor's sperm carried the TP53 mutation, meaning any resulting children would have the defect in every cell of their body. The condition, known as Li Fraumeni syndrome, carries up to a 90% likelihood of developing cancer, often in childhood, and later includes a high risk of breast cancer.

"It is a dreadful diagnosis," Prof Clare Turnbull, a cancer geneticist at the Institute of Cancer Research in London, told the BBC. "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 – based in Denmark and responsible for distributing the donor's sperm – said the donor and his family members are not ill and that such mutations cannot be detected by routine genetic screening.

The bank added that it "immediately blocked" the donor once the issue was identified and expressed its "deepest sympathy" to affected families. It acknowledged that limits on how often a donor's sperm can be used had been exceeded in some countries.

Doctors began raising alarms earlier this year after children conceived by the donor began turning up with cancer linked to the TP53 mutation.

Dr Edwige Kasper, a cancer geneticist at Rouen University Hospital in France, said, "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."

One French mother, identified only as Céline, learned her 14-year-old child had inherited the mutation after a call from her fertility clinic. She said she bears "absolutely no hard feelings" toward the donor but believes it was unacceptable that she was given sperm that "wasn't clean, that wasn't safe, that carried a risk."

She said she now lives with the constant fear of when and how cancer might develop in her child. "We don't know when, we don't know which one, and we don't know how many… I understand that there's a high chance it's going to happen and when it does, we'll fight and if there are several, we'll fight several times."

The donor's sperm was used by 67 fertility clinics across 14 countries. While none of the sperm was sold to UK clinics, a "very small number" of British women travelled to Denmark for treatment and have been notified.

Peter Thompson, chief executive of the UK's Human Fertilisation and Embryology Authority, said they had been informed "by the Danish clinic at which they were treated."

Experts say the case raises urgent questions about donor limits and international regulation. Prof Allan Pacey of the University of Manchester called the case "awful" but warned that "you can't screen for everything," noting that only 1–2% of donor applicants are accepted under existing standards.

Some advocacy groups, including the Progress Educational Trust, argue that the larger issue is the psychological impact on children discovering hundreds of half-siblings worldwide, urging tighter global restrictions on donor usage.

Despite the concerns, experts stress that using licensed clinics still offers a high level of safety, with extensive screening compared to natural conception.