From Iceland to Albania and beyond, at least 197 children were conceived with the sperm of donor 7069, an investigation has shown.
And it's possible the number is much higher – although the total number of children conceived with his sperm has not been revealed.
In addition, doctors are unable to say whether everyone has been tested at this point.
So, as they write foreign media, reports the Telegraph, a rare and potentially fatal genetic mutation was sold to families across Europe.
Some of the donor-conceived children have already developed two different types of cancer; others "have already died," said Edwige Kasper, a biologist specializing in genetic predispositions to cancer.
She is counseling some of the affected families.
These details come after it was reported that a sperm donor, who unknowingly carried a genetic mutation that significantly increases the risk of cancer, fathered at least 197 children across Europe, according to a major investigation.
As was further stated, some children have already died and only a minority who inherit the mutation will escape cancer during their lifetime.
The sperm was not sold to UK clinics, but the BBC can confirm that a "very small" number of British families, who have been informed, used donor sperm during fertility treatment in Denmark.
The European Sperm Bank in Denmark, which sold the sperm, said it had "its deepest condolences" to the affected families and acknowledged that the sperm was used to make many babies in several countries.
The investigation was carried out by 14 public broadcasters, including the BBC, as part of the European Broadcasting Union's Investigative Journalism Network.
According to reports, the sperm came from an anonymous man who was paid to donate as a student, starting in 2005. His sperm was then used by the women for about 17 years.
He is healthy and passed the donor screening tests. However, the DNA in some of his cells mutated before he was born.
It damaged the TP53 gene - which plays a crucial role in preventing the body's cells from turning cancerous.
Most of the donor's body does not contain the dangerous form of TP53, but up to 20% of his sperm does.
However, any child born from affected sperm will have the mutation in every cell of their body.
This is known as Li Fraumeni syndrome and comes with a chance of up to 90% of developing cancer, especially during childhood, as well as breast cancer later in life.
"It's a terrible diagnosis," he told BBC-in, Professor Clare Turnbull, a cancer geneticist at the Institute of Cancer Research in London.
MRI scans of the body and brain are needed every year, as well as abdominal ultrasounds, to try to detect tumors. Women often choose to have their breasts removed to reduce their risk of cancer.
The European Sperm Bank said that "the donor himself and his family members are not sick" and such a mutation "is not detected preventively by genetic screening."
However, they said they "immediately blocked" the donor once the problem with his sperm was discovered.
Meanwhile, Dr. Edwige Kasper, a cancer geneticist at the University Hospital of Rouen, in France, who presented the initial data, told the inquiry: "We have many children who have already developed one cancer. We have some children who have already developed two different cancers and some of them have already died at a very young age." /Telegraph/
