Fears of hereditary cancer transmission to dozens of children from a sperm donor: At the annual conference of the European Society of Human Genetics held in Milan, one of the most alarming cases in the world of fertilization was revealed: a sperm donor from Europe, who carried a rare genetic mutation linked to the development of cancer, gave birth to at least 67 children in eight different countries – ten of whom have now been diagnosed with cancer . The case caused a stir and led to new calls for restrictions on the number of children that can be born from sperm donations from a single person.

The scandal began when two different families separately contacted their fertility clinics after their children were diagnosed with a rare cancer. Genetic testing revealed that both families had a mutation in the TP53 gene – a mutation linked to Li-Fraumeni syndrome, one of the most serious hereditary syndromes that leads to an increased risk of a variety of cancers, including leukemia, breast cancer, and brain cancer.

The TP53 gene is sometimes called the "guardian of the genome," as it is involved in repairing DNA damage and protecting cells from cancerous changes. Li-Fraumeni syndrome occurs rarely, but the risk of developing cancer in those who carry the mutation in it reaches tens of percent even at a young age.

According to the report, the mutation was not known to be linked to cancer at the time of the donation, which began in 2008, and could not be detected using the standard tests conducted at the time. However, it is now well known, and is considered extremely dangerous. A laboratory that tested the mutation in France determined that it was a clearly carcinogenic mutation, and it was recommended that all children born from the donation be referred for genetic counseling and regular medical supervision.

Genetic tests conducted across Europe, in collaboration with genetics and pediatric units, revealed that 23 of the 67 children do indeed carry the mutation . Ten of them have already developed cancer, including cases of leukemia and lymphoma. The medical recommendation for them includes periodic follow-ups, MRI scans of the body and brain, and breast and abdominal examinations in adulthood.

The European Sperm Bank, which provided the samples, confirmed that this donor had indeed fathered more than 67 children, but declined to disclose the exact number. Its policy, it said, limits the number of families to 75 per donor. However, in cases of cross-border donations, there is currently no uniform mechanism in Europe to track the number of children from a particular donor or to inform all clinics of unusual medical cases .

Dr. Edwig Kasper , a biologist at the University Hospital of Rouen in France who led the study, warned: "This is a clear case of the spread of a genetic disease on an extraordinary scale. Not every man fathers 75 children all over Europe." She said that while it is not necessary to perform full genetic sequencing on every sperm donor, a stricter limit on the number of children from each donor and strict international reporting are needed.

Prof. Nikki Hudson of De Montfort University in the UK also warned of the dangers. She said, "When human gametes are sent to other countries and used for fertilization in large numbers, it is very difficult to trace all the children in the event that a genetic or medical problem is discovered."

A spokeswoman for the European Sperm Bank admitted that the affair had shaken those involved. “The donor had undergone all the usual tests, but there is no way to identify rare genetic mutations if you don’t know in advance what to look for ,” she said. The bank supports a clear international limit on the number of families per donor, she said, and has been working to advance the issue for several years.

The current case joins a number of cases in recent years that have raised questions about ethics, safety, and oversight in the field of donations. For example, a Dutch donor who was known to have fathered over 500 children, some in the same city, sparked panic at the time due to fears of unconscious genetic kinship between offspring.

On the medical front, experts emphasize that parents of children born through sperm donations now need to be more aware, and fertility clinics must establish shared databases and share relevant medical information with each other. This requirement is exacerbated by the limited ability of parents and children to know about the existence of half-siblings in other countries.