A dramatic turn has emerged in the case involving a Danish sperm donor who, without knowing it, was a carrier of a genetic mutation that drastically increases cancer risk. In Greece, 18 children in 11 families have been born from this donor’s sperm. In one Greek family where three children were conceived by this donor, one has died of cancer and another is currently ill.

Professor Antonis Kattamis, head of the university oncology unit at Agia Sofia – Marianna Vardinoyannis “Elpida” Children’s Hospital, disclosed the tragic outcome. He said he had spoken with the parents and that they agreed the case should become public to help protect other children. “I thank them,” he added.

According to the professor, the child who passed away was “between 5 and 10 years old,” and “two years later the sibling also developed cancer, and we are now in the treatment phase. We hope for the best, but it is certainly a difficult case,” he said on MEGA.

90% likelihood of developing cancer

“Understandably, there is widespread concern — unfortunately this is a very serious situation. It is one of those cases in which the likelihood of developing cancer during one’s lifetime is extremely high, reaching 90% or more. Of course, no one knows whether cancer will appear in childhood, adolescence, or adulthood. What we do know is that a carrier will develop cancer at some point — and often multiple cancers,” Professor Kattamis had previously stated.

“He had it only in his sperm”

“After the fact, we learned that the donor had donated multiple times, thus spreading this gene. It is a scientifically interesting case because the donor himself does not have the condition. There is a situation called mosaicism, meaning that while all cells in the body are supposed to have the same genetic material, in rare cases some specific cell lines carry a mutation while the rest of the body does not. The donor had the mutation only in his sperm,” the professor explained.

The first cell and the mutation

He continued: “The fact that the donor had it in his sperm does not necessarily mean he could not get ill, but the probability is extremely small or similar to the general population. The offspring, however, receives one gene — one cell — from which all the body’s cells develop. If that first cell carries the mutation, then all cells that multiply will carry it throughout the body.”

Understanding childhood cancer genetics

“In the last 10 years, the scientific community has come to understand that childhood cancer often has a cause. Around 1 in 10 children with cancer carry a predisposing gene. Today, approximately 700 such genes have been identified. Some, like TP53, are very high-risk, while others increase risk but not as dramatically — like the BRCA1 gene associated with breast cancer in women. When cancer will emerge is impossible to predict,” he noted.

Gene study and contact with Belgian researchers

“We have developed a translational molecular hematology–oncology lab over the past decade, funded largely by associations and private citizens. We study these genes to determine whether children with cancer have a predisposition. If we know a child carries such a mutation, we can adjust treatment to avoid creating additional problems. We also screen the family to determine whether the mutation was inherited.

“In the context of this study, we found that our patient had a TP53 mutation. It caught our attention because it had never been recorded before — it appeared for the first time in the mutation database. We presented it at a scientific forum, and colleagues from Belgium approached us saying they had seen the same mutation in many children,” Professor Kattamis revealed.

“Not all of the donor’s children seem to have it”

“Based on the process and what we came to understand — because even we did not realize immediately what the problem was — we suspected it might be donor-related. But because mutations can naturally arise in the body, we weren’t 100% sure it came from the donor,” he said.

Regarding the children born from this donor with the TP53 mutation, he stated: “It appears that a significant portion have it, but not all. We have ruled out the possibility that all the donor’s children carry the mutation.”

He added: “Even if we had known earlier, the only thing that could have been done would be to prohibit this specific donor from donating sperm. The probability of detecting the problem pre-implantation is almost zero. The tests we perform are excellent — people should not feel unsafe. This is a very rare case.”

“There are over 6,000 hereditary diseases. The question is: how many should we test for? There are 700 relevant genes. Should we test for Alzheimer’s? Parkinson’s? All have a genetic component. Should we test every single gene? Would that lead to eugenics? And how ethical would that be?” he asked.

Monitoring

“If you know you carry such a gene, you must undergo lifelong monitoring — demanding, yes, but effective. Cancer is treatable, especially when detected early. We have cases where, thanks to these guidelines, we detected cancer at its earliest stage and successfully treated it,” he said.

“I believe monitoring is essential. It doesn’t mean someone will develop cancer now — it might be in 30 years — but systematic monitoring helps detect it early. And we hope that in 10 years we will have a drug capable of reversing the condition,” he added.