At least 67 children have been born in Europe from sperm donation from a man with a genetic mutation that predisposes him to cancer.

The families of dozens of children in Europe, born through sperm donation in Denmark, discovered several years after their birth that the donor carried a genetic variant that promotes the development of early-onset cancers, Le Figaro and The Guardian reported on Saturday, May 24.

This case is to be presented this Saturday by Edwige Kasper, a doctor of pharmacy and oncogenetic biologist at Rouen University Hospital, at a conference of the European Society of Human Genetics in Milan. It came to light when two families contacted their fertility clinics after their children, born from sperm donation, developed cancers that appeared to be linked to a rare genetic variant. A genetic variant, also called a genetic mutation, refers to "a change in a gene that can be responsible for a genetic disease," according to the French Biomedicine Agency .

Contacted by the doctor of one of the French families who benefited from this donation, biologist Edwige Kasper studied this variant: "I came to the conclusion that the variant was probably carcinogenic and that children born to this donor should benefit from genetic counseling," she explains to the Guardian. This genetic mutation is likely to cause Li-Fraumeni syndrome , which manifests itself by the early onset of various malignant tumors.

Contacted by Le Figaro, the Danish sperm bank that received this donation stated that this variant could not have been detected in advance. "Sperm donors undergo a thorough medical examination, an analysis of family history, and tests to detect possible genetic and infectious diseases," the Danish company explained. "However, it is impossible to reduce all risks and, in this specific case (...), systematic or preventive screening methods would not have been able to detect this mutation," it added.

"Each human being has approximately 20,000 genes, and it is scientifically impossible to detect pathogenic mutations in a person's genetic makeup if you don't know what you are looking for," the sperm bank further states.

But for biologist Edwige Kasper, the case primarily raises the question of the number of births allowed for each donor. According to the sperm bank, at least 67 children were conceived thanks to the donation of the man carrying the genetic mutation. The children were born in eight European countries between 2008 and 2015. According to the Guardian, the variant was detected in 23 children, 10 of whom were diagnosed with cancer. Today, the Danish sperm bank imposes a limit of 75 families per donor.

Edwige Kasper believes that this high ceiling "creates a risk of artificial dissemination of a genetic disease." "In normal life, it is extremely rare for a father to give birth to 75 children," she emphasizes.

Speaking to the Guardian, she called for the establishment of "a European limit on the number of births or families from a single donor." In France, "the number of children born from a single sperm donor is limited to 10 by bioethics law , to eliminate any risk of consanguinity for future generations," according to the website of the Biomedicine Agency. "My advice to French parents is to prefer medically assisted procreation in France," Edwige Kasper told Le Figaro.