Dozens of children conceived with sperm from cancer gene carrier, Belgian authorities confirm

Fifty-two children were conceived in Belgium between 2008 and 2017 using sperm from a Danish donor who carries a rare genetic mutation associated with a high risk of early-onset cancer, Belgian health authorities confirmed.

According to reporting by Le Soir and The Guardian, the donor passed on a mutation of the TP53 gene, which causes Li-Fraumeni Syndrome—a hereditary condition that significantly increases the likelihood of developing cancer, including leukemia and lymphoma, from a young age.

The donor, known only as “X”, fathered at least 67 children across Europe, 52 of whom were conceived through assisted reproduction in Belgium across 12 fertility clinics. At least 10 of those children have since developed cancer, the British newspaper reported.

Belgium’s Health Minister described the situation as a “double trauma” for families—stemming both from the real genetic threat and the revelation that their children were conceived using sperm from a donor widely used across Europe.

The donor had initially been temporarily suspended by the European Sperm Bank (ESB) in April 2020 after one of the children developed cancer. A genetic test at the time did not detect the TP53 mutation, and the donor was reinstated. It wasn’t until October 2023, during a new round of testing, that the ESB permanently banned the donor and issued alerts to fertility clinics.

The mutation was unknown to be linked to disease at the time of the original donation, the ESB said, and the donor was healthy with no known family history of cancer. The lack of early detection tools meant the mutation was not screened for.

The case involves 37 families in Belgium and elsewhere. According to Belgium’s Federal Agency for Medicines and Health Products, alerts have been issued since April 2024 to trace affected children, with additional warnings sent through the EU’s vigilance system later in the year.

Countries potentially impacted include Bulgaria, Cyprus, Germany, Spain, Hungary, Ireland, Greece, the Netherlands, and Poland.

The incident has exposed significant regulatory shortcomings in Belgium’s sperm donation monitoring system. Despite a 2007 law limiting a donor’s use to six women, authorities acknowledged the rule was not enforced due to a lack of oversight tools.

By comparison, France caps donor offspring at 10, the UK at 12, and Germany and Denmark at 15. The European Sperm Bank, however, had allowed up to 75 children per donor.