Health authorities across Europe have issued urgent guidance after the discovery that sperm from a Danish donor, carrying a rare genetic mutation linked to increased cancer risk, was used to conceive nearly 200 children worldwide.

The investigation, conducted by Denmark’s public broadcaster DR in collaboration with 13 other European media outlets, revealed that at least 197 children were born using sperm from an anonymous donor known as “Kjeld” before the genetic anomaly was identified.

The European Sperm Bank (EBS), one of the largest in the world, was alerted in April 2020 when a child conceived through the donor developed cancer and was found to carry the TP53 mutation. Subsequent testing of the donor’s sperm initially failed to detect this rare mutation.

Authorities warn that it cannot be ruled out that biological descendants of this donor may develop clinical symptoms related to Li-Fraumeni syndrome. As a precaution, the donor’s genetic material is now banned from future use, and fertility clinics are instructed to contact recipients who completed full assisted reproduction cycles using the donor’s sperm.

Parents are advised to provide medical updates on any born children and consider targeted genetic testing to determine if they carry the TP53 variant c.325T>A p.(Phe10911e). In Greece, 18 children have been born using this donor’s sperm.

Between 2006 and 2022, the donor’s sperm was distributed to 67 clinics across 14 countries, including 99 children born in Denmark alone. The mutation is extremely rare and only present in a fraction of the donor’s sperm, meaning not all children conceived carry the alteration, and the donor himself remains unaffected.

The case has raised broader questions about cross-border sperm donation regulations. While some countries cap the number of children per donor, there are no international limits, prompting the European Sperm Bank to now restrict each donor to a maximum of 75 families.