Six Danish donor-conceived children remain untested for cancer-linked genetic mutation

A leading clinical geneticist has warned that critical health alerts may still not have reached all families affected by a sperm donor carrying a high-risk cancer mutation, despite two and a half years of notifications, Danish broadcaster DR reports.

Thirty-eight of the 44 Danish children conceived using sperm from the donor—identified by the alias “Kjeld”—have undergone genetic screening, according to a new tally from the Danish Patient Safety Authority. The remaining six have not been tested, raising concerns among specialists that their families may never have received or acted on warnings about the mutation, which significantly increases cancer risk.

“Then I must worry that the message hasn’t reached these families,” said Karin Wadt, professor and chief physician in clinical genetics at Copenhagen’s Rigshospitalet. The mutation, inherited by an estimated 10–20% of the donor’s biological children, carries a “very high risk of developing cancer,” she explained. Without awareness of the risk, diagnoses often come late, when tumors are advanced and prognoses poorer.

Early detection through genetic testing allows for preventive measures, including regular screenings and—for female carriers—prophylactic mastectomies around age 20 to reduce breast cancer risk. Yet without testing, Wadt noted, “you only find out whether they’ve inherited it if they’re genetically examined.”

The Danish Patient Safety Authority initially stated last month that all affected families had been contacted by fertility clinics, as required by law after the donor’s sperm was blocked in 2023 following multiple cancer cases among his offspring. However, the authority reversed its assessment after DR’s findings, acknowledging that while clinics may have sent notifications, not all mothers confirmed receipt or followed through with testing.

“We’re doing everything we can to ensure mothers are reinformed if their children haven’t been evaluated,” said Bente Møller, unit manager at the authority. Clinics are not obligated to request confirmation of receipt, and mothers face no legal requirement to respond or pursue testing.

Wadt dismissed suggestions that families might have consciously declined testing. “I find it hard to believe that anyone receiving this letter would choose not to seek genetic counseling to understand what it means,” she said.

The mutation, linked to donor 7069 (alias Kjeld), can trigger cancers even in childhood. European geneticists first raised alarms in May 2025 after confirming multiple deaths among the donor’s offspring and questioning whether all at-risk children had been identified.