Donor with hidden cancer gene fathered nearly 200 children across 14 countries

Dubai: A major fertility scandal has erupted after a Danish sperm donor — who unknowingly carried a rare mutation linked to aggressive, early-onset cancers — fathered at least 197 children worldwide, according to an AFP report and a parallel investigation by BBC News.

The donor, who used the alias “Kjeld,” appeared healthy and passed all routine screening checks. But investigations found that a portion of his sperm carried a rare TP53 mutation associated with Li-Fraumeni syndrome, a condition that gives carriers up to a 90% lifetime risk of developing cancer — often in childhood.

According to AFP, the European Sperm Bank was first alerted in April 2020 when a child conceived through this donor was diagnosed with cancer and found to carry a TP53 mutation. The sperm bank tested a stored sample, but the mutation did not show up in that batch, and sales resumed.

Only in late 2023, after another child was diagnosed, did fresh testing reveal the mutation. By then, the donor’s sperm had been distributed for nearly 17 years, reaching 67 clinics in 14 countries, AFP reported.

What is the TP53 mutation?

It damages a gene that normally prevents cells from turning cancerous.

What condition does it cause?

Li-Fraumeni syndrome, which carries up to a 90% lifetime cancer risk.

High risk of childhood cancers

The BBC, part of a 14-country investigative network, reported that among the known cases:

23 children tested positive for the mutation

10 had already developed cancer

Some children developed multiple cancers

A few have died at very young ages

Doctors across Europe raised alarms earlier this year at the European Society of Human Genetics after spotting multiple unrelated children with the same rare mutation — all traced back to the same donor.

The European Sperm Bank told AFP and the BBC that the donor remains healthy because the mutation exists only in some sperm cells, not throughout his body.

This rare occurrence, known as mosaicism, means standard screening would not detect it — a fact the sperm bank emphasised.

Up to 20% of the donor’s sperm carried the defective TP53 gene, the BBC reported. Children conceived from those specific sperm cells now carry the mutation in every cell of their body.

The BBC interviewed families grappling with lifelong cancer surveillance, including annual full-body MRIs, brain scans, ultrasounds, and, in adulthood, possible preventive mastectomies for women.

One mother in France, whose daughter inherited the mutation, said she was told she had been given sperm that “wasn’t safe.”

Authorities in the UK have confirmed that a “very small number” of British women who travelled to Denmark for fertility treatment used this donor’s sperm and have now been informed.

While many countries cap the number of families per donor, no international limit exists. As a result, the donor fathered:

99 children in Denmark

At least 197 children globally

Possibly more, as not all countries provided data

Belgium, which permits 6 families per donor, saw 38 women conceive 53 children with this donor. Denmark introduced a 75-family cap only in 2022 — far too late for this case.

Experts interviewed by the BBC warned that global reliance on large sperm banks has created a regulatory vacuum, allowing one donor to father hundreds of children across borders.

Geneticists quoted by the BBC and AFP said that while no screening can catch every mutation, global rules on donor limits are urgently needed to prevent such large-scale fallout in future.