A sperm donor who unknowingly carried a gene variant that can cause cancers fathered nearly 200 children across Europe, some of whom have already died, according to an investigation published Wednesday by a group of 14 European news organizations.
The man started donating sperm at Denmark’s European Sperm Bank in 2005, which was sold to women from at least a dozen countries over roughly 17 years, the organizations reported. He is healthy and had passed the donor screening checks, but some of his cells had a mutation in a gene called TP53, the healthy version of which helps prevent the body’s cells from turning malignant. Donor checks don’t often look for rare mutations.
Most of the man’s cells do not have the mutation, but up to 20% of the sperm he makes do. Any child born from sperm with the mutation would have the mutation in all of their cells, causing what’s known as Li-Fraumeni syndrome. People born with the condition have a roughly 90% chance of developing at least one type of cancer by age 60, and half develop cancer by age 40. Many get cancer during childhood.
The news organizations found that the donor fathered at least 197 children, though the true number could be higher. It’s not known how many of the children inherited the mutated form of TP53. The TP53 gene encodes a protein called p53, which is one of the body’s most important tools to prevent cells from becoming cancerous.
The investigation was conducted by groups including the BBC, DW, and the Danish Broadcasting Corporation, as part of the European Broadcasting Union’s Investigative Journalism Network.
The European Sperm Bank said it extended its “deepest sympathy” to families affected, according to the news organizations. It said the mutation is “not detected preventatively by genetic screening.” The clinic stopped selling the man’s sperm in 2023 once the mutation was discovered.
The investigation captured the wide impact of the problem. The sperm was shipped to fertility clinics in Iceland, Ireland, Spain, Germany, and other countries. And while the man’s sperm was not sold to clinics in the U.K., for example, some British families who had fertility treatment in Denmark used the sperm, the BBC reported.
While no law dictates how many times a donor’s sperm can be used globally, some countries set their own maximums. In this case, those limits were sometimes broken, the news organizations reported. In Belgium, for example, 38 women had 53 children with sperm from the donor, even though sperm from one donor is only supposed to be sold to six families in the country.
The sperm bank said that the limits had “unfortunately” been surpassed and that it was talking with authorities in Denmark and Belgium.
Patients with Li-Fraumeni have to undergo frequent cancer screening to try to detect any tumors early. The issue was first flagged by doctors who had seen children with cancer who had been born via a sperm donation.
Experts told the news organizations that fertility clinics have become increasingly reliant on large sperm banks that ship supplies internationally. Some experts have also called for global limits on how many times sperm from one donor can be used.