A single sperm donor who carries a rare cancer-causing genetic mutation has fathered at least 197 children across 14 countries in Europe, according to a collaborative investigation by 14 European news groups.
According to their investigative report, some of the children have already died, and many others are expected to develop deadly cancers.
The man—Donor 7069, alias “Kjeld”—carries a rare mutation in the TP53 gene, which codes for a critical tumor suppressor called protein 53 or p53. This protein (which is a transcription factor) keeps cells from dividing uncontrollably, can activate DNA repair processes amid damage, and can trigger cell death when a cell is beyond repair. Many cancers are linked to mutations in p53.
When a p53 mutation is passed down in sperm (a germline mutation), it causes a rare autosomal dominant condition called Li Fraumeni syndrome, which greatly increases the risk of a variety of cancers in childhood and young adults. Those include cancers of the brain, blood, bone, soft tissue, adrenal glands, and breast, among others.
The estimated frequency of this type of mutation is between 1 in 5,000 and 1 in 20,000 .
According to the investigation, the man was unaffected by the condition, but the mutation was present in around 20 percent of his sperm.