At least 197 children were fathered by sperm donor with cancer-causing gene. Some have already died.

(CNN) — A sperm donor with a rare genetic mutation linked to an increased risk of developing cancer fathered at least 197 children across Europe, some of whom have already died from the disease, according to a new investigation.

The donor, who is himself healthy, had a rare mutation in a gene named TP53, which is likely to cause Li-Fraumeni syndrome, a rare disorder that increases a person’s risk of developing cancer. He was unaware when he made the sperm donations that he was affected by the mutation.

In May, CNN reported that the man had fathered at least 67 children in eight European countries, but a major investigation published by news outlets Wednesday has shown that the number of affected children is in fact far higher than previously thought.

According to the BBC, which is one o