ISTANBUL 

A sperm donor carrying a rare genetic mutation that increases cancer risk fathered at least 197 children across Europe, and some of them have already died from the disease, according to a new investigation.

The donor, who was unaware he carried a rare TP53 mutation linked to Li-Fraumeni syndrome, remained healthy himself despite the disorder’s high cancer risk.

The donor gave samples to Denmark’s European Sperm Bank (ESB), but his sperm was ultimately used by 67 clinics in 14 countries, and the number of affected children may be higher, as not all countries have provided data, the BBC reported on Wednesday.

ESB acknowledged that the donor’s sperm was overused and expressed its “deepest sympathy” to the families affected.

The bank said the mutation could not have been detected through screening and that it “immediately blocked” the donor once the issue came to light.

The investigation found that children conceived with the donor’s sperm were born in Denmark, Belgium, Spain, Greece, and Germany, while the samples were also sent to Ireland, Poland, Albania, and Kosovo and used in fertility treatments for women from Sweden.

While only up to 20% of the donor’s sperm carry the harmful TP53 mutation, absent from most of his body, any child conceived from those affected sperm inherits the mutation in every cell, and only a minority who inherit the mutation will escape cancer in their lifetimes.

Li-Fraumeni syndrome carries up to a 90% lifetime risk of developing cancer, including childhood cancers and breast cancer later in life.