The case has led to demands from doctors for stricter international regulations in the area. Ten of the children who were born have since been diagnosed with cancer.
The case was discovered in connection with two families contacting their fertility clinics after their children developed cancer linked to the unusual gene named TP53.
When the sperm donation took place in 2008, the link to cancer was not known. The unusual variant would not have been detected through normal screening methods, writes The Guardian.
After investigations around Europe, 46 families and 67 children have been tested. The gene variant was detected in 23 children, ten who have so far been diagnosed with, among other things, leukemia and non-Hodgkin's lymphoma.
