At least nine children have been born with the trait, Neurofibromatosis type 1 (NF-1), The Copenhagen Post reported Monday.
Sperm from a single donor with the condition was used at 14 different fertility clinics. Some 43 children were conceived with the sperm and at least nine of those children have been diagnosed with the condition,
NF-1 creates non-cancerous lumps on the bodies of affected individuals. Severe forms can lead to learning difficulties, blindness and epilepsy.
The sperm bank Nordisk Cryobank has come under scrutiny because one of two children conceived from the donor in the six months between when the clinic was warned about the sperm and when the clinic withdrew the material has NF-1.
Anne Marie Vangsted of the country's health agency said Nordisk Cryobank could have prevented some of the illnesses if it had withdrawn the sperm immediately after receiving the first warning in June 2009.
Nordisk Cryobank Chief Executive Officer Peter Bower defended his company, saying the sperm bank didn't act immediately because its employees didn't believe the donor was responsible for passing on the disease.