After a screening test failed to catch that a Danish sperm donor had the disease,he has potentially passed a severe genetic disorder to five children.
The donor transmitted the tumor-producing nerve disorder Neurofibromatosis type I, sometimes known as Von Recklinghausen's disease, to five babies he fathered, said the Copenhagen clinic where he gave sperm, Nordisk Cryobank.
"In the case of these five, we know that the disorder came from the donor," even though the disorder is not always transmitted by a person's parents, said the clinic's director general, Peter Bower.
"I can say that prior to October 2009, this donor has provided sperm to 10 countries inside and outside Europe," Bower told AFP, saying he could not release specifics about where and when the babies were born because of confidentiality rules.
Public broadcaster DR reported that the donor had fathered 43 children at 14 clinics.
Denmark's national health council said because of the cases it would begin limiting the use of sperm from a single donor to 12 pregnancies from October 1 and immediately stop using sperm from any donor suspected of having passed on a genetic disorder.
Neurofibromatosis type I has widely different effects on those who suffer from it. Symptoms can include beige patches on the skin, high blood pressure, bone deformity, scoliosis, learning difficulties and eye problems including tumours on the optic nerve.