Canadian researchers have pinpointed the genetic cause of a bleeding disorder known as Quebec Platelet Disorder (QPD).

The disorder, which causes blood to thin rather than clot, can lead to uncontrolled bleeding after something as simple as routine dental work or massive swelling after bruising. It affects one in 150,000 people and is treated with medication.

Scientists at McMaster University in Hamilton, Ont., have discovered that Quebec Platelet Disorder is the result of a gene mutation that causes the overproduction of an enzyme that converts blood platelets into clot busters. The condition has been traced to one Quebec family.

"This is novel as QPD is the very first bleeding disorder attributed to having an extra copy of a gene, rather than a defective copy," McMaster University hematologist Dr. Catherine Hayward said in a release.

The abnormal gene can be passed to children by just one parent. By identifying it early, researchers can now test infants for the disorder and begin treatment immediately if necessary.

'Key to proper treatment'

"The types of mutation that causes some bleeding problems are mistakes that are likely to happen again, and typically, they cause a protein to become defective or deficient," said Hayward.

"The family needed to know whether this child would need life-long monitoring, and treatments to counteract their clot busting platelets, as having a definite yes or no answer early is key to proper treatment."

The McMaster scientist worked with investigators at the Hospital for Sick Children in Toronto and the University of Montreal. They studied 38 people afflicted with the disorder and 114 persons from the family who did not have QPD.

The findings were published in the journal Blood on Feb. 11.