An international team of genetic researchers led by Prof Merlin Crossley from the University of New South Wales has found the third and final missing piece in the genetic puzzle of an unusual form of haemophilia, known as haemophilia B Leyden, more than two decades after the first two pieces were discovered. The discovery, published in the American Journal of Human Genetics, could help improve understanding of other other blood-clotting conditions such as thrombosis.