SYDNEY, March 28 (Xinhua) -- A team of Australian scientists have helped solve the 40-year-old genetic mystery behind a rare and debilitating genetic muscle disorder known as Myoglobinopathy.

Prof. Nigel Laing and Prof. Alistair Forrest from the Harry Perkins Institute of Medical Research in Perth, assisting colleagues in Spain and Sweden, revealed on Wednesday that they had identified a mutation of the myoglobin gene as being the cause of the disorder.

"The late onset muscle disease causes muscle weakness and difficulty walking from about age 40, with wheelchair dependency occurring around 15 years later, it can also cause heart failure and breathing difficulties," Laing explained.

"We don't know how many people around the world suffer from Myoglobinopathy, but now the genetic mutation has been identified, it will be possible to test for it."

World renowned neuropathologist Prof. Montse Olivé, initiated the study after she linked two Spanish families with symptoms of the disease, with a Swedish family from a case 40 years ago in 1980.

The Harry Perkins Institute team was brought into the investigation because of their experience and reputation for finding the genetic causes of rare muscle diseases.

"We analysed the DNA of those two families and we found exactly the same mutation in their myoglobin gene," Olivé said.

"This is the first time that a disease caused by a mutation of the myoglobin gene has been identified."

Myoglobin is the protein that holds on to oxygen in our muscles and heart, and releases it when necessary, during movement or exercise.