Researchers at the ANZAC Research Institute (University of Sydney and Concord Hospital) have found the cause of a hitherto mysterious disorder causing degeneration of motor nerves that leads to severe muscle wasting in the limbs.
The disease is manifest almost exclusively in men but inherited through their mothers as carriers, a pattern that arises because the disorder is linked to a gene on the X chromosome.
Affected men cannot run properly and show loss of strength in the hands and feet becoming increasingly disabled through later life. The gene defect causes a slow, but progressive degeneration of the ends of the long motor neurons which drive the limb muscles.
The research was carried out by studying patients with this disease which has similarities with disorders like Charcot-Marie-Tooth neuropathy. While the study was led by the ANZAC Institute’s group of Professor Garth Nicholson and Dr Marina Kennerson, the work also involved collaboration with research groups in Australia, Brazil, the USA, Switzerland and Belgium.
The discovery of the gene causing this disorder produced a big surprise because it turned out to be the same gene responsible for a completely different disease, a severe, infantile multisystem disorder of copper metabolism called Menkes (kinky hair) disease.
The researchers believe the gene abnormality they have discovered causes disease by impairing the body’s ability to control copper levels and this leads to damage in the ends of extremely long motor neuron cells.
This discovery raises the potential that treatments for this disease may eventually be found. The discovery was published in the most recent edition of the American Journal of Human Genetics. The research group is based at Concord Hospital and is run by Dr. M. Kennerson in association with Professor G. Nicholson, at the ANZAC Institute. The research has been supported by grants from the National Health and Medical Research Council and the Motor Neuron Disease Research Institute of Australia.