Some motor neuron disease, dementia patients share genetic defects: Research

Washington [US], May 9 : Some people with motor neuron disease (MND) and frontotemporal dementia (FTD) have the same uncommon genetic disorders that cause other neurodegenerative illnesses, according to a new study.

Researchers from Macquarie University's MND Research Centre and The Walter and Eliza Hall Institute of Medical Research revealed flaws in the genomes of certain patients with sporadic MND and FTD.

MND causes the neurons, or motor nerves, that connect the brain and spinal cord to the muscles to die. These are the cells that regulate how we move, breathe, and swallow. The sickness progresses and finally kills.

FTD also causes the death of neurons in part of the brain, resulting in a range of progressive symptoms such as memory loss, unusual behaviour, personality changes and communication problems. It is the same form of dementia with which actor Bruce Willis was recently diagnosed, and unlike older-onset dementia, it tends to affect people under 65.

The majority of cases in both diseases - about 90 per cent in the case of MND and 60-70 per cent in FTD - are sporadic, with the rest occurring in families.

These gene defects, known as short tandem repeat expansions, are the cause of more than 20 neurodegenerative diseases including spinocerebellar ataxias and myotonic dystrophy. This Australian study has been the most comprehensive assessment of these gene defects in MND and FTD patients worldwide.

Macquarie University Postdoctoral Research Fellow Dr Lyndal Henden says the findings were a surprise.

"We found almost 18 per cent of sporadic MND and FTD patients carried a DNA repeat expansion thought to be involved in other degenerative diseases," she says.

"Finding this genetic connection between MND and FTD offers a fresh opportunity to uncover common risk factors for neuron death, and it will have implications for understanding both diseases."

Macquarie University Associate Professor Kelly Williams directed the study, and says the team suspected there could be some overlap with other diseases, but not to such an extent.

"This suggests shared risk factors among these diseases, shared mechsms that cause nerves to die - and perhaps shared therapeutic strategies in the future," she said.

"While the causes of sporadic MND and FTD remain unknown, this is an important step in a long-term effort to identify the risk factors for developing one of these diseases."