London: British scientists have pin-pointed the genetic fault behind the motor neurone disease (MND), a discovery they say could soon lead to a simple blood test for the condition.

Hundreds of people suffer from "familial" MND, in which muscles waste away because the nerve cells controlling their movement stop working.

The progressive disease leads to worsening disability, and frequently paralysis. Half of the patients die within 14 months of diagnosis.

But, a cross-university team at Cardiff, Manchester and University College London has pin-pointed the genetic fault behind the inherited MND after finding patients in Finland shared the same genetic trait with a family in Gwent, Wales, reports said.

People with this form -- responsible for 40 per cent of such familial cases -- have thousands of copies of a section of DNA on the ninth chromosome, the researchers found.

Most people have only five to 10 copies. Huw Morris, a lecturer in neurology at Cardiff, said the genetic cause was similar to that of a related disease, called myotonic dystrophy, for which there was already a blood test.

He said, "There's an NHS blood test for that, so this should be reasonably straightforward. Certainly, there should be a blood test available within a few months."

"The NHS laboratory in Cardiff that we worked with is working on it now," he added.

Although there is no cure for MND, the test would enable patients to check whether or not they inherited the disease, and to prepare accordingly, the researchers added.