Cause of brain disease found

Gene cause of brain disorder identified

The gene which causes a fatal childhood disease has been identified by scientists.

Alexander disease affects children, usually boys, in their first year. Most do not survive beyond the age of six.

The condition is extremely rare, with the American scientists who carried out the research only able to identify 13 cases over two years from all over the world on which to base their research.

The scientist leading the research said although a cure was a long way off, pinpointing the cause would offer comfort to parents of children affected by the condition.

Brain disorder

Alexander disease is part of a family of disorders called leukodystrophies, in which abnormalities develop in the protective layer covering the nerves, called the myelin sheath.

Children who develop the condition fail to grow normally and do not develop physical, mental or behavioural skills at the expected times.

Other symptoms can include enlargement of the head, dementia, seizures and spasticity, the stiffening of the arms and legs.

It tends to occur randomly, with no family history and there is no cure for the condition and no standard course of treatment.

Chance discovery

Experts had always believed Alexander disease had a genetic cause, but it was the work of Albee Messing and his team at the University of Wisconsin-Madison which identified the specific gene.

I think parents who have had children with Alexander disease will be relieved by finally knowing its cause

Albee Messing
Researcher

They stumbled on it while carrying out different research.

A genetically engineered mouse by chance showed the key symptoms of Alexander disease, which enabled the scientists to more easily identify the gene responsible.

Mutations in the gene are associated with nearly all cases of the condition, say the scientists.

Protein build-up

The mutation causes an abnormal protein to be created, causing the build-up of fibres which damage the nervous system.

A build-up of protein which damages nerve function has also been identified as part of the development of Alzheimer's and Parkinson's disease, but Dr Messing said scientists did not know if the build-up was a by-product or a cause of the diseases, or if it could be treated.

He added that identifying the cause of Alexander disease would have been "a shot in the dark" without the team's initial discovery. Dr Messing said the research could eventually lead to treatments, but added that this would be well in the future.

"I think parents who have had children with Alexander disease will be relieved by finally knowing its cause. It's such a rare disorder that they have felt very isolated, thinking that no-one was working to find answers."

The research is published in Nature Genetics.