Genetic links to multiple sclerosis have been identified for the first time in 30 years.

Scientists have pinpointed mutant versions of two immune system genes that together increase the risk of developing the disease by up to 60%.

The findings are based on analysis of DNA samples from more than 20,000 MS patients and non-sufferers. They may be particularly significant in Scotland, which has the highest incidence of the disease in the world.

While they welcomed the development, charities and patients emphasised that it highlighted the need for much more research.

Mark Hazelwood, director of the Multiple Sclerosis Society Scotland, said: "It is particularly tantalising for Scotland as we have more people with MS here than anywhere else.

"We don't know why that is, but it must be something to do with genes and something in the environment.

"This is a significant piece in the jigsaw, but there is still a huge amount that we don't understand. This shows that progress can be made with good research, and flags up the need for more."

Around 10,500 people in Scotland have MS, which is a complex disorder causing the immune system to attack and destroy myelin, the fatty insulation around nerve fibres.

That can create "short circuits" in the body's electrical system, leading to symptoms ranging from mild muscle weakness to total paralysis.

Several genetic and environmental factors are thought to be involved, but the exact mechanisms are unknown.

Like many Scots with MS, Falkirk mother-of-two Marie Wotherspoon, 57, worries about the risk of passing on the condition to her children, who are now grown up.

She said: "I've had MS for more than 20 years now and I am the only one in my family with it. I would not like to think that my son or daughter would get it too, but I would really like to find out if they will.

"A lot of other people with MS are interested in finding out if their children could develop MS too."

The latest research involved two large genetic studies by several US teams working with scientists from Cambridge University.

They compared the DNA of people with and without MS, looking for small but crucial variations in the genetic code that occurred more often in sufferers.

They found that altered versions of two genes involved in immune system signalling, IL2R-alpha and IL7R-alpha, jointly increased the chances of developing MS by as much as 60%.

The last major genetic breakthrough came in the 1970s when scientists discovered an association between genes that play a role in the body recognising itself - failure to do so causes autoimmune diseases - and MS.

A variant of one of these genes, HLA-DRB1, is widely accepted as the strongest genetic risk factor for MS, boosting the likelihood of developing the disease by up to fourfold.

Scientists were unable to explore genetic links in more detail until 2003 with the publication of the human genome, the full blueprint of the genetic code.

The latest research has suggested a new avenue for future studies. The IL2R-alpha gene is thought to be involved in two other autoimmune diseases: type 1 diabetes and autoimmune thyroid disease.

Professor David Hafler, a researcher from Harvard Medical School and Brigham and Women's Hospital in Boston, Massachusetts, said: "Scientists are increasingly finding genetic links between autoimmune diseases that affect different tissues in the body, including type 1 diabetes and rheumatoid arthritis.

"This study will likely spur further research into the connection between these seemingly separate conditions."

The findings were reported simultaneously in the New England Journal of Medicine and Nature Genetics.

Of Mice and Man

 SCIENTISTS have reportedly used DNA from a Scottish family to create the world's first mentally ill mice to further schizophrenia research.

They are said to have modified the DNA of laboratory mice to mimic a mutant found in a Scots family with an exceptionally high incidence of the illness.

It is understood to be the first time that animals have been bred for research into psychological rather than physical conditions.

The mice have shown symptoms similar to those in humans with the illness, such as hyperactivity and depression.

Researchers now plan to study the mice further and test drugs on them to develop treatments for people with schizophrenia.

Takatoshi Hikida, a lead researcher at Johns Hopkins University in Baltimore in the US, was quoted yesterday as saying: "These mutant mice may provide an important tool for the study of the factors that underlie mental illnesses like schizophrenia."

Animal rights campaigners have accused the scientists of causing the mice mental suffering.