Word: ms
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...went into a hyperalert state to begin with. Was it caused by a virus? Was it nutritional, as suggested by a study last week in the journal Neurology, which found that having too little vitamin D, normally produced in the body during exposure to sunlight, increases the risk of MS? Or, were genes to blame for inciting the immune system to rebel? Or, was it, as most experts believe, some combination of all of the above...
...better answer, leading MS scientists in the U.S., including Hafler, teamed up with researchers in England and formed the International Multiple Sclerosis Genetics Consortium in 2002. The plan was to take their genetic study to the next level. So, they pooled their resources and examined the entire genomes of more than 2,000 MS sufferers, their families and control subjects. "People had been studying the genetics of MS for 20 years, and nothing had come out of it," says Hafler. "I felt we needed a genetic roadmap to show us what pathways to study that would help to explain...
What they found were two new genes, IL2 and IL7, which code for receptors for interleukin - the proteins that regulate how T cells work in the body. People with certain forms of these genes have a 20% increased risk of developing MS. It is not, however, a defective or mutated form of the genes that causes MS; rather, it's certain forms of the genes, known as variants, that increase risk. The etiology of MS is complicated and appears to involve many genes, so the next challenge will be to figure out precisely what role these two new genetic variants...
...exciting as the discovery is, it's a small part of the story: the new genes account for less than 1% of the risk of developing MS. In addition, about 70% of the normal, non-MS affected population has the same variants. "Every single time we have looked for genes for MS, the genes turn out to have a very small effect," says Dr. Moses Rodriguez, professor of immunology at the Mayo Clinic and a leading MS researcher." That suggests that either the disease is not genetically controlled in a significant way, or that if it is, that there...
Hafler acknowledges that these findings are only the first step. Uncovering additional genes will require analyzing an even larger pool of MS patients and their families - Hafler is hoping to find at least 9,000 more patients. He calculates that with that much DNA, he'll be able to tease out 90% of the genetic culprits involved in MS. "These first genes give us a working hypothesis for what may be causing MS," says Hafler, "and a lot more work needs to be done. But we have finally begun...