A variant in a gene encoding a key regulator of the immune system increases the risk of multiple sclerosis, report two papers to be published in Nature Genetics. Multiple sclerosis is a chronic and debilitating autoimmune disease in which neurons of the central nervous system become demyelinated, resulting in progressive neurodegeneration.
Susceptibility to multiple sclerosis is known to be strongly influenced by genetic factors, but little progress has been made in identifying them. Jonathan Haines and colleagues examined variants in three genes suspected to have a role in the disease, and found that variants in one of these genes, IL7R, were consistently more common in individuals with multiple sclerosis than in healthy control subjects. Their results were confirmed in four independent studies involving individuals of European descent from the United States, the United Kingdom and Belgium. Jan Hillert and colleagues, studying a large collection of individuals from Denmark, Finland, Norway and Sweden, observed a similar association between variants in IL7R and multiple sclerosis risk.
IL7R is present on the surface of some cells and can also be found in the blood serum. The variant thought to be responsible for conferring increased disease risk results in lower levels of the surface-bound form of IL7R and higher levels of the serum form, report Haines and colleagues. This change in the relative levels of the two forms of IL7R may alter the activity of the immune system, rendering individuals who carry the risk variant more susceptible to developing the disease.
In a related paper, to be published at the same time in the New England Journal of Medicine,(DOI: 10.1056/NEJMoa073493) David Hafler and colleagues report results of a genome-wide association scan and follow-up replication study confirming the association between IL7R and multiple sclerosis risk in a large collection of samples from the US and UK.
Jonathan Haines (Vanderbilt University Medical Center, Nashville, TN, USA)
Margaret A. Pericak-Vance (University of Miami, FL, USA)
Jan Hillert (Karolinska Institutet, Stockholm, Sweden)
Abstracts available online:
Paper 1 Abstract.
Paper 2 Abstract.
(C) Nature Genetics press release.
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