RESEARCH - Defective genes linked to RA

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New mutant genes linked to rheumatoid arthritis

Tan Ee Lyn

HONG KONG

Sun May 9, 2010 1:17pm EDT

HONG KONG (Reuters) - A large study of European populations has

uncovered seven new clusters of defective genes which may be

responsible for rheumatoid arthritis, a painful and disabling disease

that affects mainly the joints.

The paper was published in Nature Genetics on Monday together with

findings of a separate study in Japan, which identified one of the

seven genetic clusters as possibly causing the chronic inflammatory

disease among Japanese.

" The findings leverage us to better understand the basic biology of

rheumatoid arthritis (RA), with the goals of developing new targets

for therapy and new biomarkers for diagnosis and prognosis, " wrote

research scientist Eli Ayumi Stahl at the Brigham and Women's Hospital

in Boston in the United States, who led the study on European

populations.

The study was also intended " to develop better genetic tests for RA

risk, especially in people already at risk (such as arthritis patients

or relatives of patients with autoimmune disorders), " Stahl told

Reuters.

RA affects about 1 percent of the world's population. Apart from the

joints, it may affect the skin, heart, lungs, kidneys and blood

vessels. Many end up with deformed hands and feet, resulting in loss

of functions and movement.

In the European study, Stahl and colleagues repeated six previous

studies involving 5,539 patients, analyzing their genes using the

latest technology. They shortlisted 34 genetic variants which they

considered most suspect in causing RA.

They then checked if those genetic defects were found in another batch

of 6,768 RA patients in Canada, North America, the Netherlands and

Britain. Ten of the 34 variants figured most prominently in this

replication phase.

" Ten of the 34 variants tested were validated in the replication phase

of our study. Three were previously implicated in RA, leaving the 7

new ones mentioned above, " Stahl wrote.

" This is more RA risk variants discovered in a single study than any

other study to date, underscoring the importance of large-scale

studies and the collaborations that enable them in order to make

progress in unraveling common, complex diseases. "

" Our results further suggest that many more RA risk variants remain to

be definitively identified, " Stahl added.

In the Japanese study, researchers led by Yuta Kochi at the RIKEN

Center for Genomic Medicine in Yokohama, Japan, analyzed genes of

7,039 RA patients and identified a common genetic mutant near the CCR6

gene.

The CCR6 gene was also identified in the European study.

http://www.reuters.com/article/idUSTRE6481R820100509

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