NEWS: Rheumatoid arthritis gene link proven

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Rheumatoid arthritis gene link proven

Monday, 4 July 2005, 4:30 pm

Press Release: University of Otago

4 July 2005

Rheumatoid arthritis gene link proven

The gene PTPN22 has been confirmed as one of the factors that cause

rheumatoid arthritis by University of Otago researchers.

“This is only the second gene in the past 25 years to be universally

accepted as a gene associated with the susceptibility for arthritis,”

Department of Biochemistry Senior Research Fellow Dr Tony Merriman

says.

The finding has just been published in the leading international

arthritis research journal Arthritis and Rheumatism.

The research was funded by the Health Research Council of New Zealand

and Arthritis New Zealand.

The gene was first identified last year as potentially being

instrumental in causing rheumatoid arthritis, and Dr Merriman’s study

is one of the first studies to replicate - and thus validate - the

original findings.

“The initial finding is only half the story. It’s only when that

finding has been replicated convincingly that the initial paper becomes

of more importance, and I am delighted that we have been able to do

that,” Dr Merriman says.

“This is the culmination of six years of collecting samples and I want

to thank the many hundreds of people with and without rheumatoid

arthritis from around New Zealand who generously gave DNA samples. The

New Zealand Rheumatology Research Network also played a critical role.”

The resultant DNA database will play an important role in replicating

other international findings and generating new findings, as a large

sample group is vital to ensure results are reliable.

Confirmation that the gene plays a definite role in rheumatoid

arthritis means research pharmacists can study the gene’s mechanism and

where its messages break down in order to develop drugs to correct the

defect.

“Previously we knew rheumatoid arthritis was an immune disease but the

immune system is so huge and complex it is difficult for researchers to

know where to look – or necessarily what was a cause and what was a

result of the disease. Now we have a real starting point for research

into treatment as we know that PTPN22 is a cause.”

PTPN22 plays an important role in limiting the activity of the immune

system’s soldier cells, T lymphocytes, which attack and destroy foreign

cells. In rheumatoid arthritis T lymphocytes get out of control and

initiate and drive the attack on the body’s own cells.

“So it would seem that the message to control the T lymphocytes and

stop attacking the joints becomes faulty,” Dr Merriman says.

- Rheumatoid arthritis is a debilitating autoimmune disease where the

body attacks itself in the joints, causing inflammation, stiffness and

pain. It affects one in 50 New Zealand adults.

- PTPN22, is also over-represented in people with Type 1 diabetes and

thyroiditis, providing extra evidence it is a causal factor in

autoimmune diseases generally.