Combination of polymorphism and antibodies associated with highly increased risk of rheumatoid arthritis

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Combination of polymorphism and antibodies associated with highly

increased risk of rheumatoid arthritis

People who have a specific genetic variant of the PTPN22 gene and

test positive for antibodies against cyclic citrullinated peptide are

much more at risk of developing rheumatoid arthritis than people who

only have one of these markers.

A study published today in the journal Arthritis Research & Therapy

reveals that a group of people who have a specific genetic variant,

or polymorphism, of PTPN22, a gene that encodes a tyrosine

phosphatase protein, and tested positive for anti-cyclic

citrullinated peptide (CCP) antibodies, all developed rheumatoid

arthritis (RA) in the following two and a half years. Both the

polymorphism and anti-CCP antibodies have previously been shown to be

associated with RA, but in combination they give a much higher risk

of developing the disease than separately. This combination gives a

much higher relative risk than the combination of anti-CCP antibodies

and the previously well-known genetic factor, namely HLA DR4 antigens.

Johansson and colleagues from the University Hospital in Umea,

Sweden studied a population of 92 patients diagnosed with RA for whom

a blood sample was available, which had been taken on average about

two and a half years before the onset of the disease. They were

matched with controls - blood donors from the same group who didn’t

develop arthritis - for age, sex, and rural or urban residence.

The presence of the PTPN22 1858T polymorphism was determined by

genotyping and anti-CCP antibodies were detected by immunoassay of

the blood samples taken two and a half years before onset of the

disease.

Johansson et al.’s results confirm previous findings that RA patients

are more likely to have the PTPN22 1858T polymorphism than controls.

Individuals with the PTPN22 1858T polymorphism were more likely to be

positive for anti-CCP antibodies, but none of the controls with the

polymorphism were positive for anti-CCP antibodies. All of the blood

donors who had anti-CCP antibodies and have the PTPN22 1858T

polymorphism had developed RA an average of two and a half years

after the blood sample was taken.

http://www.innovations-report.com/html/reports/medicine_health/

report-53312.html