Martin 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.
PTPN22 polymorphism and anti-CCP antibodies in combination strongly predicts future onset of rheumatoid arthritis and has a specificity of 100% for the disease.
Martin Johansson, MSc, Lisbeth Ärlestig, MSc, Göran Hallmans MD, PhD and Solbritt Rantapää-Dahlqvist, MD, PhD
Arthritis Research & Therapy 2006, 8:R19 (22 December 2005)