Arthritis & Rheumatism, Volume 62,
November 2010 Abstract Supplement

Abstracts of the American College of
Rheumatology/Association of Rheumatology Health Professionals
Annual Scientific Meeting
Atlanta, Georgia November 6-11, 2010.


HLA- B27 and Cw06 Are Risk Alleles for Psoriatic Arthritis among Psoriasis Patients.

Eder2,  Lihi, Pellett2,  Fawnda, Chandran2,  Vinod, Shanmugarajah2,  Sutha, Gladman1,  Dafna D.

Toronto Western Hospital, Toronto, ON, Canada
Toronto Western Hospital, Centre for Prognosis Studies in the Rheumatic Diseases, Toronto, ON, Canada

Aim:

Genes that differentiate patients with Psoriatic Arthritis (PsA) from those with psoriasis alone serve as markers for the development of PsA in patients with psoriasis. We aimed to identify HLA alleles that are associated with PsA among psoriasis patients.

Methods:

In this population based association study, we performed HLA typing in 3 groups: PsA, psoriasis without arthritis and healthy controls. The PsA group included adult patients satisfying the CASPAR criteria that were part of a large prospective PsA cohort. The psoriasis patients were recruited from a recently established psoriasis cohort that was confirmed by a dermatologist. These patients were examined annually by a rheumatologist to rule out the presence of inflammatory arthritis. Control DNA was from healthy Caucasian volunteers, cadaveric organ donors from laboratories of the University Health Network and from a commercial biobank. Extracted genomic DNA was amplified by PCR using locus specific primers for each of the HLA-A, -B, -C, -DR and DQ loci. PCR amplicons were identified by Sequence Specific Oligonucleotide probes using a reverse line blot technique. Caucasian subjects from the PsA and psoriasis cohorts were combined into a "Psoriatic disease" group that was compared to the healthy controls. The differences in allelic distributions for each of the HLA loci were compared using chi square test and Fisher exact test. Bonferroni corrected p values were calculated to adjust for multiple testing. A logistic regression analysis was performed to account for the strong linkage disequilibrium between the HLA alleles.

Results:

804 PsA patients, 412 psoriasis patients without arthritis and 719 healthy controls were included in the study. The mean ages for the psoriasis, PsA and control subjects were: 45.7±13.1, 42.3±12.6 and 43.6±17.2 years respectively. The proportions of females were: 41.9%, 43.5% and 49.3% respectively. The following HLA alleles were found to be significantly different between the psoriatic disease group and healthy controls: A*03 (20% vs. 27.3%, Odds Ratio (OR) 0.6, p=0.05), B*07 (16.3% vs. 25.8%, OR 0.6, p= 4*10-4), B*13 (9.7% vs. 4.7%, OR 2.2, p=0.01), B*27 (14.1% vs. 7.2%, OR 2.1, 3*10-4), B*38 (11.9% vs. 2.5%, OR 5.3, p= 10-10), B*51 (5.7% vs. 10.7%, OR 0.5, p= 3*10-5), Cw*03 (15.9% vs. 22.5%, OR 0.7, p=0.05), Cw*06 (32.8% vs. 18.1%, OR2.2, p= 8*10-10), Cw*07 (44.2% vs. 56.6%, OR 0.61, p= 4*10-5), Cw*12 (19.4% vs 10.2%, OR 2.1, p= 2*10-5), DRB1*15 (19.2% vs. 26.5%, OR 0.7, p=0.03), DQB1*0602 (17% vs. 24.7%, OR 0.6, p=0.009). When the PsA group was compared to the psoriasis alone group the only HLA alleles that were found to be significantly different were: B*27 (17.7% vs. 4.1%, OR 5, p= 4*10-9), Cw*02 (11.6% vs. 4.8%, OR 2.7, p=0.01) and Cw*06 (26.9% vs. 42.1%, OR 0.5, p= 8*10-6). On logistic regression analysis only HLA B*27 (OR 4.6, 95% Confidence interval (CI) 2.5–8.3) and Cw*06 (OR 0.5, 95% CI 0.4–0.7) remained significantly associated with PsA compared to psoriasis.

Conclusions:

HLA*B27 is a risk allele for PsA among psoriasis patients, while HLA-Cw*06 is a protective allele.

To cite this abstract, please use the following information:
Eder, Lihi, Pellett, Fawnda, Chandran, Vinod, Shanmugarajah, Sutha, Gladman, Dafna D.; HLA- B27 and Cw06 Are Risk Alleles for Psoriatic Arthritis among Psoriasis Patients. [abstract]. Arthritis Rheum 2010;62 Suppl 10 :1974
DOI: 10.1002/art.29739

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