What is the prevalence of human leukocyte antigen (HLA) B27 in psoriasis?

Updated: Oct 30, 2018
  • Author: Anna Luisa Di Lorenzo, MBBCh; Chief Editor: Andrew A Dahl, MD, FACS  more...
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The prevalence of arthritis in patients with psoriasis is higher than that found in the general population. It occurs in about 5-42% of patients with psoriasis. HLA-B27 is associated with the pustular form of psoriasis, and the association of HLA-B27 in peripheral psoriatic arthritis is weak. In the presence of spondylitis associated with psoriasis, 60-70% of these cases are HLA-B27 positive.

The age of onset of psoriatic arthritis is usually in the third or fourth decade and occurs equally in both sexes.

Psoriasis precedes the onset of arthritis by months or years. The prognosis of psoriatic arthritis is more favorable than that of rheumatoid arthritis unless it is the severe destructive form called arthritis mutilans. The course of the disease is mild, intermittent, and affects only a few joints. The proximal interphalangeal joints and distal interphalangeal joints are commonly involved with characteristic sausage-shaped digits. Knees, hips, ankles, temporomandibular joints, and wrists are less frequently involved. Most patients have onychodystrophy, which includes onycholysis and ridging and pitting of nail beds. Twenty-five percent of patients develop a more severe symmetrical arthritis resembling rheumatoid arthritis. Twenty-three percent develop psoriatic spondylitis, which differs from that in ankylosing spondylitis because it is less progressive and debilitating.

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