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Pathogenesis of psoriatic arthritis

Dafna D Gladman, MD, FRCPC
Christopher Ritchlin, MD, MPH
Section Editor
Joachim Sieper, MD
Deputy Editor
Paul L Romain, MD


The precise causes of psoriasis and psoriatic arthritis (PsA) have not been identified. It seems likely, however, that genetic, immunologic, and environmental factors all contribute [1]. It is also reasonable to assume that the skin and joint diseases have a similar pathogenesis, although the activity of these manifestations does not highly correlate in individual patients. (See "Clinical manifestations and diagnosis of psoriatic arthritis".)


Psoriasis has long been known to occur in families. The possible role of genetic factors is illustrated by the following observations [2-5]:

Approximately 40 percent of patients with psoriasis or psoriatic arthritis (PsA) have a family history of these disorders in first-degree relatives [6].

Family studies in PsA have demonstrated that the disease is 55 times more likely to occur among first-degree relatives than among unrelated controls [7]. A significantly increased risk of PsA among first-degree relatives of patients with PsA has also been described [8]. The concordance rate for PsA is much higher than that for psoriasis (30 versus 7 percent) [9].

There is greater concordance for psoriasis among monozygotic twins than among dizygotic twins [10]. One study of twin pairs with at least one patient with PsA found a similar rate of concordance for PsA in monozygotic and dizygotic twins, arguing against a strong role for a heritable component for PsA, but the results in this relatively small study were imprecise and not conclusive [10].

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Literature review current through: Nov 2017. | This topic last updated: Jul 05, 2016.
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