HLA-Cw6-positive and HLA-Cw6-negative patients with psoriasis vulgaris have distinct clinical features

Psoriasis is associated with HLA-Cw6, and Caucasians who carry this allele have about a 10-fold increased risk of developing psoriasis. We have HLA-C typed 369 patients with familial psoriasis and compared the clinical features of the patients carrying HLA-Cw6 against those carrying other HLA-C types. Some striking clinical differences were observed between the two groups. Patients who are Cw6 positive had a lower age at onset (p = 3 X 10(-7)). Cw6-positive women had an earlier disease onset than Cw6-positive men (p = 0.02), but such a difference was not observed for the Cw6-negative patients. The guttate-type onset of psoriasis was mostly confined to this group (p = 2 X 10(-4)) and persistent disseminated guttate-like papules were also predominantly observed in the Cw6-positive patients (p < 10(-4)). The Cw6-positive patients also had more extensive plaques on their arms, legs, and trunk (p = 0.001), more severe disease (p = 0.003), higher incidence of the Koebner's phenomenon (p = 0.005), reported more often that their psoriasis got worse during or after throat infections (p = 0.02), and more often a favorable response to sunlight (p = 0.008) In contrast, dystrophic nail changes were more common in the Cw6-negative patients (p = 0.002) and also psoriatic arthritis, although this was not significant (p = 0.135). It is concluded that patients with psoriasis have different clinical features depending on whether they are HLA-Cw6 positive or negative.