Relative values of serum K17 levels ranged from 113.9 to 2118.9 (median: 453.8), 174.3 to 1180.9 (median: 558.8), and 111.4 to 665.6 (median: 306.2) in patients with psoriasis vulgaris, psoriatic arthritis, and healthy controls, respectively. The gene discussed is KRT17; the disease is psoriatic arthritis.