['The effectiveness of biologics for psoriasis shows heterogeneity among patients. With pharmacogenetic markers, it might be possible to predict treatment response.', 'We aimed to test the association between genetic markers and the response to biologics in psoriasis (etanercept, adalimumab, ustekinumab) in a prospective cohort.', "We investigated the copy number variation in LCE3B and 3C genes, and eight single nucleotide polymorphisms (SNPs) in HLA-C*06, CD84, IL12b, IL23R, TRAF3IP2, ERAP1, IFIH1 and TNFAIP3. The decrease in Psoriasis Area and Severity Index (PASI) was calculated as ∆PASI (absolute PASI decrease compared with baseline) and PASI75 (proportion of patients with at least 75% improvement compared with baseline). Associations between genetic variants and treatment outcome were assessed using multivariable linear regression analysis (∆PASI corrected for baseline PASI, primary analysis), and Pearson's χ", 'We included 348 treatment episodes in 234 patients. Patients heterozygous (GA) for the SNP in CD84 (rs6427528) had a better ∆PASI response to etanercept after three months (p 0.025) than the homozygous reference group (GG). In addition, heterozygous patients (CT) of the IL12b variant showed a better response (∆PASI) to ustekinumab (p 0.017) than the reference group (CC). Patients homozygous (GG) for the SNP in TNFAIP3 showed a worse response (∆PASI) to ustekinumab (p 0.031) than the reference group (TT). The associations with ustekinumab resulting from primary analysis were not confirmed in the secondary (PASI75) analysis.'] Are polymorphisms in CD84 , IL12B and TNFAIP3 associated with response to biologics in patients with psoriasis?