Familial Aggregation in Psoriatic Arthritis: Phenotypic Differences in Patients With and Without a Family History of Psoriatic Disease

Objective Although up to 45% of patients with psoriatic arthritis (PsA) have a family history of psoriatic disease, it is unclear whether this family history contributes to a distinct PsA phenotype and/or the timing of disease onset. We aimed to identify differences in onset, domain involvement, and disease activity based on family history of psoriatic disease. Methods A total of 843 patients with PsA were enrolled in an observational, longitudinal registry. Demographics, medical history, family history, and psoriatic phenotype and activity were collected. Results Of the total, 379 patients (45.0%) had at least one first‐degree relative (FDR) or second‐degree relative (SDR) with psoriatic disease. Those with a family history developed psoriasis and PsA earlier than those with no family history (psoriasis: mean 27.6 vs 32.2 years [ P < 0.01]; PsA: mean 37.6 years vs 40.3 years [ P < 0.01]) and were more likely to have entheseal involvement (36.7% vs 30.0%; P < 0.05). Patients with an FDR or SDR with PsA were diagnosed with psoriasis and PsA earlier than those with an FDR or SDR with psoriasis alone, followed by those with no family history (psoriasis: mean 26.3 vs 27.8 vs 32.2 years, respectively [ P < 0.01]; PsA: mean 36.5 vs 37.9 vs 40.3 years, respectively [ P = 0.01]). Conclusion In this cohort, patients with PsA with a family history of psoriatic disease were diagnosed with psoriasis and PsA earlier and were more likely to have entheseal involvement compared to those without a family history. Further research incorporating molecular and immune features is needed to investigate genetic, environmental, and epigenetic factors that impact PsA phenotype and severity, as well as the transition from psoriasis to PsA.