An analysis published in The Journal of Allergy and Clinical Immunology has revealed clinical and genetic differences between palmoplantar pustulosis psoriasis (PPP) and generalized pustular psoriasis (GPP).

The investigators sought to characterize the clinical and genetic features of pustular psoriasis via analysis of an extended patient cohort. Pustular psoriasis, which often manifests with coexisting psoriasis vulgaris (PV), can have an acute systemic presentation (ie, GPP) or a chronic localized presentation (ie, PPP or acrodermatitis continua of Hallopeau ([ACH]). The rarity of this disease has thwarted efforts to study genotype-phenotype correlations.

Of the 863 unrelated patients evaluated, 251 had GPP, 560 had PPP, 28 had ACH, and 24 had multiple diagnoses. Mutation screening was performed in 473 patients. PV concurrence was lowest in those with PPP (15.8%) compared with 54.4% in patients with GPP and 46.2% in patients with ACH (P <.0005 for both). In contrast, mean age of onset was youngest in the GPP group (31.0) compared with 43.7 in the PPP group and 51.8 in the ACH group (P <.0001 for both). The percentage of women was higher in the PPP group than in the GPP group (77.0% vs 62.5%, respectively; P =5.8×10-5). In addition, the prevalence of smokers was also higher in the PPP group than in the GPP group (79.8% vs 28.3%, respectively; P <10-15).

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Although AP1S3 alleles had a similar frequency across disease subtypes (ie, 0.03-0.05), IL36RN mutations were significantly less common in patients with PPP than in patients with GPP or ACH (0.03, 0.19, and 0.16, respectively; P =1.9×10-14 and P =.002, respectively). Of note, in all types of pustular psoriasis, IL36RN disease alleles had a significant dose-dependent effect on age of onset (P =.003).

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The investigators concluded that additional studies in this field are warranted in order to elucidate the genetic landscape of pustular psoriasis, facilitate its diagnosis, and enhance the understanding of the correlation between genotype and clinical phenotype.


Twelves S, Mostafa A, Dand N, et al. Clinical and genetic differences between pustular psoriasis subtypes [published online July 20, 2018]. J Allergy Clin Immunol.