Molecular Genetics and Immunopathogenesis of Psoriasis


Psoriasis (OMIM #177900) is a common chronic disease of the skin that affects approximately 2–3% of the population. Typical lesions of psoriasis are characterised by red and scaly skin patches, usually found on the scalp, elbows and knees and often associated with severe arthritis. These lesions are caused by abnormal keratinocyte proliferation and infiltration of inflammatory cells into the dermis and epidermis. The onset of the disease is generally between 10 and 40 years of age. Type 1 begins at or before the age of 40 years; type II begins after the age of 40 years. Psoriasis is a complex disease due to the interaction between environmental factors and susceptibility alleles. Life style, diet, smoking, stress and infections are the best validated environmental factors predisposing to the pathology. During the past several years, researchers have identified different loci related to the disease, namely from PSORS1 to PSORS13.

Key Concepts:

  • Multifactorial diseases are common disease due to the interaction between environmental factors and different susceptibility loci.

  • Psoriasis, a chronic disease of the skin, is a common disease affecting approximately 2–3% of the population.

  • Psoriasis is a complex disease. Different loci are known to be responsible for its development, together with some environmental factors, such us life style, diet, smoking, stress and infections.

  • Immune system is responsible for the development of psoriasis: HLACw*06:02 is the best replicated and validated susceptibility allele.

  • Understanding the genetic and epigenetic basis of psoriasis will help to further outline the molecular mechanism of onset and progression.

Keywords: complex diseases; psoriasis; psoriasis genetics; susceptibility loci; immunopathogenesis

Figure 1.

Evolution of Psoriatic Lesion.



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Further Reading

Asumalahti K, Laitinen T, Lahermo P et al. (2003) Psoriasis susceptibility locus on 18p revealed by genome scan in Finnish families not associated with PSORS1. Journal of Investigative Dermatology 121: 735–740.

Kauffman CL, Aria N, Toichi E et al. (2004) A phase I study evaluating the safety, pharmacokinetics, and clinical response of a human IL‐12p40 antibody in subjects with plaque psoriasis. Journal of Investigative Dermatology 123: 1037–1044.

Tsunemi Y, Saeki H, Nakamura K et al. (2002) Interleukin‐12 p40 gene (IL12B) 3‐prime‐untranslated region polymorphism is associated with susceptibility to atopic dermatitis and psoriasis vulgaris. Journal of Dermatological Science 30: 161–166.

Zhang XJ, He PP, Wang ZX et al. (2002) Evidence for a major psoriasis susceptibility locus at 6p21 (PSORS1) and a novel candidate region at 4q31 by genome‐wide scan in Chinese Hans. Journal of Investigative Dermatology 119: 1361–1366.

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Lepre, Tiziana, Zampatti, Stefania, Novelli, Giuseppe, and Giardina, Emiliano(Sep 2012) Molecular Genetics and Immunopathogenesis of Psoriasis. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0022477]