The Spectrum of Mild to Severe Psoriasis Vulgaris Is Defined by a Common Activation of IL-17 Pathway Genes, but with Key Differences in Immune Regulatory GenesMild versus severe psoriasis is often distinguished by clinical measures such as the extent of skin involvement or Psoriasis Area and Severity Index score, both of which use arbitrary boundaries. It is widely assumed that severe psoriasis involves higher levels of skin inflammation, but comparative molecular profiles of mild versus severe disease have not been performed. In this study, we used immunohistochemistry, reverse transcription PCR, and gene arrays to determine the phenotype of North American patients with mild psoriasis (n = 34, mean PASI score = 5.5) versus severe psoriasis (n = 23, mean PASI score = 23.2).
Molecular Phenotyping Small (Asian) versus Large (Western) Plaque Psoriasis Shows Common Activation of IL-17 Pathway Genes but Different Regulatory Gene SetsPsoriasis is present in all racial groups, but in varying frequencies and severity. Considering that small plaque psoriasis is specific to the Asian population and severe psoriasis is more predominant in the Western population, we defined Asian small and intermediate plaque psoriasis as psoriasis subtypes and compared their molecular signatures with the classic subtype of Western large plaque psoriasis. Two different characteristics of psoriatic spreading—vertical growth and radial expansion—were contrasted between subtypes, and genomic data were correlated to histologic and clinical measurements.