Generalized pustular psoriasis (GPP) is a severe form of a skin disorder called psoriasis. GPP and other forms of psoriasis are caused by abnormal inflammation. Inflammation is a normal immune system response to injury and foreign invaders (such as bacteria). However, when inflammation is abnormal and uncontrolled, it can damage the body's tissues and organs. Individuals with GPP have repeated episodes in which large areas of skin become red and inflamed and develop small pus-filled blisters (pustules). The skin problems can be accompanied by fever, extreme tiredness (fatigue), muscle weakness, an increased number of white blood cells, and other signs of inflammation throughout the body (systemic inflammation). The inflammation problems subside and reappear often. Episodes can be triggered by infection, exposure to or withdrawal from certain medications, menstruation, or pregnancy, although the trigger is often unknown. GPP can be life-threatening if not treated.

Mutations in several genes, including IL36RN and CARD14, increase the risk of developing GPP. These two genes provide instructions for making proteins that play roles in regulating inflammation, particularly in the skin. The IL-36Ra protein, produced from the IL36RN gene, blocks the activity of specific proteins that trigger signaling pathways to promote skin inflammation. IL36RN gene mutations involved in GPP reduce the amount of IL-36Ra protein in the skin. Without control by IL-36Ra, signaling pathways that promote inflammation are overly active.

GPP is the rarest form of psoriasis. Although the worldwide prevalence of GPP is unknown, the condition is estimated to affect 2 per million people in Europe. It also occurs in approximately 0.6 per million people each year in Japan.

When associated with IL36RN gene mutations, risk of GPP is typically inherited in an autosomal recessive pattern, which means both copies of the gene in each cell have mutations. The parents of an individual with an autosomal recessive condition each carry one copy of the mutated gene.

Published Date: May 01, 2017
Published By: National Institutes of Health