Through research and observation, many of these factors have been identified. The following table, from an article in Cutis, lists a few factors that have been observed as influential in the onset of GPP. Source: "Table II", "Pustular Psoriasis" Farber and Nall, 1993

Genetic factors
Although there are likely to be multiple genetic factors and environmental triggers, mutations causing defects in the IL-36RN, CARD14 and AP1S3 genes have been shown to cause GPP. Diagnosis
Classification
It is important to note that while there are different forms of GPP, they are not exclusive of each other. One can morph into another, or multiple forms can occur simultaneously. von Zumbusch acute generalized pustular psoriasis
Von Zumbusch psoriasis is named after the German dermatologist Leo Ritter von Zumbusch (1874–1940), son of Kaspar von Zumbusch, who described the first documented case of generalized pustular psoriasis in the early 1900s. See Case Report #1. Sometimes all or any of GPP is referred to as von Zumbusch psoriasis, but in the literature it is often distinguished as one specific form of GPP.Eugene M. Farber, MD and colleagues provide a description of von Zumbusch psoriasis in "Pustular Psoriasis", published in Cutis. They describe the pattern as having "waves of widespread or universally fiery redness". The affected areas are "painful and tender". Small sub-corneal pustules form, with sizes originally between 1 and 10 mm in diameter. These pustules may merge to form "yellow-green lakes of pus". The pustules dry out, and "Waves of scarlatiniform [resembling scarlet fever] peeling follow, removing the desiccating pustules".
Benzphetamine (brand name Didrex) is a substituted amphetamine used short-term along with a doctor-approved, reduced-calorie diet, exercise, and behavioral program for weight loss. It is prescribed for obesity to people who have been unable to lose weight through exercise and dieting alone. It is a prodrug to dextroamphetamine and dextromethamphetamine.Benzphetamine is an anorectic, primarily promoting weight loss through reduced appetite. It also slightly increases metabolism. Pharmacology
Benzphetamine is a sympathomimetic amine and is classified as an anorectic. The drugs main function is to reduce appetite, which in turn reduces caloric intake.Although the mechanism of action of the sympathomimetic appetite suppressants in the treatment of obesity is not fully known, these medications have pharmacological effects similar to those of amphetamines. Amphetamine and related sympathomimetic medications (such as benzphetamine) are thought to stimulate the release of norepinephrine and/or dopamine from storage sites in nerve terminals of the lateral hypothalamic feeding center, thereby producing a decrease in appetite. This release is mediated through the binding of benzphetamine to VMAT2 and inhibiting its function, causing a release of these neurotransmitters into the synaptic cleft through their reuptake transporters. Tachyphylaxis and tolerance have been demonstrated with all drugs of this class.Benzphetamine has a half-life of 4–6 hours. Contraindications
Benzphetamine is contraindicated in patients with advanced arteriosclerosis, symptomatic cardiovascular disease, moderate to severe hypertension, hyper-thyroidism, known hypersensitivity or idiosyncrasy to sympathomimetic amines, and glaucoma, or who have recently used a MAOI. Benzphetamine should not be given to patients who are in an agitated state or who have a history of drug abuse.