Generalized pustular psoriasis: strategy for identification of psoriasis susceptibility gene

Generalized pustular psoriasis (GPP), which occurs in recurrent waves of fever and is followed by tiny sterile pustules, appears as an uncommon variant form of psoriasis. About 360 patients suffering from GPP have been registered, according to the data of the nationwide epidemiological survey conducted by the Research Committee for Rare and Intractable Skin Diseases, Ministry of Health, Labor and Welfare of Japan. This figure is extremely low, as compared with 30,000 patients with psoriasis vulgaris. At present, neither a precise mode of inheritance nor the molecular mechanism of GPP has been elucidated. Clinically etretinate may be the drug of first choice for GPP in Japan. However, etretinate is not the drug of choice in women of childbearing age and in children, since this drug is a potent teratogen. Thus an attempt to screen for disease genes should be conducted to provide both a more effective and a safer drug. In this review we discuss the genetic aspects of GPP in comparison with psoriasis vulgaris.