Hailey-Hailey disease is a genetic skin disease that causes blistering. Signs and symptoms include a painful rash and blistering in skin folds, such as the armpits, groin, neck, under the breasts, and between the buttocks. Secondary bacterial infections are not uncommon. Symptoms are often worse in summer months due to heat, sweating, and friction. Hailey-Hailey disease is caused by genetic changes in the ATP2C1 gene and is inherited in an autosomal dominant manner.