ALAS1 and infection: AIP is an autosomal dominant disorder with a very low penetrance rate, <10% of patients have recurrent acute attacks, but acute attacks are often life-threatening.[28] There are 2 types of AIP, usually the activity of HMBS in mutation carriers is about 50% of that in normal subjects, and there are no symptoms at this time, which is called the latent type; when metabolic stress, infection, smoking and drinking induce an increase in the activity of ALAS1, the rate-limiting enzyme of heme synthesis, the clinical symptoms are induced,[28,29] which is called the dominant type.