Porphyria, Acute Intermittent, also known as acute intermittent porphyria, is related to photoparoxysmal response 1 and toxic encephalopathy, and has symptoms including abdominal pain, constipation and diarrhea. An important gene associated with Porphyria, Acute Intermittent is HMBS (Hydroxymethylbilane Synthase), and among its related pathways/superpathways are Metabolism and Hemesynthesis defects and porphyrias. The drugs Midazolam and Omeprazole have been mentioned in the context of this disorder. Affiliated tissues include liver and skin, and related phenotypes are abdominal pain and elevated urinary delta-aminolevulinic acid