Hereditary coproporphyria (HCP)'s a form of hepatic porphyria associated with a deficiency of the enzyme coproporphyrinogen III oxidase. Hereditary coproporphyria (HCP)'s an autosomal dominant genetic disease that causes purple urine, photosensitivity, and attacks of abdominal pain. Symptoms vary from mild to severe and can be regulated with diet and triggered with drug use. Symptoms Symptoms include reddish-purple urine, acute neurological problems (typically episodic confusion and sensory c… (More on Coproporphyria)