Adult-onset ornithine transcarbamylase deficiency as a rare cause of fatal hyperammonaemia

A 27-year-old man presented to an emergency department with vomiting and an altered mental state. He had a history of possible Gilbert's syndrome as a child and previous opiate use disorder, but with no evidence of recent use. He gave a family history of a maternal grandfather who had developed seizures during a hospital admission for asthma. The patient had otherwise been fit and well and physically active—including playing hockey. While in the...