20th July 2023

A 27-year-old man presents to his GP with a 2-month history of epigastric pain

A 27-year-old man presents to his GP with a 2-month history of epigastric pain that is worse at night and often relieved with eating. He reports 1 episode of haematemesis 2 weeks ago. He has a history of a right-sided renal stone 4 years ago that was managed conservatively. He takes no regular medications and is allergic to ciprofloxacin. He was conceived by IVF and is an only child. His mother has also suffered from recurrent renal stones. Clinical examination is unremarkable apart from 8 3-5mm skin-coloured papules, some with overlying blood vessels. Formal bloods reveal a normocytic anaemia, normal renal and liver function, normal inflammatory markers, a mildly raised calcium with raised parathyroid hormone levels. Due to his haematemesis, he undergoes an upper GI endoscopy which reveals 2 peptic ulcers in the duodenum.

Given the most likely diagnosis, which gene mutation would be most likely in this patient?

Select the SINGLE most appropriate option from the list below. Select ONE option only.