Metabolic mysteries: GI bleeding, gallbladder polyps and evolving developmental delay

Dr JP Stevens shares the mystery of a 5-year-old boy presenting with severe gastrointestinal bleeding and cholestasis. Inpatient investigation reveals gallbladder polyps and, on assessment after recovery he is found to have signs of developmental delay. Can you recognise the clues in the presentation? https://onlinelibrary.wiley.com/doi/10.1097/PG9.0000000000000122