12th May 2024

A 7-year-old boy presents with persistent diarrhoea, abdominal distension, and failure to thrive.

A 7-year-old boy presents with persistent diarrhoea, abdominal distension, and failure to thrive. His mother reports that his symptoms seem to worsen after meals, particularly after eating bread or pasta. Physical examination reveals a distended abdomen and reduced muscle mass. Blood tests show iron-deficiency anaemia and low vitamin D levels. A small bowel biopsy is suggestive of villous atrophy.

Which underlying mechanism is most likely responsible for his clinical presentation?