APC and Familial adenomatous polyposis: FAP arises from mutations in the tumour-suppressing adenomatous polyposis coli (APC) gene, located on chromosome 5q.3 4 APC encodes a 312 kDa multifunctional protein crucial for the degradation of β-catenin, thereby negatively regulating the Wnt signalling pathway involved in cell proliferation, apoptosis and tissue homeostasis.3