APC and familial adenomatous polyposis 2: For instance, somatic mutations in the APC gene in MAP tumours involve almost exclusively G>T transversions, an observation that led to the discovery of the MAP syndrome.[10] Similarly, the most prevalent KRAS2 mutation in MAP tumours is a G>T transversion at codon 12 (c.34G>T), which was reported to be present in 64% of MAP carcinomas.[11] Such mutation is infrequent in sporadic CRCs, according to published consecutive series.[12]