The frequency of mutations in several genes, such as Kirsten rat sarcoma viral oncogene homolog (K-Ras), tumor protein p53 (TP53), and phosphatidylinositol-4,5-bisphosphate 3-kinase catalytic subunit alpha (PIK3CA), has been reported to vary depending on the macroscopic type of CRC. The gene discussed is PIK3CA; the disease is colorectal carcinoma.