Balschun et al. studied 20 patients with SP-CRC for mutations in KRAS, NRAS, PIK3CA, and BRAF. KRAS mutations were discordant between synchronous lesions in 6 patients: 3 patients had mutated versus wild-type KRAS, and 3 patients had disparate mutation types in the synchronous lesions. The gene discussed is PIK3CA; the disease is colorectal carcinoma.