Next generation sequencing by Ion Torrent platform, mostly performed before first line metastatic treatment (89.6% of samples) and in primary tumor samples (79.1%), detected overall 77.8% KRAS2–4/NRAS2–4/BRAF15 mut MCRC patients at molecular diagnostic criteria of target sequence coverage >500×cov and >1% mutant AF; specifically, KRAS2–4 66.7%, NRAS2–4 16.4%, BRAF15 7.5% mut MCRC patients. The gene discussed is KRAS; the disease is atrial fibrillation.