Colorectal cancer (CRC) is one of the most important causes of morbidity and 
mortality in the developed world and is gradually more frequent in the 
developing world including Saudi Arabia. According to the Saudi Cancer Registry 
report 2015, CRC is the most common cancer in men (14.9%) and the second most 
prevalent cancer. Oncogenic mutations in the KRAS gene play a central role in 
tumorigenesis and are mutated in 30-40% of all CRC patients. To explore the 
prevalence of KRAS gene mutations in the Saudi population, we collected 80 CRC 
tumor tissues and sequenced the KRAS gene using automated sequencing 
technologies. The chromatograms presented mutations in 26 patients (32.5%) in 
four different codons, that is, 12, 13, 17, and 31. Most of the mutations were 
identified in codon 12 in 16 patients (61.5% of all mutations). We identified a 
novel mutation c.51 G>A in codon 17, where serine was substituted by arginine 
(S17R) in four patients. We also identified a very rare mutation, c.91 G>A, in 
which glutamic acid was replaced by lysine (E31K) in three patients. In 
conclusion, our findings further the knowledge about KRAS mutations in different 
ethnic groups is indispensable to fully understand their role in the development 
and progression of CRC.