While we find that SOX9 mutation is associated with increased survival in patients with metastatic CRC on univariate analysis (p = 0.049), we also know that SOX9 mutation is associated with MMR deficiency in a non-random way as the majority of SOX9 truncating mutations in MMR deficient CRC were not in mono- or di- nucleotide repeat areas. Here, SOX9 is linked to mismatch repair cancer syndrome 1.