It has been suggested that CRC tumours with MMR defects usually retain a wild-type TP53 [3], however the 4 samples in this cohort with the c.215 C > A TP53 mutation also carried mutations in the MSH2, MSH6 and/or MLH1 genes, suggesting a hypermutated phenotype [4]. The gene discussed is MLH1; the disease is colorectal carcinoma.