Mononucleotide precedes dinucleotide repeat instability during colorectal tumour development in Lynch syndrome patients.

A progressive accumulation of genetic alterations underlies the adenoma-carcinoma sequence of colorectal cancer. This accumulation of mutations is driven by genetic instability, of which there are different types. Microsatellite instability (MSI) is the predominant type present in the tumours of Lynch syndrome patients and in a subset of sporadic tumours.