Since MSI was clearly evident and no MMR mutations were detected by panel-base comprehensive tumour profiling it is likely, but not proven, that either epigenetic modification resulting in the loss of expression of one of the MMR genes (most likely MLH1) has occurred or there is deletion not identified (for example between EPCAM and MSH2) that results in the silencing of MSH2 [12]. The gene discussed is MSH2; the disease is neoplasm.