PMS2 and Lynch syndrome: Somatic inactivation of MLH1 via biallelic hypermethylation of MLH1's promoter is observed in ∼15% of sporadic CRCs, and biallelic somatic mutations of MSH2, MLH1, PMS2, or MSH6 are the apparent cause for Lynch-like syndrome in 1%–2% of all patients with CRC (5).