MLH1 and Lynch syndrome: Although the majority of normal colon mucosa tested (69%) showed a significantly low frequency of methylation compared with matched tumor samples (P = 0.0019) (Table 2), extensive methylation was detected in the normal colon mucosa from six patients, including a patient with Lynch syndrome (N7; Figure 3) with a germline mutation in the MLH1 gene (Table 1) and five patients with sporadic CRC: two MSS tumors (N1, N29; Figure 3) and three MSI-H tumors (N4, N5, N22; Figure 3) with activating V600E BRAF somatic mutation associated with MLH1 epigenetic silencing (Table 1).