NGS is the gold standard for identifying somatic pathogenic variants in MMR genes; there remain challenges in working with formalin-fixed paraffin-embedded tumor samples, but performance of NGS on such samples is improving.28 It should be noted that exon panel NGS will not identify MLH1 silencing due to methylation.29 Sequencing of PMS2 is problematic due to the presence of numerous pseudogenes.30 NGS is expensive and many hospitals have limited access to it. The gene discussed is MLH1; the disease is neoplasm.