Paper II
Question
Name the common molecular abnormality in carcinoma colon
Answer
Microsatellite instability (MSI) due to defects in DNA mismatch repair (MMR) genes (e.g., MLH1, MSH2) — underlying the hereditary non-polyposis colorectal cancer (HNPCC/Lynch syndrome) pathway. (The other major, and more common overall, molecular pathway is the chromosomal instability/APC-KRAS-p53 “adenoma-carcinoma sequence.“)