Question

Which gene is most commonly mutated in Lynch syndrome (hereditary non-polyposis colorectal cancer)?

• A. APC
• B. MLH1
• C. KRAS
• D. BRAF

Hint:

Lynch syndrome involves mismatch repair defects; universal screening of colorectal tumors recommended.

Answer 1

The Correct Option is B

Step 1: Understanding the question.
Lynch syndrome results from germline mutations in DNA mismatch repair genes.
Step 2: Analyzing the options.
(A) APC: Mutated in familial adenomatous polyposis.
(B) MLH1: Correct — Most frequent mutation in Lynch syndrome.
(C) KRAS: Common in sporadic colorectal cancers.
(D) BRAF: Associated with sporadic MSI-high cancers.
Step 3: Conclusion.
The correct answer is (B) MLH1, the most commonly mutated gene in Lynch syndrome.