Question

Which of the following genes is most commonly mutated in Lynch syndrome (hereditary non-polyposis colorectal cancer)?

• A. APC
• B. MLH1
• C. KRAS
• D. TP53

Hint:

Lynch syndrome: Mismatch repair genes (MLH1, MSH2, MSH6, PMS2); contrast with APC in polyposis syndromes.

Answer 1

The Correct Option is B

Step 1: Understanding the question.
The question asks for the most common genetic mutation in Lynch syndrome, involving DNA mismatch repair genes.
Step 2: Analyzing the options.
(A) APC: Associated with familial adenomatous polyposis.
(B) MLH1: Correct — MLH1 and MSH2 are the most commonly mutated, with MLH1 frequently cited as predominant.
(C) KRAS: Common in sporadic colorectal cancers.
(D) TP53: Involved in Li-Fraumeni syndrome and many cancers.
Step 3: Conclusion.
The correct answer is (B) MLH1, as it is one of the most common mutations in Lynch syndrome.