A 16-year-old boy is noted to have mucocutaneous pigmented spots on the lips and buccal mucosa along with recurrent colicky abdominal pain. Endoscopy reveals multiple polyps throughout the gastrointestinal tract, and biopsy shows arborising smooth muscle cores covered by normal epithelium. Inheritance of this condition is through mutation of which gene?
- A APC
- B MLH1
- C STK11 (LKB1) ✓
- D MUTYH
Correct answer: C. STK11 (LKB1)
Explanation
Peutz-Jeghers syndrome is an autosomal dominant disorder caused by germline mutations in STK11 (LKB1), characterised by hamartomatous polyps with arborising smooth muscle and perioral pigmentation. Patients carry elevated lifetime risks of gastrointestinal, breast, pancreatic, ovarian, and testicular tumours, requiring surveillance. APC causes familial adenomatous polyposis, MUTYH its recessive variant, and MLH1 Lynch syndrome; none produce hamartomas or lip pigmentation.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.