A 16-year-old boy presents with recurrent intussusception. Examination reveals mucocutaneous pigmentation of the lips and buccal mucosa. Biopsy of a gastric polyp shows arborizing smooth muscle with overlying normal epithelium. Which gene mutation underlies this condition?
- A STK11 ✓
- B SMAD4
- C MUTYH
- D PTEN
Correct answer: A. STK11
Explanation
Peutz-Jeghers syndrome results from germline mutations in STK11 (LKB1), a serine-threonine kinase tumour suppressor. It produces hamartomatous polyps throughout the gastrointestinal tract with characteristic arborizing smooth muscle cores, plus mucocutaneous pigmentation, and carries elevated risks of gastrointestinal, breast, pancreatic, and gynaecological malignancies. SMAD4 causes juvenile polyposis, MUTYH causes recessive polyposis, and PTEN causes Cowden syndrome.
Reference: Robbins and Cotran Pathologic Basis of Disease, 10th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
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