A 25-year-old presents with bilateral acoustic neuromas (vestibular schwannomas). Genetic testing confirms a germline mutation. Which tumor suppressor gene is mutated?

• A RB1 (retinoblastoma gene)
• B TP53 on chromosome 17p13
• C NF2 gene (merlin/schwannomin) on chromosome 22q12 ✓
• D APC gene on chromosome 5q21

Explanation

Bilateral vestibular schwannomas are the hallmark of Neurofibromatosis Type 2 (NF2), caused by mutation of the NF2 tumor suppressor gene on chromosome 22q12, which encodes merlin (schwannomin). Merlin is a cytoskeletal protein that inhibits cell proliferation. Loss of both alleles (two-hit hypothesis) leads to uncontrolled Schwann cell growth. NF2 criteria include bilateral acoustic neuromas OR first-degree relative with NF2 plus one acoustic neuroma.

Reference: Dhingra Diseases of Ear, Nose and Throat, 7th ed.

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.