A 24-year-old man comes to the physician with complaints of tinnitus, vertigo, and hearing loss. A contrast-enhanced, T1-weighted image of his brain is shown below. This patient's condition is most likely associated with a mutation involving which of the following genes?

Question

A 24-year-old man comes to the physician with complaints of tinnitus, vertigo, and hearing loss.  A contrast-enhanced, T1-weighted image of his brain is shown below.  This patient's condition is most likely associated with a mutation involving which of the following genes?

Quizplus · Accepted Answer

11ec160b_39d5_ffaa_9249_3f46f803eb4b_MD0001_00 11ec160b_39d5_ffab_9249_3b6a7fe454c1_MD0001_00 The MRI image above shows bilateral tumors at the cerebellopontine angle. Most intracranial schwannomas are found at the cerebellopontine angle and are attached to CN VIII. Schwannomas at this location are called acoustic neuromas. Tinnitus, vertigo, and hearing loss are the typical symptoms of an acoustic neuroma. Bilateral acoustic neuromas occur in neurofibromatosis (NF) type 2. NF-2 differs from NF-1 in that it causes fewer cutaneous manifestations and presents with central nervous system involvement. Both types of neurofibromatosis are autosomal dominant conditions, although they occur due to mutations on different chromosomes. The difference between these 2 diseases is summarized below. (Choice A) Mutation of the APC gene (adenomatous polyposis coli) on chromosome 5 is associated with familial adenomatous polyposis syndromes and colon cancer. (Choice B) Mutation of the NF-1 gene on chromosome 17 leads to NF-1. It is characterized by café-au-lait spots, Lisch nodules, and multiple neurofibromas. Bilateral acoustic neuromas are not characteristic of NF-1. (Choice D) Mutation of p53 (the tumor suppressor gene on chromosome 17) is the most common mutation found in human cancers. It is also associated with Li-Fraumeni syndrome, a rare familial syndrome characterized by the development of breast cancer, sarcomas, brain tumors, leukemia, and adrenocortical tumors at a young age. (Choice E) Mutation of the RB1 tumor suppressor gene on chromosome 13 increases the risk of retinoblastoma and osteosarcoma. (Choice F) Mutation of the VHL gene on chromosome 3 occurs in von Hippel-Lindau disease. It is characterized by renal cysts, renal cell carcinomas, and hemangioblastomas of the cerebellum and retina. Educational objective: Bilateral acoustic neuromas are associated with neurofibromatosis type 2, an autosomal dominant condition caused by mutation of the NF-2 gene on chromosome 22.

A 24-Year-Old Man Comes to the Physician with Complaints of Tinnitus