WBR0107
| Author | PageAuthor::William J Gibson |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Genetics |
| Sub Category | SubCategory::Neurology |
| Prompt | [[Prompt::An eight year old boy is brought to the pediatrician by his mother. He complains that he has difficulty hearing his teacher. The patient denies pain, but his mother reports he seems to have decreased balance and complains of a ringing in his ears. MRI of the head reveal bilateral temporal opacities. What is the mode of inheritance of the most likely causal condition?]] |
| Answer A | AnswerA::Autosomal recessive |
| Answer A Explanation | AnswerAExp::Incorrect - Neurofibromatosis type 2 is autosomal dominant. An example of an autosomal recessive disease is Severe Combined Immunodeficiency. |
| Answer B | AnswerB::Autosomal dominant |
| Answer B Explanation | AnswerBExp::Correct - Neurofibromatosis type 2 is an autosomal dominant disease. |
| Answer C | AnswerC::X-linked recessive |
| Answer C Explanation | AnswerCExp::Incorrect - Neurofibromatosis type 2 is autosomal dominant. An example of an X-linked recessive disease is Duchenne muscular dystrophy. |
| Answer D | AnswerD::X-linked dominant |
| Answer D Explanation | AnswerDExp::Incorrect - Neurofibromatosis type 2 is autosomal dominant. An example of an X-linked recessive disease is Rett syndrome. |
| Answer E | AnswerE::Mitochondrial |
| Answer E Explanation | AnswerEExp::Incorrect - Neurofibromatosis type 2 is autosomal dominant. An example of an X-linked recessive disease is Myoclonic Epilepsy with Ragged Red Fibers. |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::The patient in this vignette has Neurofibromatosis Type II. The main manifestation of the disease is the development of symmetric, non-malignant brain tumors in the region of the cranial nerve VIII. More than 90% of NFII patients suffer eye lesions. The most common alteration in NF II is the juvenile subcapsular cataract (opacity of the lens) in young people. NF II is caused by mutations of the NF2 gene which seems, to influence the form and movement of cells. The principal treatments consist of neurosurgical removal of the tumors and surgical treatment of the eye lesions.
Educational Objective: Neurofibromatosis type 2 is an autosomal dominant disease. References: First Aid 2012 page 90. Tags: #Genetics #Neurology |
| Approved | Approved::Yes |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |