WBR0089
| Author | [[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Biochemistry, MainCategory::Genetics |
| Sub Category | SubCategory::Neurology |
| Prompt | [[Prompt::A 46- year old man was brought to the emergency department by his son with complaints of jerky movements, progressive loss of memory and aggressiveness. His symptoms started 2 years ago and have progressively worsened over the years. His father and grandfather died of similar symptoms. The deficiency of which of the following caused his symptoms?]] |
| Answer A | AnswerA::Serotonin |
| Answer A Explanation | AnswerAExp::Serotonin is decreased in anxiety, depression and increased in Parkinson’s disease |
| Answer B | AnswerB::GABA |
| Answer B Explanation | AnswerBExp::GABA is a neurotransmitter deficient in Huntington disease. Also decreased is the neurotransmitter Ach |
| Answer C | AnswerC::Dopamine |
| Answer C Explanation | AnswerCExp::Dopamine is increased in schizophrenia, decreased in Parkinson’s disease and depression |
| Answer D | AnswerD::Glutamate |
| Answer D Explanation | AnswerDExp::Glutamate is used by the brain to synthesize GABA but the deficiency of it does not cause Huntington disease. Neuronal death in Huntington disease is through NMDA-R binding and glutamate toxicity |
| Answer E | AnswerE::Norepinephrine |
| Answer E Explanation | AnswerEExp::Norepinephrine is a neurotransmitter seen in anxiety where it is increased and in depression, it is decreased |
| Right Answer | RightAnswer::B |
| Explanation | [[Explanation::The patient in this vignette has Huntington’s disease. It is caused by deficiencies in the neurotransmitters GABA and Ach. Symptoms manifest in affected individuals between the ages of 20 and 50. It is a trinucleotide repeat disorder (CAG)n with the gene located on chromosome 4. Findings include depression, progressive dementia, choreiform movements, caudate atrophy and decreased levels of GABA and Ach in the brain Educational Objective: |
| Approved | Approved::Yes |
| Keyword | |
| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |