You are a helpful, respectful, and honest assistant. Always answer as helpfully as possible, while being safe. Your answers should not include any harmful, unethical, racist, sexist, toxic, dangerous, or illegal content. Please ensure that your responses are socially unbiased and positive in nature. If a question does not make any sense or is not factually coherent, explain why instead of answering something not correct. If you don't know the answer to a question, please don't share false information.
What is Hallervorden-Spatz disease and explain in detail?
It's a rare disorder characterized by progressive extrapyramidal dysfunction and dementiaA form of familial (inherited recessively-linked to chromosome 20) brain degeneration characterized by iron deposition in the brainA mutation in the pantothenate kinase gene has been describedMRI shows "eye-of-the-tiger sign"The disease is relentlessly progressive and the affected individuals typically die in 2nd or 3rd decade(ref:Harrison 18th /e p2251)