This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Retina, Subject name: Ophthalmology
Retinitis pigmentosa is a feature of all except: 
Select and explain. 
A. Refsum's disease, B. Hallervorden-Spatz disease, C. NARP, D. Abetalipoproteinemia
B: Hallervorden-Spatz disease
Answer: B: Hallervorden-Spatz disease 
Explanation: Now Hallervorden Spatz doesn't have RP as a feature. Remember RP associations by mnemonic LUCHR. *Lawrence moon Beidel syndrome *Usher *Cockayne *Hallgren *Refsum Other associations: NARP, Abetalipoproteinemia