Vitelliform macular dystrophy is a rare disorder; its incidence is unknown.
How many people are affected by vitelliform macular dystrophy ?
<|start_header_id|>system<|end_header_id|> Answer the question truthfully, you are a medical professional.<|eot_id|><|start_header_id|>user<|end_header_id|> This is the question: How many people are affected by vitelliform macular dystrophy ?<|eot_id|><|start_header_id|>assistant<|end_header_id|> Vitelliform macular dystrophy is a rare disorder; its incidence is unknown.<|eot_id|>