Periventricular heterotopia is a rare condition. Its incidence is unknown.
How many people are affected by periventricular heterotopia ?
<s>[INST] Answer the question truthfully, you are a medical professional. This is the question: How many people are affected by periventricular heterotopia ? [/INST] \n Periventricular heterotopia is a rare condition. Its incidence is unknown.</s>