Cat Eye Syndrome is listed as a rare disease by the Office of Rare Diseases (ORD) of the National Institutes of Health (NIH). This means that Cat Eye Syndrome, or a subtype of Cat Eye Syndrome, affects less than 200,000 people in the US population. Source - National Institutes of Health (NIH) Ophanet, a consortium of European partners, currently defines a condition rare when it affects 1 person per 2,000. They list Cat Eye Syndrome as a rare disease. Source - Orphanet