Indeed, PCH2 patients have a more severe clinical course (near absent development and choreic movements), and do not present with ophthalmologic abnormalities (glaucoma, megalocornea, optic atrophy, and retinopathy), hearing loss or facial dysmorphism, which are frequently found in CASK mutated patients. The gene discussed is CASK; the disease is Leber hereditary optic neuropathy.