An infant of Ashkenazi Jewish descent presents at 3 months with lethargy, listlessness, weak cry, poor head control, and hypotonia. He doesn't move his extremities very much. His general pediatrician isn't sure what is going on, and the infant is simply observed. At 5 months, it's clear he has macrocephaly, and at 6 months, he develops spasticity, hyperreflexia, extensor plantar responses, and tonic extensor spasms. By the time he reaches your clinic, he's developed blindness and seizures. The pediatric ophthalmologist diagnoses optic atrophy. His CSF is normal. A T2-weighted MRI is shown below:
Challenge: What's your diagnosis?
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