HEXB and Salla disease: In humans and Hexb-/- mice, which closely recapitulate features of SD, the disease manifests as a rapidly progressive neurodegenerative disorder characterized by extensive neuroinflammation followed by mass neuronal apoptosis, severe motor and developmental impairments, and death by age four in humans and 18–20 weeks in mice3,10,11 At present, there is no available curative or disease-modifying treatment for SD.