| Typical Onset | Typically adolescence or early adulthood (10–30 years) |
| Prognosis | Death typically occurs between ages 1 and 4 years, with a mean survival of 18.9 months for early infantile onset [@passage2023] |
| Type I (infantile) | <2% residual β-gal activity |
| Type II (late infantile/juvenile) | 2–10% residual activity |
| Type III (adult/chronic) | 5–15% residual activity [@gangliosidosis2024] |
| Initial signs | Hypotonia, poor feeding, failure to thrive, exaggerated startle response |
| Progressive features | Developmental arrest and regression, seizures, progressive spasticity, cortical blindness |
| Characteristic findings | Cherry-red macular spot (50% of cases), coarse facial features, frontal bossing, gingival hypertrophy, hepatosplenomegaly, skeletal dysostosis multiplex |
| Primary features | Progressive dystonia (often generalized), gait abnormalities, dysarthria |
| Cognitive | Mild to moderate cognitive decline, usually later in disease course |
| Other features | Corneal clouding in some patients, mild vertebral anomalies |
| Progression | Slowest of all subtypes, with survival into the 3rd through 5th decade [^16] |
| Databases | OMIMOrphanetClinicalTrialsPubMed |