Table 2.
Main features of CAFSA compared with known free sialic acid disorders
| CAFSA | Salla disease (Aula and Gahl, 2001) | ISSD (Lemyre et al., 1999) | Sialuria (Aula and Gahl, 2001) | |
|---|---|---|---|---|
| Age at onset | 10–24 years | Infancy to Childhood | 1st year of life | Infancy |
| Horizontal nystagmus | No | Common | Yes | No |
| Cerebellar ataxia | Yes | Yes | Yes | No |
| Pyramidal syndrome | No | Yes | ND | No |
| Cognitive abnormalities | Cognitive or behavioural decline | Psychomotor retardation | Psychomotor retardation (severe) | Psychomotor retardation (mild) |
| Peripheral neuropathy | Axonal > demyelinating | 50% (demyelinating) | ND | ND |
| Dysmorphism | No | Mild | Yes | Yes |
| Growth retardation | Possible | Yes | Yes | No |
| Signs of organ storage | No | No | Yes | Yes |
| Cerebral MRI | ||||
| Cerebellar atrophy | Mild to moderate | Moderate to severe | Severe | No |
| Thin corpus callosum | No | Yes | Yes | No |
| White matter abnormality | Hilus of dentate nucleus, peridentate white matter and periventricular | Diffuse hypomyelination | Diffuse hypomyelination | No |
| Free sialic acid elevation | ||||
| Urine | No | Common*(+) | Yes (++) | Yes (+++) |
| CSF | Yes | Yes | ND | ND |
| Fibroblasts | No | Yes (lysosomal) | Yes (lysosomal) | Yes (cytoplasmic) |
*Salla patients have been reported without sialuria (Mochel et al., Ann Neurol, in press). ISSD = Infantile free sialic storage disease; ND = not determined; + = mild; ++ = moderate; +++ = massive.