Salla disease, intermediate severe Salla disease, and infantile free sialic acid storage disease (ISSD) are neurodegenerative disorders resulting from increased lysosomal storage of free sialic acid. The mildest phenotype is Salla disease, which is characterized by normal appearance and neurologic findings at birth followed by slowly progressive neurologic deterioration resulting in mild to moderate psychomotor retardation, spasticity, athetosis, and epileptic seizures.
Last updated October 2024