Salla disease is the mildest form of the free sialic acid storage disorders, which primarily affect the nervous system. Infants with Salla disease typically begin to experience poor muscle tone (hypotonia) during the first year of life,followed by slowly progressive neurological problems. Signs and symptoms include intellectual disability and developmental delay; seizures ; ataxia ; muscle spasticity; and involuntary slow movements of the limbs (athetosis). About one-third of affected children learn to walk. It is caused by mutations in the SLC17A5 gene and is inherited in an autosomal recessive manner. Treatment is generally symptomatic and supportive. The disease is Salla disease (MONDO_0011449, a Monarch Disease Ontology term). Also known as: sialic acid storage disease.