Clinical and laboratory diagnosis of Salla disease in infancy and childhood.

Salla disease is an autosomal recessive lysosomal storage disorder; increased amounts of free sialic acid (N-acetylneuraminic acid) are found in urine and tissues. The disease causes severe psychomotor retardation, with onset by 1 year of age, but the patients have an apparently normal life-span. This paper describes the clinical features of Salla disease in six infants and young children and provides the background for laboratory diagnosis by thin-layer chromatography or spectrophotometric determination of sialic acid in urine.