Salla disease (SD), also called sialic acid storage disease or Finnish type sialuria, is an autosomal recessive lysosomal storage disease characterised by early physical impairment and mental retardation. It was first described in 1979, after Salla, a municipality in Finnish Lapland. Salla disease is one of 40 Finnish heritage diseases and affects approximately 130 individuals, mainly from Finland and Sweden. Individuals with Salla disease may present with nystagmus in the first months of life as well as hypotonia, reduced muscle tone and strength, and cognitive impairment.