A new intermediate severe Salla disease patient with hypomyelination: a literature review for Salla disease

Publication date: Available online 1 June 2017
Source:Pediatric Neurology
Author(s): Rebecca Barmherzig, Garrett Bullivant, Dawn Cordeiro, David S. Sinasac, Susan Blaser, Saadet Mercimek-Mahmutoglu
BackgroundLikely pathogenic variants in SLC17A5 results in allelic disorders of free sialic acid metabolism including 1) infantile free sialic acid storage disease with severe global developmental delay (GDD), coarse facial features, hepatosplenomegaly and cardiomegaly; 2) intermediate severe Salla disease with moderate to severe GDD, hypotonia, hypomyelination with or without coarse facial features, and 3) Salla disease with normal appearance, mild cognitive dysfunction and spasticity.Case Report and resultsThis five-year-old girl presented with infantile onset severe GDD, truncal hypotonia and generalized dystonia following a normal development in the first six months of life. Brain MRI showed marked hypomyelination and thin corpus callosum at age 19 months, both unchanged on follow-up at 28 months of age. Urine free sialic acid was moderately elevated. Cerebrospinal fluid (CSF) free sialic acid was also marginally elevated. Sequencing of SLC17A5 revealed compound heterozygous likely pathogenic variants: a known missense (c.291G>A) variant and a novel truncating (c.819+1G>A) variant, confirming the diagnosis of Salla disease at the age of 3.5 years.ConclusionWe report a new patient with intermediate severe Salla disease. Normal or marginally elevated urine or CSF free sialic acid levels cannot exclude Salla disease. In patients with progressive GDD and hypomyelination on brain MRI, Salla disease should be included into the differential diagnosis.



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