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Free sialic acid storage disease without sialuria
Fanny Mochel1, Bingzhi Yang, Julie Barritault
1Institut National de la Sante et de la Recherche Médicale UMR S679, Hôpital La Salpêtrière, Paris, France. fanny.mochel@baylorhealth.edu
Annals of Neurology
|June 27, 2009
Summary
Mutations in the SLC17A5 gene can cause hypomyelination and mental retardation, even without sialuria (abnormal sialic acid in urine). This highlights the importance of considering SLC17A5 gene mutations in diagnosing such neurological disorders.
Area of Science:
- Biochemistry
- Genetics
- Neurology
Background:
- Leukodystrophies are a group of rare genetic disorders affecting myelin in the brain.
- Diagnosing leukodystrophies of unknown cause requires comprehensive metabolic and genetic analysis.
- Free sialic acid storage diseases are a group of metabolic disorders characterized by the accumulation of free sialic acid.
Observation:
- High-resolution proton nuclear magnetic resonance spectroscopy was used on cerebrospinal fluid and urine from 44 patients with undiagnosed leukodystrophies.
- Two siblings presented with mental retardation and mild hypomyelination, showing elevated free sialic acid in cerebrospinal fluid.
- Urinary free sialic acid levels were normal in these siblings, despite repeated testing by two independent methods.
Findings:
- The affected siblings were homozygous for the K136E mutation in the SLC17A5 gene.
- Mutations in SLC17A5 are known to cause free sialic acid storage diseases.
- This study identifies a novel presentation of SLC17A5 mutations where sialuria is absent.
Implications:
- Mutations in the SLC17A5 gene should be considered in the differential diagnosis of hypomyelination and intellectual disability, even when urinary screening for sialic acid is negative.
- This expands the phenotypic spectrum of SLC17A5-related disorders.
- Understanding these genetic underpinnings can lead to improved diagnostic strategies and potential therapeutic interventions for leukodystrophies.
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