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Seven cases of a childhood-onset peripheral neuropathy due to homozygous or compound ,heterozygous mutations of the SLC52A2 gene  in 3 separate  kindreds are described. Impaired function of the gene product results in deficiency of the riboflavin transporter protein resulting in reduced intracellular uptake of riboflavin. The clinical consequences of riboflavin depletion are protean and vary from (1) an infantile onset of progressive weakness often leading to respiratory failure, (2) a slowly progressive, predominantly sensory neuropathy resembling Friedreich ataxia and (3) a slowly progressive ponto-bulbar palsy, often evidenced by tongue fasciculations (Brown-Vialetto-van Laere syndrome). Sensori-neural deafness and optic atrophy are common associations resulting in a form of the optico-acoustic neuropathy syndrome. Interference with mitochondrial fatty acid β-oxidation results in abnormal acyl-carnitine profiles. An unusual feature is the predilection for weakness preferentially to involve the upper limbs resulting in the “child-in-the-barrel” appearance. Rather characteristic electrophysiological and histopathological findings are seen. It is essential that clinicians recognise the unique early phenotypes of SLC52A2 mutations as this otherwise progressive neurodegenerative and ultimately fatal condition responds to treatment with riboflavin, especially when therapy is commenced early in the disease.

peripheral neuropathy; SLC52A2