Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0004134 (ataxia)
 15,886 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Brown-Vialetto-Van Laere syndrome (BVVLS) is a rare degenerative neurological disorder characterized by pontobulbar palsy and sensorineural deafness. Since its initial description in 1894, fewer than 100 cases have been reported, and published neuropathological analyses of these cases are extremely rare. Recently, individuals with BVVLS have been found to carry mutations in the C20orf54 gene, which encodes the human homolog for a rat riboflavin transporter. We present the case of a male who presented at the age of 5 years with sensorineural deafness, as well as those of 2 infant sisters who presented at 11 and 13 months of age with weakness and ataxia, respectively. All cases were genetically confirmed. We include the 1st immunohistochemical characterization of C20orf54 expression in BVVLS and controls. Results showed punctate axonal staining in the control cases that was dramatically reduced in the 3 BVVLS cases compared to the 5 controls. This decreased staining was seen even in the neocortex, which was unaffected in the BVVLS cases by routine histology. While the implications of these results are far from definitive, and although the evaluation of more cases is needed, immunohistochemistry for the C20orf54 protein may eventually be useful, in the right clinical scenario, as a screening test when selecting cases for sequencing of the C20orf54 gene to diagnose BVVLS at autopsy.
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PMID:Brown-Vialetto-Van Laere syndrome: clinical and neuropathologic findings with immunohistochemistry for C20orf54 in three affected patients. 2368 82

Childhood onset motor neuron diseases or neuronopathies are a clinically heterogeneous group of disorders. A particularly severe subgroup first described in 1894, and subsequently called Brown-Vialetto-Van Laere syndrome, is characterized by progressive pontobulbar palsy, sensorineural hearing loss and respiratory insufficiency. There has been no treatment for this progressive neurodegenerative disorder, which leads to respiratory failure and usually death during childhood. We recently reported the identification of SLC52A2, encoding riboflavin transporter RFVT2, as a new causative gene for Brown-Vialetto-Van Laere syndrome. We used both exome and Sanger sequencing to identify SLC52A2 mutations in patients presenting with cranial neuropathies and sensorimotor neuropathy with or without respiratory insufficiency. We undertook clinical, neurophysiological and biochemical characterization of patients with mutations in SLC52A2, functionally analysed the most prevalent mutations and initiated a regimen of high-dose oral riboflavin. We identified 18 patients from 13 families with compound heterozygous or homozygous mutations in SLC52A2. Affected individuals share a core phenotype of rapidly progressive axonal sensorimotor neuropathy (manifesting with sensory ataxia, severe weakness of the upper limbs and axial muscles with distinctly preserved strength of the lower limbs), hearing loss, optic atrophy and respiratory insufficiency. We demonstrate that SLC52A2 mutations cause reduced riboflavin uptake and reduced riboflavin transporter protein expression, and we report the response to high-dose oral riboflavin therapy in patients with SLC52A2 mutations, including significant and sustained clinical and biochemical improvements in two patients and preliminary clinical response data in 13 patients with associated biochemical improvements in 10 patients. The clinical and biochemical responses of this SLC52A2-specific cohort suggest that riboflavin supplementation can ameliorate the progression of this neurodegenerative condition, particularly when initiated soon after the onset of symptoms.
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PMID:Treatable childhood neuronopathy caused by mutations in riboflavin transporter RFVT2. 2442 12

Brown-Vialetto-Van Laere syndrome is a rare disorder characterized by motor, sensory, and cranial neuronopathies, associated with mutations in SLC52A2 and SLC52A3 genes that code for human riboflavin transporters RFVT2 and RFVT3, respectively. The authors describe the clinical course of a 6-year-old girl with Brown-Vialetto-Van Laere syndrome and a novel homozygous mutation c.1156T>C in the SLC52A3 gene, who presented at the age of 2.5 years with progressive brain stem dysfunction including ptosis, facial weakness, hearing loss, dysphagia, anarthria with bilateral vocal cord paralysis, and ataxic gait. She subsequently developed respiratory failure requiring tracheostomy and worsening dysphagia necessitating a gastrostomy. Following riboflavin supplementation, resolution of facial diplegia and ataxia, improvements in ptosis, and bulbar function including vocalization and respiration were noted. However, her sensorineural hearing loss remained unchanged. Similar to other cases of Brown-Vialetto-Van Laere syndrome, our patient responded favorably to early riboflavin supplementation with significant but not complete neurologic recovery.
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PMID:A Case of Brown-Vialetto-Van Laere Syndrome Due To a Novel Mutation in SLC52A3 Gene: Clinical Course and Response to Riboflavin. 2885 73

Brown-Vialetto-Van Laere syndrome represents a phenotypic spectrum of motor, sensory, and cranial nerve neuropathy, often with ataxia, optic atrophy and respiratory problems leading to ventilator-dependence. Loss-of-function mutations in two riboflavin transporter genes, SLC52A2 and SLC52A3, have recently been linked to Brown-Vialetto-Van Laere syndrome. However, the genetic frequency, neuropathology and downstream consequences of riboflavin transporter mutations are unclear. By screening a large cohort of 132 patients with early-onset severe sensory, motor and cranial nerve neuropathy we confirmed the strong genetic link between riboflavin transporter mutations and Brown-Vialetto-Van Laere syndrome, identifying 22 pathogenic mutations in SLC52A2 and SLC52A3, 14 of which were novel. Brain and spinal cord neuropathological examination of two cases with SLC52A3 mutations showed classical symmetrical brainstem lesions resembling pathology seen in mitochondrial disease, including severe neuronal loss in the lower cranial nerve nuclei, anterior horns and corresponding nerves, atrophy of the spinothalamic and spinocerebellar tracts and posterior column-medial lemniscus pathways. Mitochondrial dysfunction has previously been implicated in an array of neurodegenerative disorders. Since riboflavin metabolites are critical components of the mitochondrial electron transport chain, we hypothesized that reduced riboflavin transport would result in impaired mitochondrial activity, and confirmed this using in vitro and in vivo models. Electron transport chain complex I and complex II activity were decreased in SLC52A2 patient fibroblasts, while global knockdown of the single Drosophila melanogaster riboflavin transporter homologue revealed reduced levels of riboflavin, downstream metabolites, and electron transport chain complex I activity. This in turn led to abnormal mitochondrial membrane potential, respiratory chain activity and morphology. Riboflavin transporter knockdown in Drosophila also resulted in severely impaired locomotor activity and reduced lifespan, mirroring patient pathology, and these phenotypes could be partially rescued using a novel esterified derivative of riboflavin. Our findings expand the genetic, clinical and neuropathological features of Brown-Vialetto-Van Laere syndrome, implicate mitochondrial dysfunction as a downstream consequence of riboflavin transporter gene defects, and validate riboflavin esters as a potential therapeutic strategy.
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PMID:Clinical, pathological and functional characterization of riboflavin-responsive neuropathy. 2905 33