Brown Vialetto Van Laere syndrome, a fatal disease with a simple solution: a case series (original) (raw)
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Journal of Inherited Metabolic Disease, 2011
We report on three patients (two siblings and one unrelated) presenting in infancy with progressive muscle weakness and paralysis of the diaphragm. Metabolic studies revealed a profile of plasma acylcarnitines and urine organic acids suggestive of a mild form of the multiple acyl-CoA dehydrogenation defect (MADD, ethylmalonic/adipic acid syndrome). Subsequently, a profound flavin deficiency in spite of a normal dietary riboflavin intake was established in the plasma of all three children, suggesting a riboflavin transporter defect. Genetic analysis of these patients demonstrated mutations in the C20orf54 gene which encodes the human homolog of a rat riboflavin transporter. This gene was recently implicated in the Brown-Vialetto-Van Laere syndrome, a rare neurological disorder which may either present in infancy with neurological deterioration with hypotonia, respiratory insufficiency and early death, or later in life with deafness and progressive ponto-bulbar palsy. Supplementation of riboflavin rapidly improved the clinical symptoms as well as the biochemical abnormalities in our patients, demonstrating that high dose riboflavin is a potential treatment for the Brown-Vialetto-Van Laere syndrome as well as for the Fazio Londe syndrome which is considered to be the same disease entity without the deafness.
Neuropediatrics, 2012
Brown-Vialetto-Van Laere syndrome (Online Mendelian Inheritance in Man number 211530) is a neurodegenerative disorder characterized by pontobulbar palsy affecting cranial nerves (mainly VII-XII). Sensorineural deafness is often the leading sign, followed by other neurologic signs. Inheritance is often autosomal recessive, with mutations in the C20orf54 gene (Online Mendelian Inheritance in Man number 613350). Three previous patients with mutations in the C20orf54 gene and clinical signs of Brown-Vialetto-Van Laere or Fazio-Londe syndrome revealed a metabolic profile suggesting a multiple acyl-coenzyme A dehydrogenase defect. They benefited from riboflavin. We describe a 3-year-old girl with early-onset Brown-Vialetto-Van Laere syndrome and a novel mutation in the C20orf54 gene (c.989G>T). On T 2-weighted imaging, increased signal intensity of the vestibular nuclei bilaterally, the pedunculus cerebellaris superior and the central tegmental tract were observed during acute clinical deterioration. Her metabolic profile was normal. Trials with steroids, immunoglobulins, and riboflavin produced no effect. The patient recovered slowly during subsequent months, with residual deficits. Brown-Vialetto-Van Laere syndrome should be considered in patients with sensorineural hearing loss and pontobulbar palsy. Patients should be screened for riboflavin deficiency and a therapy with riboflavin may provide effective treatment in some affected patients.
Early use of high-dose riboflavin in a case of Brown-Vialetto-Van Laere syndrome
Developmental Medicine & Child Neurology, 2012
BVVLS Brown-Vialetto-Van Laere syndrome NIV Non-invasive ventilation Brown-Vialetto-Van Laere syndrome (BVVLS) is a genetic condition caused by a mutation in the C20orf54 gene, which also codes for an intestinal riboflavin transporter. We report the case of a female who presented at 22 months with acute-onset stridor and generalized muscle weakness, in whom a genetic diagnosis of BVVLS was made, and whose symptoms improved on therapy with high-dose riboflavin. She had previously been developing normally and was able to walk at 11 months, then developed progressive muscle weakness at 22 months, and within 2 weeks was unable to sit without support. She also demonstrated stridor and paradoxical breathing indicating diaphragmatic weakness, and required continuous non-invasive ventilation (NIV) through a tracheostomy. After treatment with riboflavin she was able to walk unaided, and her Gross Motor Functional Classification level improved from level IV to level I, having fully regained the motor function she showed before symptom onset. There were no longer signs of diaphragmatic paralysis while on NIV, and she was able to tolerate 10-minute periods off NIV before paradoxical breathing again became apparent. We therefore recommend that in all cases suspected to be in the BVVLS or Fazio-Londe spectrum, early treatment with high-dose riboflavin must be considered.
Genetic, Radiologic, and Clinical Variability in Brown-Vialetto-van Laere Syndrome
Seminars in Pediatric Neurology, 2017
Brown-Vialetto-van Laere (BVVL) syndrome is characterized by a progressive sensorimotor neuropathy, optic atrophy, hearing loss, bulbar dysfunction and respiratory insufficiency. Mutations in SLC52A2 and SLC52A3, encoding riboflavin transporters RFVT2 and RFVT3 respectively, are the genetic basis of this disorder, often referred to as riboflavin transporter deficiency types 2 and 3 respectively. We present cases of both types of riboflavin transporter deficiency, highlighting the distinguishing clinical features of a rapidly progressive motor or sensorimotor axonal neuropathy, optic atrophy, sensorineural hearing loss and bulbar dysfunction. One child presented with isolated central apnea and hypoventilation, not previously described in genetically confirmed BVVL, and later complicated by diaphragmatic paralysis secondary to phrenic nerve palsy. MR imaging showed T2-hyperintensity in the dorsal spinal cord in two children, as well as previously unreported cervical nerve root enlargement and cauda equina ventral nerve root enhancement in one child. Novel homozygous mutations were identified in each genea NM_024531.4(SLC52A2):c.505C>T, NP_078807.1(SLC52A2):p.(Arg169Cys) variant in SLC52A2 and NM_033409.3(SLC52A3):c.1316G>A, NP_212134.3(SLC52A3): p.(Gly439Asp) variant in SLC52A3. Both treated children showed improvement on high-dose riboflavin supplementation, highlighting the importance of early recognition of this treatable clinical entity.
Neuromuscular Disorders, 2012
Brown-Vialetto-van Laere (BVVL) and Fazio-Londe (FL) are rare and clinically overlapping motor neurons syndromes. Recently BVVL has been associated with mutations in C20orf54/hRFT2 and defective riboflavin transport. We compared clinical and laboratory features of 6 patients (age range 11-17 years), with features of BVVL and FL overlap syndromes. Patients were assessed as following: blood levels of riboflavin and redox status, electrophysiological, neuroradiological and pulmonary studies, ALS functional rating scale and molecular genetic analysis. Two patients manifested deafness at ages of 3 and 10 years, and developed later subacute progressive ponto-bulbar palsy. A third patient markedly improved after intravenous immunoglobulins (IVIG), but then relapsed remaining unresponsive to treatment; he was not deaf although had abnormal auditory evoked responses (BAERs). The remaining 3 patients had no deafness, although likewise manifested subacute progressive ponto-bulbar palsy. We found hRFT2 mutations in 3/6 patients manifesting deafness or abnormal BAERs. No patient had reduced riboflavin blood levels. However, on riboflavin supplementation (10 mg/kg/day) the most severely affected BVVL patient stopped progression of symptoms following 8 months of treatment. BVVL and FL are severe progressive diseases with overlapping symptoms although only hRFT2 mutated patients manifest deafness. Riboflavin supplementation seems to stabilize and improve progression of the disease.
Journal of Inherited Metabolic Disease, 2012
Brown-Vialetto-Van Laere syndrome (BVVLS [MIM 211530]) is a rare neurological disorder characterized by infancy onset sensorineural deafness and ponto-bulbar palsy. Mutations in SLC52A3 (formerly C20orf54), coding for riboflavin transporter 2 (hRFT2), have been identified as the molecular genetic correlate in several individuals with BVVLS. Exome sequencing of just one single case revealed that compound heterozygosity for two pathogenic mutations in the SLC52A2 gene coding for riboflavin transporter 3 (hRFT3), another member of the riboflavin transporter family, is also associated with BVVLS. Overexpression studies confirmed that the gene products of both mutant alleles have reduced riboflavin transport activities. While mutations in SLC52A3 cause decreased plasma riboflavin levels, concordant with a role of SLC52A3 in riboflavin uptake from food, the SLC52A2-mutant individual had normal plasma riboflavin concentrations, a finding in line with a postulated function of SLC52A2 in riboflavin uptake from blood into target cells.
Treatable childhood neuronopathy caused by mutations in riboflavin transporter RFVT2
Brain : a journal of neurology, 2014
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 init...
Frontiers in pediatrics, 2024
Background: Brown-Vialetto-Van Laere (BVVL) syndrome is an extremely rare autosomal recessive progressive motoneuron disease that is caused by a defect in the riboflavin transporter genes SLC52A2 and SLC52A3. BVVL syndrome has a variable age of presentation, and it is characterized by progressive auditory neuropathy, bulbar palsy, stridor, muscle weakness, and respiratory compromise secondary to diaphragmatic and vocal cord paralysis. BVVL syndrome has a poor prognosis in the absence of treatment, including morbidity with quadriparesis and sensorineural hearing loss, with mortality in the younger age group. Early administration of riboflavin is associated with prolonged survival, low morbidity, and reversal of some clinical manifestations. Case presentation: We describe an 18-month-old male infant with progressive pontobulbar palsy, loss of developmental milestones, and a clinical picture suggestive of chronic inflammatory demyelinating neuropathy. A nerve conduction study revealed axonal neuropathy, while molecular analysis revealed a homozygous mutation in one of the riboflavin transporter genes, SLC52A3, confirming BVVL syndrome. The patient needed long-term respiratory support and a gastrostomy tube to support feeding. With high-dose riboflavin supplementation, he experienced moderate recovery of motor function. Conclusion: This report highlights the importance of considering BVVL syndrome in any patient who presents with the clinical phenotype of pontobulbar palsy and peripheral axonal neuropathy, as early riboflavin treatment may improve or halt disease progression, thus reducing the associated mortality and morbidity.
A juvenile ALS‐like phenotype dramatically improved after high‐dose riboflavin treatment
Annals of Clinical and Translational Neurology, 2020
Riboflavin transporter deficiency (RTD) was recently characterized as a cause of genetic recessive childhood-onset motor neuron disease (MND) with hearing loss, formerly described as Brown-Vialetto-Van-Lear syndrome. We describe a 18-year-old woman with probable RTD mimicking juvenile Amyotrophic Lateral Sclerosis (ALS) who presented with an inaugural respiratory failure and moderate distal four limbs weakness. Only one heterozygous SLC52A3 mutation was detected, but presence of a sub-clinical auditory neuropathy and dramatic improvement under high dose riboflavin argued for a RTD. As RTD probably has a larger phenotypic spectrum than expected, a high dose riboflavin trial should be discussed in young-onset MND.
Clinical, pathological and functional characterization of riboflavin-responsive neuropathy
Brain, 2017
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.