Efficacy of high thiamine dosage in treating patients with biotin thiamine responsive basal ganglia disease: a two case reports.

BACKGROUND: Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare, autosomal recessive neurometabolic disorder caused by mutations in the SLC19A3 gene and characterized by recurrent sub-acute episodes of encephalopathy. Patients with BTBGD have classical neuroimaging findings and a dramatic response to high doses of thiamine. OBJECTIVE: To highlight the advantages of administering a higher dose of thiamine for patients with BTBGD who have not shown improvement with the standard recommended dosage. RESULTS: Herein, we report on two Saudi girls with classical clinical and radiological findings of BTBGD. Hallmark symptoms in these patients included an acute onset of ataxia, tremor, slurred speech, dystonia, and dysphagia. The initial routine laboratory workups were unremarkable. Brain magnetic resonance imaging revealed extensive hyperintense signals in the bilateral basal ganglia, which suggested the diagnosis of a BTBGD. Hence started empirically on biotin 10 mg/kg/day and thiamine 40 mg/kg/day, but there was no noticeable improvement. After increasing the thiamine to 75 mg/kg/day the patients started to improve significantly. Genetic testing was requested and came positive for the mutation of the SLC19A3 gene. After two months of initiating the management, thiamine was reduced to 30 mg/kg/day. Subsequent follow-ups showed complete improvement in their condition with no apparent long-term sequel or relapse. CONCLUSION: we conclude that administration of thiamine at a dosage of up to 40 mg/kg/day may not be sufficient in treating certain patients with BTBGD. Thus, considering a significantly higher dosage could potentially contribute to achieving remission.

Biotin Homeostasis and Human Disorders: Recent Findings and Perspectives.

Biotin (vitamin B7, or vitamin H) is a water-soluble B-vitamin that functions as a cofactor for carboxylases, i.e., enzymes involved in the cellular metabolism of fatty acids and amino acids and in gluconeogenesis; moreover, as reported, biotin may be involved in gene regulation. Biotin is not synthesized by human cells, but it is found in food and is also produced by intestinal bacteria. Biotin status/homeostasis in human individuals depends on several factors, including efficiency/deficiency of the enzymes involved in biotin recycling within the human organism (biotinidase, holocarboxylase synthetase), and/or effectiveness of intestinal uptake, which is mainly accomplished through the sodium-dependent multivitamin transporter. In the last years, administration of biotin at high/"pharmacological" doses has been proposed to treat specific defects/deficiencies and human disorders, exhibiting mainly neurological and/or dermatological symptoms and including biotinidase deficiency, holocarboxylase synthetase deficiency, and biotin-thiamine-responsive basal ganglia disease. On the other hand, according to warnings of the Food and Drug Administration, USA, high biotin levels can affect clinical biotin-(strept)avidin assays and thus lead to false results during quantification of critical biomarkers. In this review article, recent findings/advancements that may offer new insight in the abovementioned research fields concerning biotin will be presented and briefly discussed.

Case report: biotin-thiamine-responsive basal ganglia disease with severe subdural hematoma on magnetic resonance imaging.

Background: Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare, treatable autosomal recessive neurometabolic disorder. This condition eventually leads to severe disability and death if not treated correctly. The clinical features of BTBGD, especially those with unusual complications, are not widely known by neurologists or pediatricians.Case presentation: A 4-month-old male infant was admitted to the hospital with a history of cough for the past 7 days and convulsions of 6 h duration. Physical examination showed confusion, bilateral pupillary light reflex delays, hypertonia of limbs, and brisk tendon reflexes of the limbs. Brain magnetic resonance imaging (MRI) showed multiple abnormal signals in the bilateral basal ganglia, lobes, corpus callosum, brainstem, and brain atrophy. However, his condition continued to worsen. Computed tomography performed 3 months later showed severe subdural hematoma and effusion. Subsequently, he underwent puncture drainage; however, his condition did not improve postoperatively. Repeated MRIs showed increasing subdural hematoma and effusion, and brain atrophy. The patient was diagnosed with BTBGD following whole-genome sequencing, which identified a novel compound heterozygous mutation of SLC19A3 gene. He was treated with biotin and thiamine, and the symptoms gradually improved. Subsequent MRIs showed a decrease in the subdural hematoma and effusion and partial improvement in brain atrophy.Conclusion: To the best of our knowledge, this is the first reported case of BTBGD, complicated by severe subdural hematoma. These observations extend our understanding of the clinical features, neuroimaging spectrum, and gene mutation spectrum of BTBGD. The phenotypic spectrum and pathophysiology of BTBGD are not completely understood and need to be studied further.

Unusual case of biotin-thiamine responsive encephalopathy without basal ganglia involvement.

Biotin-thiamine-responsive encephalopathy, also known as biotin-responsive basal ganglia disease, is characterized by high T2 signal in the basal ganglia (caudate and putamina), which is reported as a typical feature of the disorder. Brain magnetic resonance imaging in our patient, who presented with irritability, poor feeding and prolonged seizures, found multiple areas of restricted diffusion in the cerebral cortex and thalami leading to an initial diagnosis of a mitochondrial disorder. The basal ganglia were not affected. More characteristic chronic findings of T2 prolongation and volume loss were later seen in our patient. The child improved with biotin and thiamine supplementation, a well-known feature of the condition. It is important for the radiologist and treating team to be aware of this variant and pursue further investigations to avoid delay in care and potential fatality.

Biotin-thiamine responsive basal ganglia disease: Identification of a pyruvate peak on brain spectroscopy, novel mutation in SLC19A3, and calculation of prevalence based on allele frequencies from aggregated next-generation sequencing data.

Biotin-thiamine responsive basal ganglia disease is an inborn error of metabolism caused by mutations in SLC19A3, encoding a transporter of thiamine across the plasma membrane. We report a novel mutation identified in the homozygous state in a patient with typical brain MRI changes. In addition, this patient had markedly elevated CSF pyruvate, a low lactate-to-pyruvate molar ratio, and an abnormal pyruvate peak at 2.4 ppm on brain magnetic resonance spectroscopy. Using aggregated exome sequencing data, we calculate the carrier frequency of mutations in SLC19A3 as 1 in 232 individuals in the general population, for an estimated prevalence of the disease of approximately 1 in 215,000 individuals. The disease is thus more frequent than previously recognized, and the presence of a pyruvate peak on spectroscopy could serve as an important diagnostic clue.

Free-thiamine is a potential biomarker of thiamine transporter-2 deficiency: a treatable cause of Leigh syndrome.

Thiamine transporter-2 deficiency is caused by mutations in the SLC19A3 gene. As opposed to other causes of Leigh syndrome, early administration of thiamine and biotin has a dramatic and immediate clinical effect. New biochemical markers are needed to aid in early diagnosis and timely therapeutic intervention. Thiamine derivatives were analysed by high performance liquid chromatography in 106 whole blood and 38 cerebrospinal fluid samples from paediatric controls, 16 cerebrospinal fluid samples from patients with Leigh syndrome, six of whom harboured mutations in the SLC19A3 gene, and 49 patients with other neurological disorders. Free-thiamine was remarkably reduced in the cerebrospinal fluid of five SLC19A3 patients before treatment. In contrast, free-thiamine was slightly decreased in 15.2% of patients with other neurological conditions, and above the reference range in one SLC19A3 patient on thiamine supplementation. We also observed a severe deficiency of free-thiamine and low levels of thiamine diphosphate in fibroblasts from SLC19A3 patients. Surprisingly, pyruvate dehydrogenase activity and mitochondrial substrate oxidation rates were within the control range. Thiamine derivatives normalized after the addition of thiamine to the culture medium. In conclusion, we found a profound deficiency of free-thiamine in the CSF and fibroblasts of patients with thiamine transporter-2 deficiency. Thiamine supplementation led to clinical improvement in patients early treated and restored thiamine values in fibroblasts and cerebrospinal fluid.

Derivation of two iPSC lines (KAIMRCi004-A, KAIMRCi004-B) from a Saudi patient with Biotin-Thiamine-responsive Basal Ganglia Disease (BTBGD) carrying homozygous pathogenic missense variant in the SCL19A3 gene.

The neurometabolic disorder known as biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare autosomal recessive condition linked to bi-allelic pathogenic mutations in the SLC19A3 gene. BTBGD is characterized by progressive encephalopathy, confusion, seizures, dysarthria, dystonia, and severe disabilities. Diagnosis is difficult due to the disease's rare nature and diverse clinical characteristics. The primary treatment for BTBGD at this time is thiamine and biotin supplementation, while its long-term effectiveness is still being investigated. In this study, we have generated two clones of induced pluripotent stem cells (iPSCs) from a 10-year-old female BTBGD patient carrying a homozygous mutation for the pathogenic variant in exon 5 of the SLC19A3 gene, c.1264A > G (p.Thr422Ala). We have confirmed the pluripotency of the generated iPS lines and successfully differentiated them to neural progenitors. Because our understanding of genotype-phenotype correlations in BTBGD is limited, the establishment of BTBGD-iPSC lines with a homozygous SLC19A3 mutation provides a valuable cellular model to explore the molecular mechanisms underlying SLC19A3-associated cellular dysfunction. This model holds potential for advancing the development of novel therapeutic strategies.

Biotin-thiamine responsive basal ganglia disease: a retrospective review of the clinical, radiological and molecular findings of cases in Kuwait with novel variants.

BACKGROUND: Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare autosomal recessive neurometabolic disorder that is caused by biallelic pathogenic SLC19A3 variants and is characterized by subacute encephalopathy associated with confusion, convulsions, dysphagia, dysarthria, or other neurological manifestations. METHODS: A retrospective review of the data registry in Kuwait Medical Genetics Center for all cases diagnosed clinically and radiographically and confirmed genetically with BTBGD. RESULTS: Twenty one cases from 13 different families were diagnosed with BTBGD in Kuwait. Most cases (86%) presented with confusion, dystonia, convulsions, or dysarthria, while three individuals were diagnosed pre-symptomatically during familial targeted genetic screening. Symptoms resolved completely within 2-week of treatment in two-thirds of the symptomatic cases but progressed in six of them to a variety of severe symptoms including severe cogwheel rigidity, dystonia and quadriparesis due to delayed presentation and management. Neuroradiological findings of the symptomatic cases revealed bilateral central changes in the basal ganglia. Two novel homozygous missense SLC19A3 variants were detected in a Kuwaiti and a Jordanian individuals, in addition to the previously reported Saudi founder homozygous variant, c.1264A > G; p.(Thr422Ala) in the remaining cases. Age of diagnosis ranged from newborn to 32 years, with a median age of 2-3 years. All cases are still alive receiving high doses of biotin and thiamine. CONCLUSION: This is the first study reporting the phenotypic and genotypic spectrum of 21 individuals with BTBGD in Kuwait and describing two novel SLC19A3 variants. BTBGD is a treatable neurometabolic disease that requires early recognition and treatment initiation. This study highlights the importance of performing targeted molecular testing of the founder variant in patients presenting with acute encephalopathy in the region.

An unusually mild case of biotin-thiamine-responsive basal ganglia disease.

Background: Biotin-Thiamine-Responsive Basal Ganglia Disease (BTBGD) is a treatable neurometabolic condition associated with pathogenic variants in the SLC19A3 gene. The classical childhood-onset phenotype presents at a mean age of 4 years, ranging from birth to 12 years. These patients present with subacute encephalopathy, dysarthria, dysphagia, dystonia, external ophthalmoplegia, seizures, quadriparesis, and even death. Chronically, an MRI brain reveals atrophy and necrosis of the basal ganglia. Case report: A 16-year-old girl presented in the context of pneumonia with gradual-onset, slowly progressive neurological symptoms. These initial symptoms self-resolved, without treatment with biotin or thiamine, though she had persistent concerns with her writing and memory. MRI brain noted bilateral abnormal signals in the basal ganglia, involving the head and body of the caudate nuclei and the putamen. Whole-exome sequencing (WES) revealed homozygosity for a likely pathogenic variant in the SLC19A3 gene, c.517A > G (p.N173D). Her residual neurological symptoms resolved with biotin and thiamine treatment, with the exception of ongoing memory concerns. Conclusion: We describe a patient presenting with an atypical form of the classical childhood-onset phenotype of BTBGD. Our case emphasizes that BTBGD is a condition that should be considered as a potential diagnosis in all children, including older children, presenting with the new onset of even minor neurological deficits in the context of illness. It highlights the importance of brain MRI and WES in identifying patients with atypical presentations.

Developing of Biotin-Thiamine Responsive Basal Ganglia Disease after Accidental Ingestion of Ethyl Alcohol: A Case Report.

Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare, inherited neurometabolic disorder caused by mutations in the SLC19A3 gene and characterized by recurrent sub-acute episodes of encephalopathy that are often triggered by infections. Patients with BTBGD have classical neuroimaging findings and a dramatic response to high doses of thiamine. Herein, we report a 2 and a half-year-old Saudi girl presented with an acute onset of ataxia, slurred speech, and dysphagia, which was preceded by a history of accidental ingestion of around 20 mL of ethyl alcohol that is used in formulating perfumes 1 day earlier. Her older brother had a similar clinical presentation and was diagnosed with BTBGD. The patient was fully alert and spoke in full sentences with dysarthria. She was unable to walk unassisted. Investigation revealed a positive toxicity test for ethyl alcohol (10 mg/dL), and brain magnetic resonance imaging showed basal ganglia changes consistent with BTBGD. The dramatic response to high doses of thiamine suggested SLC19A3 as a strong candidate gene, and Sanger sequencing revealed a homozygous (NM_025243.4): c.1264A>G (p.Thr422Ala) mutation. Patients with BTBGD should be cautious and aware of ethyl alcohol products, which can lead to a BTBGD crisis. The administration of a high dose of thiamin may be required in patients who have not responded to the recommended dose. Further clinical research is required to determine the optimal doses.

Biotin-thiamine-responsive basal ganglia disease: A case report.

Biotin-Thiamine-Responsive Basal Ganglia Disease is an extremely rare autosomal recessive neurometabolic disorder characterized by recurrent waxing and waning episodes of subacute encephalopathy and seizures. High dose biotin and thiamine administration has been shown to improve symptoms within days, and the symptoms may reappear rapidly if supplementation is discontinued. Here we present a case of a 20-year-old male with classical clinical and imaging findings of Biotin-Thiamine-Responsive Basal Ganglia Disease, with a 12-year delay in diagnosis, finally diagnosed after presenting at our institution based on imaging and subsequent reexamination of exome sequencing. In this report, we review the classic imaging findings in this disease and examine why making the diagnosis can be extremely challenging due to its wide differential. Both clinically and radiographically, this condition demonstrates significant overlap with a vast array of disease entities, ranging from viral or autoimmune encephalitis to metabolic disorders. Finally, we discuss the various negative prognostic predictors described in the literature, several of which were observed in this patient's clinical course.

Beyond the caudate nucleus: Early atypical neuroimaging findings in biotin-thiamine- responsive basal ganglia disease.

BACKGROUND: Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a treatable neurometabolic disease caused by variants in SLC19A3. Typical imaging features include symmetrical involvement of the caudate nuclei and putamina. OBJECTIVE: The study sought to explore classical BTBGD without caudate nucleus involvement, to highlight the importance of recognizing this new pattern early in the disease. METHODS: Individuals with genetically confirmed BTBGD who harbored the same homozygous variant: NM_025243.4 (SLC19A3): c.1264A > G (p.Thr422Ala) and had atypical neuroimaging were recruited. RESULTS: Nine patients with BTBGD had atypical neuroimaging findings on the first MRI scan. The median age at symptom onset was 3 years. All patients presented with classical clinical features of subacute encephalopathy, dystonia, ataxia, and seizures. During the acute crisis, MRI revealed bilateral and symmetric involvement of the putamina in all patients; one showed small caudate nuclei involvement. In addition, the thalami, cerebellum, and brain stem were involved in six patients, seven patients, and three patients, respectively. Treatment included a combination of high doses of thiamine and biotin. One patient died; he did not receive any vitamin supplementation. Two patients who were treated late had severe neurological sequelae, including generalized dystonia and quadriplegia. Six patients treated early had good outcomes with minimal sequelae, including mild dystonia and dysarthria. Two patients showed the classical chronic atrophic and necrotic changes already described. CONCLUSION: The early atypical neuroimaging pattern of BTBGD described here, particularly the lack of caudate nucleus involvement, should not dissuade the clinician and radiologist from considering a diagnosis of BTBGD.

Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia.

Background and Aims: Biotin-thiamine-responsive basal ganglia disease (BTBGD) is an autosomal recessive disorder due to mutations in the SLC19A3-gene, typically seen in early childhood. Materials and Methods: We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration. The magnetic resonance imaging (MRI) of the brain revealed T2-hyperintensities in the basal ganglia, thalamus, cortical, subcortical regions with striatal necrosis suggestive of BTBGD that was confirmed by genetic analysis. She was treated with thiamine and biotin following which there was significant clinical and MRI improvement. Conclusions: BTBGD requires a high index of suspicion in any patient presenting with unexplained rapidly progressive dementia. High doses of biotin and thiamine are the mainstay of the treatment to achieve a favorable outcome.

Biotin-thiamine responsive basal ganglia disease in the era of COVID-19 outbreak diagnosis not to be missed: A case report.

BACKGROUND: Biotin-thiamine-responsive basal ganglia disease (BTRBGD) is a rare treatable autosomal recessive neurometabolic disorder characterized by progressive encephalopathy that eventually leads to severe disability and death if not treated with biotin and thiamine. BTRBGD is caused by mutations in the SLC19A3 gene on chromosome 2q36.6, encoding human thiamine transporter 2 (hTHTR2). Episodes of BTRBGD are often triggered by febrile illness. CASE REPORT: The patient was 2 years 10 months old male child presented with fever and progressive acute encephalopathy associated with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) virus infection. MRI revealed bilateral symmetrical high signal involving both basal ganglia and medial thalami which is swollen with central necrosis, initially diagnosed as acute necrotizing encephalomyelitis with increased severity. Genetic analysis revealed BTRBGD. CONCLUSION: BTRBGD requires high index of suspicion in any patient presenting with acute encephalopathy, characteristic MRI findings (that are difficult to differentiate from necrotizing encephalopathy), regardless of the existence of a proven viral infection.

Report of the Largest Chinese Cohort With SLC19A3 Gene Defect and Literature Review.

Thiamine metabolism dysfunction syndrome 2 (THMD2) is a rare metabolic disorder caused by SLC19A3 mutations, inherited in autosomal recessive pattern. As a treatable disease, early diagnosis and therapy with vitamin supplementation is important to improve the prognosis. So far, the reported cases were mainly from Saudi Arab regions, and presented with relatively simple clinical course because of the hot spot mutation (T422A). Rare Chinese cases were described until now. In this study, we investigated 18 Chinese THMD2 patients with variable phenotypes, and identified 23 novel SLC19A3 mutations, which expanded the genetic and clinical spectrum of the disorder. Meanwhile, we reviewed all 146 reported patients from different countries. Approximately 2/3 of patients presented with classical BTBGD, while 1/3 of patients manifested as much earlier onset and poor prognosis, including infantile Leigh-like syndrome, infantile spasms, neonatal lactic acidosis and infantile BTBGD. Literature review showed that elevated lactate in blood and CSF, as well as abnormal OXPHOS activities of muscle or skin usually correlated with infantile phenotypes, which indicated poor outcome. Brainstem involvement on MRI was more common in deceased cases. Thiamine supplementation is indispensable in the treatment of THMD2, whereas combination of biotin and thiamine is not superior to thiamine alone. But biotin supplementation does work in some patients. Genotypic-phenotypic correlation remains unclear which needs further investigation, and biallelic truncated mutations usually led to more severe phenotype.

Vitamin-Responsive Movement Disorders in Children.

Movement disorders in childhood comprise a heterogeneous group of conditions that lead to impairment of voluntary movement, abnormal postures, or inserted involuntary movements. Movement disorders in children are frequently caused by metabolic disorders, both inherited and acquired. Many of these respond to vitamin supplementation. Examples include infantile tremor syndrome, biotinidase deficiency, biotin-thiamine-responsive basal ganglia disease, pyruvate dehydrogenase deficiency, aromatic amino acid decarboxylase deficiency, ataxia with vitamin E deficiency, abetalipoproteinemia, cerebral folate deficiency, and cobalamin metabolism defects. Recognition of these disorders by pediatricians and neurologists is imperative as they are easily treated by vitamin supplementation. In this review, we discuss vitamin-responsive movement disorders in children.

Neonatal form of biotin-thiamine-responsive basal ganglia disease. Clues to diagnosis.

Degerliyurt A, Gündüz M, Ceylaner S, Ünal Ö, Ünal S. Neonatal form of biotin-thiamine-responsive basal ganglia disease. Clues to diagnosis. Turk J Pediatr 2019; 61: 261-266. Biotin-thiamine-responsive basal ganglia disease is characterized by seizures, dystonia and encephalopathy attacks, with an acute-subacute onset in childhood. It causes cerebral damage especially with caudate head and putamen involvement and may lead to severe sequelae and even death if left untreated. We report a patient with the neonatal form of biotin-thiamine-responsive basal ganglia disease who presented with encephalopathy and lactic acidosis in the neonatal period together with the diagnostic magnetic resonance imaging (MRI) clues. MRI in the neonatal period revealed bilateral involvement of the putamen, thalamus, and perirolandic cortical regions. However, MRI obtained at 32 months revealed involvement of the caudate nuclei in addition to the putamen and thalami. The neuroimaging findings of our patient and relevant literature indicate that patients with biotin-thiamine-responsive basal ganglia disease who are symptomatic in the neonatal period have putamen, thalami, and perirolandic cortical involvement. However, these patients do not have caudate involvement, unlike the patients who present in childhood.

Biotin-Thiamine Responsive Encephalopathy: Report of an Egyptian Family with a Novel SLC19A3 Mutation and Review of the Literature.

Biotin-thiamine responsive basal ganglia disease (BTRBGD) is an autosomal recessive neurometabolic disorder with poor genotype-phenotype correlation, caused by mutations in the SLC19A3 gene on chromosome 2q36.6. The disease is characterized by three stages: stage 1 is a sub-acute encephalopathy often triggered by febrile illness; stage 2 is an acute encephalopathy with seizures, loss of motor function, developmental regression, dystonia, external ophthalmoplegia, dysphagia, and dysarthria; stage 3 is represented by chronic or slowly progressive encephalopathy. Clinical and biochemical findings, as well as the magnetic resonance imaging (MRI) pattern, resemble those of Leigh's syndrome, so that BTRBGD can be misdiagnosed as a mitochondrial encephalopathy.Here we report the clinical and radiological phenotypes of two siblings diagnosed with BTRBGD in which a novel SLC19A3 mutation (NM_025243.3: c.548C > T; p.Ala183Val) was found by whole exome sequencing (WES) of the family members.

Biotin-Thiamine-Responsive Basal Ganglia Disease: Case Report and Follow-Up of a Patient With Poor Compliance.

BACKGROUND: Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a rare treatable autosomal recessive neurometabolic disorder characterized by progressive encephalopathy that eventually leads to severe disability and death if not treated with biotin and thiamine supplements. OBJECTIVES: We aimed to determine the optimal management of BTBGD presenting in acute encephalopathic episodes. METHOD: Case report. RESULTS: An 8-year-old girl born to consanguineous parents was diagnosed with BTBGD at the age of 3 years after presenting with acute encephalopathy and ataxia. The patient was treated with biotin and thiamine, and the family was instructed to continue these medications for life. When she was 7 years old, her supplements were stopped for 2 weeks for social reasons. Afterward, the patient began to have tremor in both hands and an unsteady gait. The family then resumed the medications at the usual dosages. However, the patient remained symptomatic. The patient was admitted with acute BTBGD because of discontinuation of medications. The patient's condition was then managed with high doses of intravenous thiamine and oral biotin. She showed gradual improvement after 48 hours. She was then discharged home 1 week later with residual mild upper and lower limb tremor, as well as right lower limb dystonia. Further follow-up showed a good neurological condition with no apparent long-term sequel. The family was further educated about the importance of strict compliance. CONCLUSION: Patients with BTBGD should remain on lifelong treatment with thiamine and biotin. For those who present with acute relapse, we recommend inpatient treatment with high doses of intravenous thiamine and oral biotin. Further clinical research is required to determine the optimal doses and durations.