Biotin-thiamine Responsive Basal Ganglia Disease Research Articles

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 theSCL19A3gene.

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

BackgroundBiotin-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.MethodsA retrospective review of the data registry in Kuwait Medical Genetics Center for all cases diagnosed clinically and radiographically and confirmed genetically with BTBGD.ResultsTwenty 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.ConclusionThis 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.

45-Year-Old Woman With Fever and Malaise

45-Year-Old Woman With Fever and Malaise

Early Infantile Thiamine Transporter-2 Deficiency with Epileptic Spasms—A Phenotypic Spectrum with a Novel Mutation

AbstractEpileptic seizures are a frequent feature of thiamine transporter deficiency that may present as a clinical continuum between severe epileptic encephalopathy and mixed focal or generalized seizures. Thiamine metabolism dysfunction syndrome 2 (MIM: 607483) or biotin-thiamine-responsive basal ganglia disease (BTBGD) due to biallelic pathogenic mutation in the SLC19A3 gene is a well-recognized cause of early infantile encephalopathy with a Leigh syndrome-like presentation and a lesser-known phenotype of atypical infantile spasms. We reported a 4-month-old infant who presented with progressive epileptic spasms since 1 month of age, psychomotor retardation, and lactic acidosis. Magnetic resonance imaging (MRI) revealed altered signal intensities in bilateral thalamic and basal ganglia, cerebellum, brainstem, cortical and subcortical white matter. Whole exome sequencing identified a homozygous ENST00000258403.3: c.871G > C (p.Gly291Arg) variant in the SLC19A3 gene. We elucidate the features in the proband, which were an amalgamation of both the above subtypes of the SLC19A3 associated with early infantile encephalopathy. We also highlight the features which were atypical for either “Leigh syndrome-like” or “atypical infantile spasm” phenotypes and suggest that the two separate entities can be merged as a clinical continuum. Treatment outcome with high-dose biotin and thiamine is promising. In addition, we report a novel pathogenic variant in the SLC19A3 gene.

Vitamin responsive conditions in pediatric neurology

Vitamin responsive conditions can be either due to inherited defects in the metabolic pathways resulting in vitamin dependency or due to acquired deficiency states. Due to widespread malnutrition and predominantly vegetarian population in India, vitamin deficiency state is quite common and early identification is essential. Inherited defects, if treated earlier, lead to reduced morbidity and mortality and improvement in long-term neurocognitive outcomes. Various vitamin responsive conditions in pediatric neurology shall be discussed in this review. Infantile presentation of thiamine deficiency results in beriberi, and in adults, it leads to Wernicke’s encephalopathy and Korsakoff psychosis. Biotin thiamine-responsive basal ganglia disease is a defect of thiamine transporter 2, which leads to neuroregression and characteristic neuroimaging features of basal ganglia involvement, it responds to high doses of biotin and thiamine. Riboflavin is an enzyme involved in mitochondrial energy synthesis and is supplemented in various mitochondrial metabolic conditions. Brown-Vialetto-Van Laere syndrome is progressive pontobulbar palsy caused by defect in riboflavin transporters responsive to high doses of riboflavin. Pyridoxine responsive epilepsy presents with pharmacoresistant seizures in neonatal or early infantile age, biotinidase deficiency also presents with similar neurological manifestations, but typical cutaneous symptoms of rash and seborrheic dermatitis also occur. Both are epileptic encephalopathies and any infant presenting with epilepsy not responding to conventional AEDs must be given a trial of pyridoxine, biotin, and folinic acid. Vitamin B12 responsive conditions can include deficiency states, such as those manifesting with peripheral neuropathy and the syndrome of infantile tremor syndrome (developmental delay or regression, tremors, and megaloblastic anemia) as well as inherited disorders of homocysteine and cobalamin metabolism. These disorders are differentiated on the basis of clinical phenotype and laboratory parameters (serum B12, homocysteine levels, methylmalonic acid levels, etc.). Infantile tremor syndrome responds drastically to mega doses of Vitamin B12 and other multivitamins. Vitamin E deficiency causes ataxia with Vitamin E deficiency, other vitamins which can neurological symptoms include Vitamin C (pseudoparalysis) and Vitamin K (central nervous system bleeds). It is imperative for a practicing pediatrician to be well versed with these conditions, as these are potentially treatable conditions.

Biotin–Thiamine Responsive Basal Ganglia Disease Presented as Intractable Seizure in a 1-Month-Old Infant

AbstractBiotin–thiamine responsive basal ganglia disease is a neurometabolic disorder, seen in children presenting with encephalopathy, seizures, and positive family history. The disease is diagnosed based on typical magnetic resonance imaging (MRI) findings and whole exome sequencing but may be initially misdiagnosed as a mitochondrial encephalopathy or an inborn error of metabolism (IEM). We describe the case of an infant who presented with uncontrolled seizures and encephalopathy, responding to high doses of thiamine and biotin. Life-long supplementation of biotin (2–10 mg/kg/day) and thiamine (200–300 mg/day) improves the symptomatology and prevents relapse. Outcomes of the disease are heterogeneous, ranging in scope from complete remission to severe neurological sequelae.

Single gene, two diseases, and multiple clinical presentations: Biotin–thiamine-responsive basal ganglia disease

AimTo present seven new genetically confirmed cases of biotin–thiamin-responsive basal ganglia disease (BTBGD) with different clinical and brain magnetic resonance imaging (MRI) characteristics. Material and methodsGenetic variants, clinical presentations, brain MRI findings, treatment response, and prognosis of seven selected patients with BTBGD, diagnosed with SLC19A3 mutations were described. ResultsAmong seven patients diagnosed with BTBGD, two had early infantile form, four had classic childhood form, and one was asymptomatic. Four different homozygous variants were found in the SLC19A3. Two patients with early infantile form presented with encephalopathy, dystonia, and refractory seizure in the neonatal period and have different variants. Their MRI findings were similar and pathognomonic for the early infantile form. Three siblings had same variants: one presented seizure and encephalopathy at the age of 4 months, one presented seizure at 14 years, and another was asymptomatic at 20 years. Only one of them had normal MRI findings, and the others MRI findings were similar and suggestive of the classic form. Other two siblings; one of them presented with developmental delay, seizure, and dystonia at 18 months and the other presented with subacute encephalopathy and ataxia at 20 months. Their MRI findings were also similar and suggestive of the classic form. ConclusionBTBGD may present with dissimilar clinical characteristics or remain asymptomatic for a long time period even in a family or patients with same variants. Brain MRI patterns may be important for the early diagnosis of BTBGD that would save children’s lives.

Reliability of MRI in detection and differentiation of acute neonatal/pediatric encephalopathy causes among neonatal/pediatric intensive care unit patients

BackgroundCauses of encephalopathy in neonates/pediatrics include hypoxic-ischemic injury (which is the most frequent cause and is defined as any impairment to the brain caused by insufficient blood flow and oxygenation), trauma, metabolic disorders, and congenital and infectious diseases. The aim of this study is to evaluate the value of MRI in detection and possible differentiation of different non-traumatic, non-infectious causes of acute neonatal/pediatric encephalopathy among NICU/PICU patients.ResultsThis retrospective study included 60 selected patients according to the study inclusion and exclusion criteria; all presented with positive MRI findings for non-traumatic, non-infectious acute brain injury. Females (32, 53.3%) were affected more than males (28, 46.7%) with a mean age of 1.1 ± 1.02 years; all presented with variable neurological symptoms and signs that necessitate neonatal intensive care unit/pediatric intensive care unit (NICU/PICU) admission. The final diagnosis of the study group patients were hypoxic ischemia injury (HII) in 39 patients (65%), metachromatic leukodystrophy in 6 patients (10%), biotin-thiamine-responsive basal ganglia disease (BTBGD) and Leigh disease each in 4 patients (6.7%), periventricular leukomalacia (PVL) in 3 patients (5%), and mitochondrial encephalopathy with lactic acidosis and stroke-like episodes syndrome (MELAS) and non-ketotic hyperglycinemia (NKH) each in 2 patients (3.3%).ConclusionMuch attention should be paid to pediatric non-traumatic brain injuries. MRI is a safe modality and should be the first radiological investigation if neurological causes are suggested but should be aided by meticulous clinical evaluation and dedicated laboratory investigations for better characterization and differentiation of various causes of non-traumatic, non-infective brain encephalopathy among NICU/PICU patients. When interpreting MRI, it is essential to have thorough relevant clinical data, gestational age at birth which is prognostic of the pattern of hypoxic-ischemic injury, and the time lag between the onset of HII and the time of performing the MR study.

Genetic heterogeneity in Leigh syndrome: Highlighting treatable and novel genetic causes.

Leigh syndrome (LS), the most common childhood mitochondrial disorder, has characteristic clinical and neuroradiologic features. Mutations in more than 75 genes have been identified in both the mitochondrial and nuclear genome, implicating a high degree of genetic heterogeneity in LS. To profile these genetic signatures and understand the pathophysiology of LS, we recruited 64 patients from 62 families who were clinically diagnosed with LS at Seoul National University Children's Hospital. Mitochondrial genetic analysis followed by whole-exome sequencing was performed on 61 patients. Pathogenic variants in mitochondrial DNA were identified in 18 families and nuclear DNA mutations in 22. The following 17 genes analyzed in 40 families were found to have genetic complexity: MTATP6, MTND1, MTND3, MTND5, MTND6, MTTK, NDUFS1, NDUFV1, NDUFAF6, SURF1, SLC19A3, ECHS1, PNPT1, IARS2, NARS2, VPS13D, and NAXE. Two treatable cases had biotin-thiamine responsive basal ganglia disease, and another three were identified as having defects in the newly recognized genes (VPS13D or NAXE). Variants in the nuclear genes that encoded mitochondrial aminoacyl tRNA synthetases were present in 27.3% of cases. Our findings expand the genetic and clinical spectrum of LS, showing genetic heterogeneity and highlighting treatable cases and those with novel genetic causes.

Biotin–Thiamine Responsive Basal Ganglia Disease: A Treatable Metabolic Encephalopathy—Not to Be Missed!

AbstractBiotin–thiamine responsive basal ganglia disease (BTBGD) is an autosomal recessive neurometabolic disorder, characterized by encephalopathy, extrapyramidal signs following mild infection, trauma or surgery and is potentially reversible with treatment. We describe a 15-month-old female child of Indian-Muslim origin with characteristic clinical and radiological features of BTBGD that showed complete resolution with treatment. A comparison with previously reported cases reveals a different mutation (exon 2 vs. exon 5 in middle east cases) in the SLC19A3 gene that could be specific for the Indian subcontinent. We also emphasize the importance of a trial of vitamins in patients with acute metabolic encephalopathy.

Are diagnostic magnetic resonance patterns life-saving in children with biotin-thiamine-responsive basal ganglia disease?

Biotin-thiamine responsive basal ganglia disease (BTBGD) is an autosomal recessive disorder caused by mutations in the SLC19A3 gene and characterized by recurrent sub-acute episodes of encephalopathy that typically starts in early childhood. This study describes characteristic clinical and magnetic resonance imaging (MRI) findings of six cases of BTBGD diagnosed with newly identified mutations and genetically confirmed, with very early and different presentations compared to cases in the previous literature. Six patients referred from different centers with similar clinical findings were diagnosed with BTBGD with newly identified mutations in the SLC19A3 gene. Two novel mutations in the SLC19A3 gene were identified in two patients at whole exome sequencing analysis. The clinical characteristics, responses to treatment, and electroencephalography (EEG) and MRI findings of these patients were examined. The other four patients presented with similar clinical and cranial MRI findings. These patients were therefore started on high-dose biotin and thiamine therapy, and mutation analysis concerning the SLC19A3 gene was performed. Responses to treatment, clinical courses, EEG findings and follow-up MRI were recorded for all these patients. Age at onset of symptoms ranged from 1 to 3 months. The first symptoms were generally persistent crying and restlessness. Seizures occurred in five of the six patients. Cranial magnetic resonance imaging revealed involvement in the basal ganglia, brain stem, and the parietal and frontal regions in general. The first two patients were siblings, and both exhibited a novel mutation of the SLC19A3 gene. The third and fourth patients were also siblings and also exhibited a similar novel mutation of the SLC19A3 gene. The fifth and sixth patients were not related, and a newly identified mutation was detected in both these subjects. Three novel mutations were thus detected in six patients. BTBGD is a progressive disease that can lead to severe disability and death. Early diagnosis of treatable diseases such as BTBGD is important in order to prevent long-term complications and disability.

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.

Biotin–thiamine–responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment

Background: Biotin–thiamine–responsive basal ganglia disease (BTBGD) is an autosomal recessive neurometabolic disorder caused by mutations in the SLC19A3 gene. The disease is characterized by subacute encephalopathy with confusion, dysphagia, dysarthria, and seizures.Methods: We diagnosed a family affected by BTBGD and studied them including prognosis of cases when diagnosed and treated early in the disease process. We also review the literature comprehensively and summarize all published data about this disorder.Results: Since its first description, a total of 89 cases (46 females and 43 males) have been published in the literature. We studied six patients in this article in which three died before a diagnosis was established, one was diagnosed lately and is currently severely affected, and two were diagnosed early and are currently stable on treatment. The clinical phenotype of each family member was studied in details. In addition, a genetic testing was performed using whole exome sequencing and Sanger sequencing which demonstrated a previously reported homozygous mutation in exon 5 of the SLC19A3 gene c.1264A>G (p.Thr422Ala).Conclusion: BTBGD is a treatable condition if recognized early and managed appropriately. The recognition of this disorder is important to avoid incorrect diagnosis and mismanagement. Children presenting with unexplained encephalopathy and MRI abnormalities including bilateral signal alteration of caudate nucleus and putamen should raise the suspicion for BTBGD and be started immediately on biotin and thiamine regimen since the prognosis of the disease is affected by the timing of treatment initiation. We present a large family affected with this disorder with severe interfamilial variability and different prognosis despite having the same mutation and same environment. A clear genotype–phenotype correlation and the clinical heterogeneity remain to be elucidated. Bad prognostic factors observed in our review include early onset of the disease, missed or delayed diagnosis, systemic involvements including respiratory failure and rhabdomyolysis, and severe neurological deficit or radiological changes at the time of diagnosis and treatment initiation. We observed during our literature review that all patients who presented since birth died despite aggressive treatment. This observation may illustrate that early presentation and disease process leads to a more catastrophic outcome.

Stress‐Induced Upregulation of SLC19A3 is Impaired in Biotin‐Thiamine‐Responsive Basal Ganglia Disease

Biotin-thiamine-responsive basal ganglia disease (BTBGD) is a potentially treatable disorder caused by mutations in the SLC19A3 gene, encoding the human thiamine transporter 2. Manifestation of BTBGD as acute encephalopathy triggered by a febrile infection has been frequently reported, but the underlying mechanisms are not clear. We investigated a family with two brothers being compound heterozygous for the SLC19A3 mutations p.W94R and p.Q393*fs. Post-mortem analysis of the brain of one brother showed a mixture of acute, subacute and chronic changes with cystic and necrotic lesions and hemorrhage in the putamen, and hemorrhagic lesions in the caudate nucleus and cortical layers. SLC19A3 expression was substantially reduced in the cortex, basal ganglia and cerebellum compared with an age-matched control. Importantly, exposure of fibroblasts to stress factors such as acidosis or hypoxia markedly upregulated SLC19A3 in control cells, but failed to elevate SLC19A3 expression in the patient's fibroblasts. These results demonstrate ubiquitously reduced thiamine transporter function in the cerebral gray matter, and neuropathological alterations similar to Wernicke's disease in BTBGD. They also suggest that episodes of encephalopathy are caused by a substantially reduced capacity of mutant neuronal cells to increase SLC19A3 expression, necessary to adapt to stress conditions.

Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease

Biotin-thiamine responsive basal ganglia disease (BTBGD) is a rare metabolic condition caused by mutations in the SLC19A3 gene. BTBGD presents with encephalopathy and significant disease progression when not treated with biotin and/or thiamine. We present a patient of Mexican and European ancestry diagnosed with BTBGD found to have compound heterozygous frameshift mutations, one novel. Our report adds to the genotype-phenotype correlation, highlighting the clinical importance of considering SLC19A3 gene defects as part of the differential diagnosis for Leigh syndrome.