Biotin-Thiamine-Responsive Basal Ganglia Disease

Mendelian MONDO:0011841 Pathograph 24 Show in embeddings browser Basal Ganglia Disorder Hereditary Neurological Disease Neurometabolic Disorder

Biotin-thiamine-responsive basal ganglia disease is a rare autosomal recessive neurometabolic disorder caused by biallelic SLC19A3 variants that impair thiamine transporter 2 function. It typically presents with subacute encephalopathy, seizures, dysarthria or dysphagia, and movement disorder, often after febrile illness, with characteristic bilateral basal ganglia MRI abnormalities that may extend to thalamic, cortical, and subcortical regions. Early high-dose thiamine and biotin can reverse symptoms and prevent progression, whereas delayed diagnosis is associated with severe neurologic disability or death.

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1
Mappings
1
Definitions
1
Inheritance
3
Pathophys.
2
Histopath.
15
Phenotypes
2
Gaps
24
Pathograph
1
Genes
1
Variants
4
Medical Actions
3
Subtypes
1
Differentials
2
Models
13
References
1
Deep Research
🏷

Classifications

Harrison's Part
NEUROLOGIC
🔗

Mappings

MONDO
MONDO:0011841 biotin-responsive basal ganglia disease
skos:exactMatch Orphanet ORPHA:65284
ORPHA:65284 maps exactly to MONDO:0011841 and defines the current biotin-thiamine-responsive basal ganglia disease scope.
📘

Definitions

1
👪

Inheritance

1
Autosomal recessive inheritance HP:0000007
BTBGD is caused by biallelic pathogenic variants in SLC19A3. When both parents are heterozygous, each sibling has a 25% chance of being affected at conception.
Autosomal recessive inheritance
Show evidence (3 references)
ORPHA:65284 SUPPORT Other
"Autosomal recessive"
Orphanet records autosomal recessive inheritance.
PMID:36657988 SUPPORT Human Clinical
"Biotin thiamine responsive basal ganglia disease (BTRBGD) is an inherited autosomal recessive disorder that results from the inability of thiamine to cross the blood-brain barrier."
Clinical case report and review states the autosomal recessive inheritance and thiamine-transport basis.
PMID:24260777 SUPPORT Human Clinical
"If both parents are known to be heterozygous for an SLC19A3 pathogenic variant, each sib of an affected individual has at conception a 25% chance of being affected, a 50% chance of being an asymptomatic carrier, and a 25% chance of being unaffected and not a carrier."
GeneReviews provides the explicit autosomal-recessive recurrence risks requested in review.
◆

Subtypes

3
Early-infantile biotin-thiamine-responsive basal ganglia disease
Presentation before age three months, with vomiting, feeding difficulty, encephalopathy, hypotonia, seizures, and respiratory failure. This form has a poorer prognosis than classic childhood and adult presentations, including despite vitamin treatment in some infants.
Show evidence (2 references)
PMID:24260777 SUPPORT Human Clinical
"Early-infantile BTBGD presents before age three months with vomiting, feeding difficulties, encephalopathy, hypotonia, seizures, and respiratory failure."
The current GeneReviews summary defines the early-infantile presentation and its core manifestations.
PMID:24260777 SUPPORT Human Clinical
"Prompt administration of biotin and thiamine early in the disease course results in partial or complete improvement within days in classic and adult BTBGD; however, most infants with early-infantile BTBGD have a poor outcome."
GeneReviews directly supports the poorer prognosis of the early-infantile presentation despite the treatability of later presentations.
Classic childhood biotin-thiamine-responsive basal ganglia disease
Usually presents between ages three and ten years with recurrent subacute encephalopathy, confusion, seizures, ataxia, cranial motor abnormalities, dysphagia, dystonia, and rigidity. Febrile illness, mild trauma, or other stress commonly precedes an episode.
Show evidence (2 references)
PMID:24260777 SUPPORT Human Clinical
"Classic BTBGD presents between ages three and ten years with recurrent subacute encephalopathy manifesting as confusion, seizures, ataxia, supranuclear facial palsy, external ophthalmoplegia, and/or dysphagia that, if left untreated, can eventually lead to coma and even death."
The current GeneReviews summary defines the age range and clinical spectrum of classic BTBGD.
PMID:24260777 SUPPORT Human Clinical
"Dystonia and cogwheel rigidity are nearly always present; hyperreflexia, ankle clonus, and Babinski responses are common. Hemiparesis or quadriparesis may be seen. Episodes are often triggered by febrile illness or mild trauma or stress."
GeneReviews supports the movement-disorder manifestations and common physiologic-stress triggers included in the classic presentation.
Adult Wernicke-like biotin-thiamine-responsive basal ganglia disease
A rare presentation after age ten years with acute status epilepticus, ataxia, nystagmus, diplopia, or ophthalmoplegia. The published clinical base is much smaller than for childhood BTBGD.
Show evidence (1 reference)
PMID:24260777 SUPPORT Human Clinical
"Adult Wernicke-like encephalopathy BTBGD, described in three individuals to date, presents after age ten years with acute onset of status epilepticus, ataxia, nystagmus, diplopia, and ophthalmoplegia."
GeneReviews defines the adult presentation and explicitly conveys its limited case base.
?

Discussions and Knowledge Gaps

2
Does biotin independently improve BTBGD outcomes when added to high-dose thiamine, and if so through what mechanism?
KNOWLEDGE GAP OPEN gap_biotin_independent_contribution
Attached to
treatments#High-dose thiamine and biotin supplementation pathophysiology#SLC19A3 thiamine transporter deficiency
Clinical reports generally administer both vitamins without randomized component or dose comparisons. Structural and cellular uptake work does not detect biotin interaction with SLC19A3, so the historical combination regimen should not be interpreted as proof that both components act through the transporter.
Show evidence (1 reference)
PMID:39358356 SUPPORT In Vitro
"biotin does not interact with the transporter"
This establishes the lack of observed SLC19A3 binding or uptake effect, but does not exclude an independent clinical benefit through another mechanism.
Why does a broadly expressed thiamine-transporter defect preferentially injure basal ganglia and other cerebral gray matter during physiologic stress?
KNOWLEDGE GAP OPEN gap_selective_brain_vulnerability
Attached to
pathophysiology#SLC19A3 thiamine transporter deficiency pathophysiology#Stress-triggered cerebral thiamine-transport failure pathophysiology#Basal ganglia and gray-matter injury animal_models#Mus musculus
Patient-cell studies support impaired stress-induced transporter upregulation, and the knockout model shows reduced brain thiamine and metabolic changes. Neither establishes why particular gray-matter regions are selectively vulnerable or which stress-dependent metabolic bottleneck causes the lesion pattern.
Show evidence (2 references)
PMID:24372704 SUPPORT In Vitro
"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."
Patient fibroblasts demonstrate impaired stress adaptation but do not resolve regional brain vulnerability.
PMID:37623829 SUPPORT Model Organism
"mutation or inhibition of THTR2 may alter the brain metabolome and reduce the thiamine reservoir for TDP biosynthesis."
The mouse study provides a metabolic hypothesis while leaving the region-selective human injury mechanism unresolved.
⚙

Pathophysiology

3
SLC19A3 thiamine transporter deficiency
Pathogenic SLC19A3 variants reduce thiamine transporter 2 function, limiting thiamine transport into and within the central nervous system.
SLC19A3 hgnc:16266 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves SLC19A3 (hgnc:16266). hgnc:16266 is a gene from the HUGO Gene Nomenclature Committee.
thiamine transport GO:0015888 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased thiamine transport (GO:0015888). GO:0015888 is a biological process from the Gene Ontology. ↓ DECREASED
thiamine transmembrane transporter activity GO:0015234 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased thiamine transmembrane transporter activity (GO:0015234). GO:0015234 is a molecular function from the Gene Ontology. ↓ DECREASED
blood brain barrier UBERON:0000120 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in blood brain barrier (UBERON:0000120). UBERON:0000120 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Stress-triggered cerebral thiamine-transport failure Mutant SLC19A3 limits the adaptive thiamine-transport response needed during physiologic stress.
Show evidence (3 references)
PMID:24372704 SUPPORT In Vitro
"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."
Cell/tissue study states the causal gene and thiamine transporter 2 function.
PMID:36657988 SUPPORT Human Clinical
"Biotin thiamine responsive basal ganglia disease (BTRBGD) is an inherited autosomal recessive disorder that results from the inability of thiamine to cross the blood-brain barrier."
Clinical review links disease mechanism to impaired thiamine entry across the blood-brain barrier.
PMID:39358356 SUPPORT In Vitro
"Here, we report seven cryo-electron microscopy (cryo-EM) structures of the human thiamine transporter SLC19A3 in complex with various ligands. Conformation-specific nanobodies enable us to capture different states of SLC19A3's transport cycle, revealing the molecular details of thiamine..."
Structural and functional work directly establishes the molecular substrate-recognition and transport cycle represented by this node.
Stress-triggered cerebral thiamine-transport failure
Febrile illness, acidosis, hypoxia, and other stressors fail to induce adequate SLC19A3 upregulation in patient cells, reducing adaptive thiamine availability when neuronal demand is high.
cellular response to hypoxia GO:0071456 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal cellular response to hypoxia (GO:0071456). GO:0071456 is a biological process from the Gene Ontology. ⚠ ABNORMAL thiamine transport GO:0015888 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased thiamine transport (GO:0015888). GO:0015888 is a biological process from the Gene Ontology. ↓ DECREASED
brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in brain (UBERON:0000955). UBERON:0000955 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Basal ganglia and gray-matter injury Cerebral thiamine-transport failure produces Wernicke-like injury with basal ganglia vulnerability.
Lactic acidosis Severe infantile presentations may include elevated lactate/lactic acidosis during metabolic decompensation.
Show evidence (2 references)
PMID:24372704 SUPPORT In Vitro
"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."
Patient fibroblast data show failure of stress-induced SLC19A3 upregulation.
PMID:24372704 SUPPORT In Vitro
"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."
Authors connect impaired stress adaptation to encephalopathic episodes.
Basal ganglia and gray-matter injury
Impaired cerebral thiamine transport injures basal ganglia and other gray matter regions, producing bilateral basal ganglia lesions, Wernicke-like pathology, seizures, encephalopathy, and movement disorder.
neuron CL:0000540 Cell Ontology (CL) Relation: this pathophysiological event involves this cell type This pathophysiological event involves neuron (CL:0000540). CL:0000540 is a cell type from the Cell Ontology.
basal ganglion UBERON:0002420 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in basal ganglion (UBERON:0002420). UBERON:0002420 is an anatomical location from the Uberon multi-species anatomy ontology. brain UBERON:0000955 Uberon multi-species anatomy ontology (UBERON) Relation: this pathophysiological event occurs in this anatomical location This pathophysiological event occurs in brain (UBERON:0000955). UBERON:0000955 is an anatomical location from the Uberon multi-species anatomy ontology.
Downstream
Subacute encephalopathy Cerebral gray-matter injury manifests clinically as acute or subacute encephalopathy.
Confusion The encephalopathic gray-matter injury state includes confusion or altered mental status.
Cognitive impairment Adult Wernicke-like BTBGD gray-matter injury can present with rapidly progressive cognitive impairment.
Hypersomnolence The acute encephalopathic CNS injury state can include hypersomnolence during BTBGD episodes.
Seizures Injured cerebral networks during BTBGD episodes are associated with seizures.
Movement disorder and dystonia Basal ganglia injury produces extrapyramidal movement disorder and dystonia.
Cogwheel rigidity Basal ganglia dysfunction in classic BTBGD produces extrapyramidal cogwheel rigidity.
Hyperreflexia BTBGD can include corticospinal or upper-motor-neuron signs such as hyperreflexia during classic presentations.
Ankle clonus Corticospinal involvement in classic BTBGD can manifest as ankle clonus.
Babinski sign Corticospinal involvement in classic BTBGD can manifest as Babinski responses.
Dysphagia BTBGD encephalopathic CNS injury can include bulbar dysfunction with dysphagia.
Dysarthria BTBGD encephalopathic CNS injury can include dysarthria.
Ataxia Wernicke-like gray-matter involvement can present with ataxia in adult BTBGD.
Bilateral basal ganglia MRI abnormalities Basal ganglia lesions are visible as characteristic bilateral MRI signal abnormalities.
Show evidence (2 references)
PMID:24372704 SUPPORT Human Clinical
"These results demonstrate ubiquitously reduced thiamine transporter function in the cerebral gray matter, and neuropathological alterations similar to Wernicke's disease in BTBGD."
Human brain tissue findings support reduced transporter function and Wernicke-like gray-matter pathology.
PMID:28677371 SUPPORT Human Clinical
"The central nervous system lesions found in the patients displayed almost clearly a specific pattern for SLC19A3 defect, as previously proposed in diagnostic criteria."
Neuropathology/MRI study supports a specific SLC19A3-related CNS lesion pattern.
✶

Histopathology

2
Necrotic and hemorrhagic basal ganglia lesions
Post-mortem BTBGD brain tissue can show mixed acute, subacute, and chronic neuropathologic injury with cystic/necrotic putamen lesions, hemorrhagic caudate lesions, cortical-layer hemorrhage, and Wernicke-like gray-matter alterations.
Show evidence (2 references)
PMID:24372704 SUPPORT Human Clinical
"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."
Post-mortem human brain analysis documents necrotic and hemorrhagic basal ganglia/cortical lesions.
PMID:24372704 SUPPORT Human Clinical
"neuropathological alterations similar to Wernicke's disease in BTBGD."
The same study links BTBGD pathology to Wernicke-like gray-matter injury.
SLC19A3-specific central nervous system lesion pattern
Neuropathology and MRI studies support a recognizable central nervous system lesion pattern in patients with SLC19A3 variants.
Show evidence (1 reference)
PMID:28677371 SUPPORT Human Clinical
"The central nervous system lesions found in the patients displayed almost clearly a specific pattern for SLC19A3 defect, as previously proposed in diagnostic criteria."
Dedicated neuropathology/MRI study supports a specific SLC19A3-related CNS lesion pattern.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Biotin-Thiamine-Responsive Basal Ganglia Disease Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

15
Digestive 1
Dysphagia HP:0002015 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysphagia (HP:0002015). HP:0002015 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:27905264 SUPPORT Human Clinical
"The disease is characterized by subacute encephalopathy with confusion, dysphagia, dysarthria, and seizures."
Clinical review lists dysphagia among characteristic findings.
Metabolism 1
Lactic acidosis HP:0003128 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Lactic acidosis (HP:0003128). HP:0003128 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
PMID:27896110 SUPPORT Human Clinical
"Four different phenotypes have been described; infantile lactic acidosis with encephalopathy"
Full-text review identifies infantile lactic acidosis with encephalopathy as one recognized BTBGD presentation.
PMID:27896110 SUPPORT Human Clinical
"Biochemical analysis revealed elevated blood lactate at 3.8 mmol/L (nl 0.6-2.2)"
Patient biochemical testing documents elevated blood lactate.
Nervous System 10
Subacute encephalopathy HP:0001298 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Encephalopathy (HP:0001298), qualified as temporality subacute. HP:0001298 is a phenotype from the Human Phenotype Ontology.
Temporal: SUBACUTE
Show evidence (2 references)
ORPHA:65284 SUPPORT Other
"A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness."
Orphanet definition directly identifies subacute encephalopathy.
PMID:27905264 SUPPORT Human Clinical
"The disease is characterized by subacute encephalopathy with confusion, dysphagia, dysarthria, and seizures."
Clinical review identifies subacute encephalopathy with associated neurologic features.
Confusion HP:0001289 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Confusion (HP:0001289). HP:0001289 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:65284 SUPPORT Other
"A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness."
Orphanet lists confusion within the defining presentation.
Seizures HP:0001250 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:65284 SUPPORT Other
"A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness."
Orphanet lists seizures in the defining presentation.
PMID:35532649 SUPPORT Human Clinical
"We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration."
Adult BTBGD case confirms seizures in a genetically confirmed patient.
Movement disorder and dystonia HP:0001332 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dystonia (HP:0001332). HP:0001332 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:65284 SUPPORT Other
"A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness."
Orphanet lists movement disorder in the defining presentation; dystonia is a specific movement-disorder manifestation supported by the clinical case.
PMID:35532649 SUPPORT Human Clinical
"We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration."
Genetically confirmed adult BTBGD case documents generalized dystonia.
Hyperreflexia HP:0001347 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hyperreflexia (HP:0001347). HP:0001347 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24260777 SUPPORT Human Clinical
"hyperreflexia, ankle clonus, and Babinski responses are common."
GeneReviews lists hyperreflexia among common classic BTBGD neurologic signs.
Dysarthria HP:0001260 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dysarthria (HP:0001260). HP:0001260 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:27905264 SUPPORT Human Clinical
"The disease is characterized by subacute encephalopathy with confusion, dysphagia, dysarthria, and seizures."
Clinical review lists dysarthria among characteristic findings.
Ataxia HP:0001251 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ataxia (HP:0001251). HP:0001251 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:35532649 SUPPORT Human Clinical
"We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration."
Genetically confirmed adult BTBGD case documents ataxia.
Bilateral basal ganglia MRI abnormalities Abnormal basal ganglia morphology HP:0002134 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal basal ganglia morphology (HP:0002134). HP:0002134 is a phenotype from the Human Phenotype Ontology.
Show evidence (4 references)
ORPHA:65284 SUPPORT Other
"Imaging may reveal bilateral lesions in the basal ganglia."
Orphanet describes the bilateral basal ganglia imaging pattern.
PMID:27905264 SUPPORT Human Clinical
"Children presenting with unexplained encephalopathy and MRI abnormalities including bilateral signal alteration of caudate nucleus and putamen should raise the suspicion for BTBGD"
Review highlights bilateral caudate and putamen signal alteration as a diagnostic clue.
PMID:35532649 SUPPORT Human Clinical
"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"
Adult case report documents thalamic, cortical, and subcortical involvement in addition to basal ganglia abnormalities.
+ 1 more reference
Cognitive impairment HP:0100543 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cognitive impairment (HP:0100543). HP:0100543 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:35532649 SUPPORT Human Clinical
"We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration."
Genetically confirmed adult BTBGD case documents rapidly progressive cognitive impairment.
Hypersomnolence Drowsiness HP:0002329 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hypersomnolence, annotated with Drowsiness (HP:0002329). HP:0002329 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:35532649 SUPPORT Human Clinical
"We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration."
Genetically confirmed adult BTBGD case documents hypersomnolence during the acute episode.
Other 3
Cogwheel rigidity HP:0002396 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Cogwheel rigidity (HP:0002396). HP:0002396 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24260777 SUPPORT Human Clinical
"Dystonia and cogwheel rigidity are nearly always present"
GeneReviews states that cogwheel rigidity is nearly always present in classic BTBGD.
Ankle clonus HP:0011448 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ankle clonus (HP:0011448). HP:0011448 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24260777 SUPPORT Human Clinical
"hyperreflexia, ankle clonus, and Babinski responses are common."
GeneReviews lists ankle clonus among common classic BTBGD neurologic signs.
Babinski sign HP:0003487 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Babinski sign (HP:0003487). HP:0003487 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24260777 SUPPORT Human Clinical
"hyperreflexia, ankle clonus, and Babinski responses are common."
GeneReviews lists Babinski responses among common classic BTBGD neurologic signs.
🧬

Genetic Associations

1
Biallelic SLC19A3 pathogenic variants (Biallelic SLC19A3 pathogenic variants cause BTBGD.)
Gene: SLC19A3 hgnc:16266 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is SLC19A3 (hgnc:16266). hgnc:16266 is a gene from the HUGO Gene Nomenclature Committee. relationship_type: CAUSATIVE variant_origin: GERMLINE
Show evidence (2 references)
ORPHA:65284 SUPPORT Other
"SLC19A3 | solute carrier family 19 member 3 | hgnc:16266 | Disease-causing germline mutation(s) in"
Orphanet records SLC19A3 as disease-causing.
PMID:27896110 SUPPORT Human Clinical
"Whole exome sequencing (WES) was performed at Baylor College of Medicine, Medical Genetics Laboratory and confirmed compound heterozygous frameshift mutations in the SLC19A3 gene in trans"
Patient sequencing identified biallelic SLC19A3 frameshift variants in trans.
Variants (1)
SLC19A3 c.1264A>G (p.Thr422Ala)
Homozygous p.Thr422Ala is a Saudi founder variant and accounted for most cases in a 21-person Kuwait cohort. Structural work places Thr422 in the outer transporter region and supports impaired thiamine affinity and transport, but this regional enrichment should not be generalized to all ancestries.
Show evidence (2 references)
PMID:37670342 SUPPORT Human Clinical
"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."
The regional cohort identifies the founder allele and distinguishes it from two newly observed homozygous missense variants.
PMID:39358356 SUPPORT In Vitro
"Structural changes in this region might explain the loss of affinity and transport activity of the Thr422Ala mutant."
Cryo-EM-guided interpretation supports a structural basis for impaired transport but does not by itself establish clinical severity.
🗃️

External Assertions

2
Orphanet biotin-thiamine-responsive basal ganglia disease record
Orphanet structured disease record ORPHA:65284
Orphanet's ORPHA:65284 structured record supplies the disease definition, synonyms, inheritance, onset, prevalence, disease-gene assertion, and exact MONDO mapping used in this entry.
Show evidence (2 references)
ORPHA:65284 SUPPORT Other
"MONDO:0011841 | Exact"
Orphanet maps ORPHA:65284 exactly to the MONDO concept used here.
ORPHA:65284 SUPPORT Other
"SLC19A3 | solute carrier family 19 member 3 | hgnc:16266 | Disease-causing germline mutation(s) in"
Orphanet records SLC19A3 as the disease-causing gene for ORPHA:65284.
Orphanet thiamine-responsive encephalopathy record
Orphanet structured disease record ORPHA:199348
ORPHA:199348 is a thiamine-responsive encephalopathy record with SLC19A3 and OMIM:607483 cross-references that overlaps the BTBGD disease concept.
Show evidence (2 references)
ORPHA:199348 SUPPORT Other
"Thiamine-responsive encephalopathy is a Wernicke-like encephalopathy characterized by seizures responsive to high doses of thiamine."
The older Orphanet record supports the thiamine-responsive encephalopathy phenotype.
ORPHA:199348 SUPPORT Other
"SLC19A3 | solute carrier family 19 member 3 | hgnc:16266 | Disease-causing germline mutation(s) in"
ORPHA:199348 also records SLC19A3 as the disease-causing gene.
💊

Medical Actions

4
High-dose thiamine and biotin supplementation
Category: Therapeutic Action: vitamin supplementationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is vitamin supplementation, annotated with Nutritional Supplementation (NCIT:C15425). NCIT:C15425 is a clinical intervention from the NCI Thesaurus. Ontology label: Nutritional Supplementation NCIT:C15425
Agent: thiamine CHEBI:18385 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses thiamine, annotated with thiamine(1+) (CHEBI:18385). CHEBI:18385 is a therapeutic agent from Chemical Entities of Biological Interest. biotin CHEBI:15956 Chemical Entities of Biological Interest (CHEBI) Relation: this treatment uses this therapeutic agent This treatment uses biotin (CHEBI:15956). CHEBI:15956 is a therapeutic agent from Chemical Entities of Biological Interest.
High-dose oral thiamine and biotin should begin as early as possible when BTBGD is suspected and continue lifelong. During acute decompensation, thiamine may be doubled and given intravenously. Clinical support comes from observational cohorts and case series; the independent contribution of biotin to the combination remains mechanistically unresolved.
Mechanism Target:
BYPASSES SLC19A3 thiamine transporter deficiency — High-dose thiamine increases substrate availability despite reduced SLC19A3 transporter function.
Show evidence (1 reference)
PMID:27896110 SUPPORT Human Clinical
"This treatment strategy is supported by in vitro studies suggesting that high doses of thiamine and biotin restore insufficient thiamine transport by overexpression of SLC19A3 gene"
Human clinical case report/review cites in vitro support that high-dose vitamins restore insufficient SLC19A3-mediated thiamine transport.
MODULATES Stress-triggered cerebral thiamine-transport failure — Early vitamin supplementation supports thiamine availability during stress-triggered episodes.
Show evidence (1 reference)
PMID:27905264 SUPPORT Human Clinical
"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..."
Clinical review supports immediate vitamin treatment during suspected encephalopathic episodes.
Target Phenotypes: Encephalopathy HP:0001298 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Encephalopathy (HP:0001298), qualified as temporality subacute. HP:0001298 is a phenotype from the Human Phenotype Ontology. Confusion HP:0001289 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Confusion (HP:0001289). HP:0001289 is a phenotype from the Human Phenotype Ontology. Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology. Dysphagia HP:0002015 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Dysphagia (HP:0002015). HP:0002015 is a phenotype from the Human Phenotype Ontology. Dysarthria HP:0001260 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Dysarthria (HP:0001260). HP:0001260 is a phenotype from the Human Phenotype Ontology. Dystonia HP:0001332 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Dystonia (HP:0001332). HP:0001332 is a phenotype from the Human Phenotype Ontology. Ataxia HP:0001251 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Ataxia (HP:0001251). HP:0001251 is a phenotype from the Human Phenotype Ontology. Abnormal basal ganglia morphology HP:0002134 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Abnormal basal ganglia morphology (HP:0002134). HP:0002134 is a phenotype from the Human Phenotype Ontology.
🔬 3D Structures:
8S5U cryo-EM ⚗️ thiamine
Human SLC19A3 in an outward-open, thiamine-bound cryo-EM state, providing direct structural context for thiamine recognition by the therapeutic target.
Show evidence (5 references)
PMID:24260777 SUPPORT Human Clinical
"Biotin (5-10 mg/kg/day) and thiamine (up to 40 mg/kg/day with a maximum of 1,500 mg daily) are given orally as early in the disease course as possible and are continued lifelong."
Current GeneReviews guidance supports early initiation and lifelong oral thiamine and biotin treatment.
ORPHA:65284 SUPPORT Other
"The disease usually becomes symptomatic in childhood and is life-threatening if left untreated, but symptoms can be reversed and progression prevented by treatment with high doses of biotin and thiamine."
Orphanet directly supports high-dose biotin and thiamine as disease-modifying treatment.
PMID:35532649 SUPPORT Human Clinical
"High doses of biotin and thiamine are the mainstay of the treatment to achieve a favorable outcome."
Adult case report and review supports high-dose vitamin treatment.
+ 2 more references
Acute encephalopathy supportive care
Category: Therapeutic Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Acute decompensation may require intensive-care management of seizures and raised intracranial pressure, alongside escalation of disease-specific thiamine treatment.
Target Phenotypes: Encephalopathy HP:0001298 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Encephalopathy (HP:0001298), qualified as temporality subacute. HP:0001298 is a phenotype from the Human Phenotype Ontology. Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24260777 SUPPORT Human Clinical
"Acute encephalopathic episodes may require care in an ICU to manage seizures and increased intracranial pressure; thiamine may be increased to double the regular dose and given intravenously."
Current GeneReviews guidance describes supportive critical care and acute thiamine escalation during encephalopathic episodes.
Avoidance of sodium valproate and ACTH
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Sodium valproate should be avoided for epilepsy treatment in BTBGD, and ACTH used for epileptic spasms can induce status dystonicus.
Target Phenotypes: Seizure HP:0001250 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Seizure (HP:0001250). HP:0001250 is a phenotype from the Human Phenotype Ontology. Dystonia HP:0001332 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Dystonia (HP:0001332). HP:0001332 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:24260777 SUPPORT Human Clinical
"Avoid use of sodium valproate to treat epilepsy. Use of ACTH to treat epileptic spasms can induce status dystonicus."
GeneReviews explicitly lists sodium valproate and ACTH as agents/circumstances to avoid in BTBGD.
Genetic counseling
Action: Genetic CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Genetic Counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. NCIT:C15240
Families benefit from counseling about autosomal recessive recurrence risk and targeted SLC19A3 testing for relatives.
Show evidence (1 reference)
PMID:27896110 SUPPORT Human Clinical
"early supplementation with biotin and/or thiamine can improve the devastating progression of this condition and allow for appropriate genetic counseling."
Case report explicitly links molecular diagnosis and treatment recognition to genetic counseling.
🔬

Biochemical Markers

1
Blood lactate elevation (INCREASED)
Context: Infantile BTBGD may present with lactic acidosis with encephalopathy, and affected patients can show elevated blood lactate during the diagnostic evaluation.
Pathograph Readouts
Readout Of Lactic acidosis Positive Diagnostic
Elevated blood lactate is the biochemical measurement underlying the lactic acidosis phenotype in infantile BTBGD presentations.
Show evidence (1 reference)
PMID:27896110 SUPPORT Human Clinical
"Biochemical analysis revealed elevated blood lactate at 3.8 mmol/L (nl 0.6-2.2)"
Patient testing directly documents elevated blood lactate.
Show evidence (2 references)
PMID:27896110 SUPPORT Human Clinical
"Four different phenotypes have been described; infantile lactic acidosis with encephalopathy"
Full-text review identifies infantile lactic acidosis with encephalopathy as a recognized presentation.
PMID:27896110 SUPPORT Human Clinical
"Biochemical analysis revealed elevated blood lactate at 3.8 mmol/L (nl 0.6-2.2)"
Patient biochemical testing directly documents elevated lactate.
🔬

Diagnosis

3
Brain MRI for bilateral basal ganglia lesions
Brain MRI helps distinguish BTBGD from other encephalopathies by detecting bilateral caudate, putamen, and other basal ganglia signal abnormalities, sometimes with thalamic and cortical-subcortical involvement.
magnetic resonance imaging procedure NCIT:C16809 NCI Thesaurus (NCIT)
Results: Bilateral basal ganglia lesions or signal abnormalities support BTBGD and should trigger SLC19A3 testing and immediate vitamin therapy.
Show evidence (3 references)
PMID:27905264 SUPPORT Human Clinical
"Children presenting with unexplained encephalopathy and MRI abnormalities including bilateral signal alteration of caudate nucleus and putamen should raise the suspicion for BTBGD"
Review states that this MRI pattern should raise suspicion for BTBGD.
PMID:28677371 SUPPORT Human Clinical
"We confirm that the autopsy and/or MRI of the brain is sufficient to qualify a patient with an unknown neuropathological disorder directly for SLC19A3 mutations testing and a prompt trial of specific treatment."
Neuropathology/MRI study supports MRI as a route to targeted SLC19A3 testing and treatment.
PMID:35532649 SUPPORT Human Clinical
"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"
Adult case report supports broader MRI pattern recognition for BTBGD.
Molecular genetic testing of SLC19A3
Molecular testing confirms biallelic pathogenic SLC19A3 variants and helps distinguish BTBGD from Leigh syndrome or mitochondrial disease mimics.
genetic testing NCIT:C15709 NCI Thesaurus (NCIT)
Results: Biallelic pathogenic SLC19A3 variants establish the molecular diagnosis.
Show evidence (1 reference)
PMID:27896110 SUPPORT Human Clinical
"Whole exome sequencing (WES) was performed at Baylor College of Medicine, Medical Genetics Laboratory and confirmed compound heterozygous frameshift mutations in the SLC19A3 gene in trans"
WES established the molecular diagnosis in a BTBGD patient.
Targeted familial SLC19A3 testing
Once both familial pathogenic variants are known, targeted testing of apparently asymptomatic siblings can identify biallelic relatives before an encephalopathic episode and permit prompt disease-specific management.
genetic testing NCIT:C15709 NCI Thesaurus (NCIT)
Results: Biallelic familial pathogenic variants identify an affected at-risk relative.
Show evidence (2 references)
PMID:24260777 SUPPORT Human Clinical
"It is appropriate to clarify the genetic status of apparently asymptomatic older and younger sibs of an affected individual to identify as early as possible those who would benefit from prompt initiation of treatment with biotin and thiamine"
Current GeneReviews guidance supports presymptomatic testing of at-risk siblings after the familial variants are known.
PMID:37670342 SUPPORT Human Clinical
"three individuals were diagnosed pre-symptomatically during familial targeted genetic screening."
The regional cohort documents actual presymptomatic case identification through familial targeted testing.
📈

Progression

2
Acute/subacute presentation
Age: Infancy to adulthood
The disorder may present as infantile, childhood, or adult Wernicke-like encephalopathy, commonly with acute or subacute worsening after illness or other physiologic stress.
Show evidence (4 references)
ORPHA:65284 SUPPORT Other
"Age of onset: Infancy"
Orphanet records infantile onset.
ORPHA:65284 SUPPORT Other
"Age of onset: Childhood"
Orphanet records childhood onset.
ORPHA:65284 SUPPORT Other
"Age of onset: Adult"
Orphanet records adult onset.
+ 1 more reference
Outcome depends on treatment timing
Age: Any symptomatic age
Delay in recognition and vitamin treatment is associated with severe residual disability or death, while early treatment can stabilize or improve neurologic signs.
Show evidence (2 references)
PMID:27905264 SUPPORT Human Clinical
"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."
Family data directly support the treatment-timing effect on clinical outcome.
PMID:37670342 SUPPORT Human Clinical
"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."
The 21-person regional cohort supplies a quantitative treatment-response estimate and independently links delay with severe residual disease.
📊

Prevalence

1
Worldwide
Point Prevalence ≤0.1 per 100,000 <1 in 1,000,000
Orphanet classifies BTBGD as ultra-rare worldwide.
Show evidence (1 reference)
ORPHA:65284 SUPPORT Other
"<1 / 1 000 000 | Worldwide | Point prevalence | ORPHANET"
Orphanet reports worldwide point prevalence below one per million.
🔀

Differential Diagnoses

1

Conditions with similar clinical presentations that must be differentiated from Biotin-Thiamine-Responsive Basal Ganglia Disease:

Leigh syndrome MONDO:0009723
Overlapping Features BTBGD can mimic Leigh syndrome clinically and radiographically, especially with infantile basal ganglia lesions and lactic-acidosis-like presentations.
Show evidence (1 reference)
PMID:27896110 SUPPORT Human Clinical
"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."
Case report directly identifies Leigh syndrome as an important differential diagnosis.
🧫

Experimental Models

1
KAIMRCi004-A/B patient-derived BTBGD iPSC neural progenitor model IPSC_DERIVED_MODEL
Two patient-derived iPSC clones carrying homozygous SLC19A3 c.1264A>G (p.Thr422Ala) were validated for pluripotency and differentiated into neural progenitors. The lines provide a genetically relevant human neural resource, but the publication did not yet demonstrate a disease-specific transport, metabolic, or injury phenotype.
Homozygous SLC19A3 c.1264A>G (p.Thr422Ala) Unedited patient-derived iPSC clones differentiated to neural progenitors
Organism
human NCBITaxon:9606 NCBI Taxonomy (NCBITaxon) Relation: this experimental model is built in this organism This experimental model is built in human, annotated with Homo sapiens (NCBITaxon:9606). NCBITaxon:9606 is an organism from the NCBI Taxonomy.
Cell source
Peripheral-blood-mononuclear-cell-derived iPSC clones from a 10-year-old female with BTBGD
Culture
iPSC monolayer culture followed by differentiation to central-nervous-system neural progenitors
Publication
PMID:38980565
Show evidence (2 references)
PMID:38980565 SUPPORT In Vitro
"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)."
The report directly identifies the patient source, two clones, and causal genotype.
PMID:38980565 SUPPORT In Vitro
"We have confirmed the pluripotency of the generated iPS lines and successfully differentiated them to neural progenitors."
The publication directly validates pluripotency and neural-progenitor differentiation.
🐁

Animal Models

1
Homozygous total-body Slc19a3tm1Said knockout, with a Slc19a3-null intestine-specific human SLC19A3 transgenic rescue group (SLC19A3int) as a comparator Mus musculus Knockout and tissue-specific rescue
Total-body loss of Slc19a3 lowered circulating and brain thiamine despite an 85 mg/kg thiamine diet and altered the brain metabolome. Intestinal human SLC19A3 expression produced circulating vitamers equivalent to wild-type animals but did not fully normalize brain thiamine. The study supports a tissue-specific requirement for transporter function but models thiamine distribution and metabolism rather than the complete human neurologic syndrome.
Reduced plasma thiamine Reduced brain thiamine Altered brain metabolome
Species
Mus musculus
Genotype
Homozygous total-body Slc19a3tm1Said knockout, with a Slc19a3-null intestine-specific human SLC19A3 transgenic rescue group (SLC19A3int) as a comparator
Background
JAX stock 017343 knockout embryos were crossed with B6D2F1 females to generate the transgenic line; wild-type, knockout, and transgenic littermates were compared.
Alleles
Slc19a3tm1Said (The Jackson Laboratory stock 017343), SLC19A3int (study designation for the intestinal epithelial VIL1-promoter human SLC19A3 transgene; integration site and registered allele symbol were not reported)
Show evidence (3 references)
PMID:37623829 SUPPORT Model Organism
"To evaluate the impact of THTR2 on tissue thiamine status and metabolism, we expressed the human SLC19A3 transgene in the intestine of total body Slc19a3 knockout (KO) mice."
The abstract directly supports the knockout and intestine-specific human transgene comparison; the full methods identify JAX stock 017343 and the intestinal epithelial VIL1 promoter but do not report a registered integration allele.
PMID:37623829 SUPPORT Model Organism
"KO mice had ~two- and ~three-fold lower plasma and brain thiamine levels than WT on the 5× diet."
The knockout directly demonstrates reduced systemic and cerebral thiamine despite the high-thiamine diet.
PMID:37623829 SUPPORT Model Organism
"The loss of THTR2 reduced levels of nucleic acid and amino acid derivatives in the brain."
Untargeted metabolomics connects transporter loss to altered brain metabolism.
{ }

Source YAML

click to show 
name: Biotin-Thiamine-Responsive Basal Ganglia Disease
creation_date: "2026-05-07T13:45:22Z"
description: >-
  Biotin-thiamine-responsive basal ganglia disease is a rare autosomal
  recessive neurometabolic disorder caused by biallelic SLC19A3 variants that
  impair thiamine transporter 2 function. It typically presents with subacute
  encephalopathy, seizures, dysarthria or dysphagia, and movement disorder,
  often after febrile illness, with characteristic bilateral basal ganglia MRI
  abnormalities that may extend to thalamic, cortical, and subcortical regions.
  Early high-dose thiamine and biotin can reverse symptoms and prevent
  progression, whereas delayed diagnosis is associated with severe neurologic
  disability or death.
category: Mendelian
disease_term:
  preferred_term: biotin-thiamine-responsive basal ganglia disease
  term:
    id: MONDO:0011841
    label: biotin-responsive basal ganglia disease
parents:
- Basal Ganglia Disorder
- Hereditary Neurological Disease
- Neurometabolic Disorder
classifications:
  harrisons_chapter:
  - classification_value: NEUROLOGIC
    evidence:
    - reference: ORPHA:65284
      reference_title: "Biotin-thiamine-responsive basal ganglia disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        A rare genetic neurological disorder characterized by subacute
        encephalopathy with confusion, seizures, and movement disorder, often
        following a history of febrile illness.
      explanation: >-
        The structured disease record places BTBGD within genetic neurologic
        disease, matching the Harrison's neurologic classification.
synonyms:
- BBGD
- BTBGD
- BTRBGD
- Biotin-responsive basal ganglia disease
- Thiamine-responsive encephalopathy
- Thiamine metabolism dysfunction syndrome 2
notes: >-
  ORPHA:65284 is the primary structured disease record used for the disease
  scope. ORPHA:199348 is an older/narrower thiamine-responsive encephalopathy
  record that maps to the same MONDO concept and supports the SLC19A3-gene and
  thiamine-responsive phenotype relationship. Phenotype frequencies are not
  asserted because the cached Orphanet records do not provide HPO frequency
  rows and the cited clinical literature is heterogeneous.
mappings:
  mondo_mappings:
  - term:
      id: MONDO:0011841
      label: biotin-responsive basal ganglia disease
    mapping_predicate: skos:exactMatch
    mapping_source: Orphanet ORPHA:65284
    mapping_justification: >-
      ORPHA:65284 maps exactly to MONDO:0011841 and defines the current
      biotin-thiamine-responsive basal ganglia disease scope.
external_assertions:
- name: Orphanet biotin-thiamine-responsive basal ganglia disease record
  source: Orphanet
  assertion_type: structured_disease_record
  external_id: ORPHA:65284
  url: http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=65284
  description: >-
    Orphanet's ORPHA:65284 structured record supplies the disease definition,
    synonyms, inheritance, onset, prevalence, disease-gene assertion, and
    exact MONDO mapping used in this entry.
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "MONDO:0011841 | Exact"
    explanation: Orphanet maps ORPHA:65284 exactly to the MONDO concept used here.
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "SLC19A3 | solute carrier family 19 member 3 | hgnc:16266 | Disease-causing germline mutation(s) in"
    explanation: Orphanet records SLC19A3 as the disease-causing gene for ORPHA:65284.
- name: Orphanet thiamine-responsive encephalopathy record
  source: Orphanet
  assertion_type: structured_disease_record
  external_id: ORPHA:199348
  url: http://www.orpha.net/consor/cgi-bin/OC_Exp.php?lng=en&Expert=199348
  description: >-
    ORPHA:199348 is a thiamine-responsive encephalopathy record with SLC19A3
    and OMIM:607483 cross-references that overlaps the BTBGD disease concept.
  evidence:
  - reference: ORPHA:199348
    reference_title: "Thiamine-responsive encephalopathy"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Thiamine-responsive encephalopathy is a Wernicke-like encephalopathy characterized by seizures responsive to high doses of thiamine."
    explanation: The older Orphanet record supports the thiamine-responsive encephalopathy phenotype.
  - reference: ORPHA:199348
    reference_title: "Thiamine-responsive encephalopathy"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "SLC19A3 | solute carrier family 19 member 3 | hgnc:16266 | Disease-causing germline mutation(s) in"
    explanation: ORPHA:199348 also records SLC19A3 as the disease-causing gene.
definitions:
- name: Treatable SLC19A3-related basal ganglia encephalopathy
  definition_type: OTHER
  description: >-
    BTBGD is defined as an SLC19A3-related, treatable encephalopathy with
    confusion, seizures, movement disorder, and bilateral basal ganglia lesions.
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness.
    explanation: Orphanet provides the concise disease definition and core clinical presentation.
  - reference: PMID:27905264
    reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Biotin-thiamine-responsive basal ganglia disease (BTBGD) is an autosomal recessive neurometabolic disorder caused by mutations in the SLC19A3 gene.
    explanation: A family study and literature review defines BTBGD by its SLC19A3 genetic cause and neurometabolic phenotype.
has_subtypes:
- name: Early-infantile BTBGD
  display_name: Early-infantile biotin-thiamine-responsive basal ganglia disease
  classification: age_at_presentation
  description: >-
    Presentation before age three months, with vomiting, feeding difficulty,
    encephalopathy, hypotonia, seizures, and respiratory failure. This form has
    a poorer prognosis than classic childhood and adult presentations, including
    despite vitamin treatment in some infants.
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Early-infantile BTBGD presents before age three months with vomiting,
      feeding difficulties, encephalopathy, hypotonia, seizures, and respiratory
      failure.
    explanation: >-
      The current GeneReviews summary defines the early-infantile presentation
      and its core manifestations.
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Prompt administration of biotin and thiamine early in the disease course
      results in partial or complete improvement within days in classic and
      adult BTBGD; however, most infants with early-infantile BTBGD have a poor
      outcome.
    explanation: >-
      GeneReviews directly supports the poorer prognosis of the early-infantile
      presentation despite the treatability of later presentations.
- name: Classic childhood BTBGD
  display_name: Classic childhood biotin-thiamine-responsive basal ganglia disease
  classification: age_at_presentation
  description: >-
    Usually presents between ages three and ten years with recurrent subacute
    encephalopathy, confusion, seizures, ataxia, cranial motor abnormalities,
    dysphagia, dystonia, and rigidity. Febrile illness, mild trauma, or other
    stress commonly precedes an episode.
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Classic BTBGD presents between ages three and ten years with recurrent
      subacute encephalopathy manifesting as confusion, seizures, ataxia,
      supranuclear facial palsy, external ophthalmoplegia, and/or dysphagia that,
      if left untreated, can eventually lead to coma and even death.
    explanation: >-
      The current GeneReviews summary defines the age range and clinical
      spectrum of classic BTBGD.
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Dystonia and cogwheel rigidity are nearly always present; hyperreflexia,
      ankle clonus, and Babinski responses are common. Hemiparesis or
      quadriparesis may be seen. Episodes are often triggered by febrile illness
      or mild trauma or stress.
    explanation: >-
      GeneReviews supports the movement-disorder manifestations and common
      physiologic-stress triggers included in the classic presentation.
- name: Adult Wernicke-like BTBGD
  display_name: Adult Wernicke-like biotin-thiamine-responsive basal ganglia disease
  classification: age_at_presentation
  description: >-
    A rare presentation after age ten years with acute status epilepticus,
    ataxia, nystagmus, diplopia, or ophthalmoplegia. The published clinical base
    is much smaller than for childhood BTBGD.
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Adult Wernicke-like encephalopathy BTBGD, described in three individuals
      to date, presents after age ten years with acute onset of status
      epilepticus, ataxia, nystagmus, diplopia, and ophthalmoplegia.
    explanation: >-
      GeneReviews defines the adult presentation and explicitly conveys its
      limited case base.
inheritance:
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    BTBGD is caused by biallelic pathogenic variants in SLC19A3. When both
    parents are heterozygous, each sibling has a 25% chance of being affected
    at conception.
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Autosomal recessive"
    explanation: Orphanet records autosomal recessive inheritance.
  - reference: PMID:36657988
    reference_title: "Child Neurology: Infantile Biotin Thiamine Responsive Basal Ganglia Disease: Case Report and Brief Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Biotin thiamine responsive basal ganglia disease (BTRBGD) is an inherited autosomal recessive disorder that results from the inability of thiamine to cross the blood-brain barrier.
    explanation: Clinical case report and review states the autosomal recessive inheritance and thiamine-transport basis.
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      If both parents are known to be heterozygous for an SLC19A3 pathogenic
      variant, each sib of an affected individual has at conception a 25%
      chance of being affected, a 50% chance of being an asymptomatic carrier,
      and a 25% chance of being unaffected and not a carrier.
    explanation: >-
      GeneReviews provides the explicit autosomal-recessive recurrence risks
      requested in review.
prevalence:
- population: Worldwide
  measure_type: POINT_PREVALENCE
  prevalence_class: BELOW_1_IN_1000000
  rate_high: 0.1
  percentage: <1 per 1,000,000
  notes: Orphanet classifies BTBGD as ultra-rare worldwide.
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "<1 / 1 000 000 | Worldwide | Point prevalence | ORPHANET"
    explanation: Orphanet reports worldwide point prevalence below one per million.
progression:
- phase: Acute/subacute presentation
  age_range: Infancy to adulthood
  notes: >-
    The disorder may present as infantile, childhood, or adult Wernicke-like
    encephalopathy, commonly with acute or subacute worsening after illness or
    other physiologic stress.
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Age of onset: Infancy"
    explanation: Orphanet records infantile onset.
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Age of onset: Childhood"
    explanation: Orphanet records childhood onset.
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Age of onset: Adult"
    explanation: Orphanet records adult onset.
  - reference: PMID:36657988
    reference_title: "Child Neurology: Infantile Biotin Thiamine Responsive Basal Ganglia Disease: Case Report and Brief Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      BTRBGD can present as an infantile form, classical childhood form, or adult Wernicke-like encephalopathy.
    explanation: Review summarizes the three recognized age-related presentations.
- phase: Outcome depends on treatment timing
  age_range: Any symptomatic age
  notes: >-
    Delay in recognition and vitamin treatment is associated with severe
    residual disability or death, while early treatment can stabilize or improve
    neurologic signs.
  evidence:
  - reference: PMID:27905264
    reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      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.
    explanation: Family data directly support the treatment-timing effect on clinical outcome.
  - reference: PMID:37670342
    reference_title: "Biotin-thiamine responsive basal ganglia disease: a retrospective review of the clinical, radiological and molecular findings of cases in Kuwait with novel variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      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.
    explanation: >-
      The 21-person regional cohort supplies a quantitative treatment-response
      estimate and independently links delay with severe residual disease.
genetic:
- name: Biallelic SLC19A3 pathogenic variants
  gene_term:
    preferred_term: SLC19A3
    term:
      id: hgnc:16266
      label: SLC19A3
  association: Biallelic SLC19A3 pathogenic variants cause BTBGD.
  relationship_type: CAUSATIVE
  variant_origin: GERMLINE
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "SLC19A3 | solute carrier family 19 member 3 | hgnc:16266 | Disease-causing germline mutation(s) in"
    explanation: Orphanet records SLC19A3 as disease-causing.
  - reference: PMID:27896110
    reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Whole exome sequencing (WES) was performed at Baylor College of Medicine, Medical Genetics Laboratory and confirmed compound heterozygous frameshift mutations in the SLC19A3 gene in trans
    explanation: Patient sequencing identified biallelic SLC19A3 frameshift variants in trans.
  variants:
  - name: SLC19A3 c.1264A>G (p.Thr422Ala)
    description: >-
      Homozygous p.Thr422Ala is a Saudi founder variant and accounted for most
      cases in a 21-person Kuwait cohort. Structural work places Thr422 in the
      outer transporter region and supports impaired thiamine affinity and
      transport, but this regional enrichment should not be generalized to all
      ancestries.
    evidence:
    - reference: PMID:37670342
      reference_title: "Biotin-thiamine responsive basal ganglia disease: a retrospective review of the clinical, radiological and molecular findings of cases in Kuwait with novel variants."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        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.
      explanation: >-
        The regional cohort identifies the founder allele and distinguishes it
        from two newly observed homozygous missense variants.
    - reference: PMID:39358356
      reference_title: Structural basis of thiamine transport and drug recognition by SLC19A3.
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Structural changes in this region might explain the loss of affinity and
        transport activity of the Thr422Ala mutant.
      explanation: >-
        Cryo-EM-guided interpretation supports a structural basis for impaired
        transport but does not by itself establish clinical severity.
pathophysiology:
- name: SLC19A3 thiamine transporter deficiency
  description: >-
    Pathogenic SLC19A3 variants reduce thiamine transporter 2 function,
    limiting thiamine transport into and within the central nervous system.
  mechanism_confidence: ESTABLISHED
  biological_scale: MOLECULAR
  genes:
  - preferred_term: SLC19A3
    term:
      id: hgnc:16266
      label: SLC19A3
  molecular_functions:
  - preferred_term: thiamine transmembrane transporter activity
    term:
      id: GO:0015234
      label: thiamine transmembrane transporter activity
    modifier: DECREASED
  biological_processes:
  - preferred_term: thiamine transport
    term:
      id: GO:0015888
      label: thiamine transport
    modifier: DECREASED
  locations:
  - preferred_term: blood brain barrier
    term:
      id: UBERON:0000120
      label: blood brain barrier
  evidence:
  - reference: PMID:24372704
    reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      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.
    explanation: Cell/tissue study states the causal gene and thiamine transporter 2 function.
  - reference: PMID:36657988
    reference_title: "Child Neurology: Infantile Biotin Thiamine Responsive Basal Ganglia Disease: Case Report and Brief Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Biotin thiamine responsive basal ganglia disease (BTRBGD) is an inherited autosomal recessive disorder that results from the inability of thiamine to cross the blood-brain barrier.
    explanation: Clinical review links disease mechanism to impaired thiamine entry across the blood-brain barrier.
  - reference: PMID:39358356
    reference_title: Structural basis of thiamine transport and drug recognition by SLC19A3.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Here, we report seven cryo-electron microscopy (cryo-EM) structures of the
      human thiamine transporter SLC19A3 in complex with various ligands.
      Conformation-specific nanobodies enable us to capture different states of
      SLC19A3's transport cycle, revealing the molecular details of thiamine
      recognition and transport.
    explanation: >-
      Structural and functional work directly establishes the molecular
      substrate-recognition and transport cycle represented by this node.
  downstream:
  - target: Stress-triggered cerebral thiamine-transport failure
    causal_link_type: DIRECT
    description: Mutant SLC19A3 limits the adaptive thiamine-transport response needed during physiologic stress.
    evidence:
    - reference: PMID:24372704
      reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        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.
      explanation: Patient fibroblast data directly support impaired stress-induced SLC19A3 upregulation downstream of the transporter defect.
    - reference: PMID:24372704
      reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        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.
      explanation: Authors connect mutant neuronal-cell stress adaptation to encephalopathic episodes.
- name: Stress-triggered cerebral thiamine-transport failure
  description: >-
    Febrile illness, acidosis, hypoxia, and other stressors fail to induce
    adequate SLC19A3 upregulation in patient cells, reducing adaptive thiamine
    availability when neuronal demand is high.
  mechanism_confidence: PROVISIONAL
  biological_scale: CELLULAR
  biological_processes:
  - preferred_term: cellular response to hypoxia
    term:
      id: GO:0071456
      label: cellular response to hypoxia
    modifier: ABNORMAL
  - preferred_term: thiamine transport
    term:
      id: GO:0015888
      label: thiamine transport
    modifier: DECREASED
  locations:
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  evidence:
  - reference: PMID:24372704
    reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      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.
    explanation: Patient fibroblast data show failure of stress-induced SLC19A3 upregulation.
  - reference: PMID:24372704
    reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      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.
    explanation: Authors connect impaired stress adaptation to encephalopathic episodes.
  downstream:
  - target: Basal ganglia and gray-matter injury
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Cerebral thiamine-transport failure produces Wernicke-like injury with basal ganglia vulnerability.
    evidence:
    - reference: PMID:24372704
      reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        These results demonstrate ubiquitously reduced thiamine transporter function in the cerebral gray matter, and neuropathological alterations similar to Wernicke's disease in BTBGD.
      explanation: Human brain/tissue findings support gray-matter thiamine-transporter failure and Wernicke-like neuropathology.
  - target: Lactic acidosis
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Severe infantile presentations may include elevated lactate/lactic acidosis during metabolic decompensation.
    intermediate_mechanisms:
    - metabolic decompensation during infantile encephalopathic presentations
    evidence:
    - reference: PMID:27896110
      reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Four different phenotypes have been described; infantile lactic acidosis with encephalopathy
      explanation: Clinical review links lactic acidosis with the infantile encephalopathic BTBGD presentation, supporting an indirect edge.
    - reference: PMID:27896110
      reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Biochemical analysis revealed elevated blood lactate at 3.8 mmol/L (nl 0.6-2.2)
      explanation: Patient biochemical testing documents lactate elevation during evaluation of BTBGD.
- name: Basal ganglia and gray-matter injury
  description: >-
    Impaired cerebral thiamine transport injures basal ganglia and other gray
    matter regions, producing bilateral basal ganglia lesions, Wernicke-like
    pathology, seizures, encephalopathy, and movement disorder.
  mechanism_confidence: ESTABLISHED
  biological_scale: TISSUE
  cell_types:
  - preferred_term: neuron
    term:
      id: CL:0000540
      label: neuron
  locations:
  - preferred_term: basal ganglion
    term:
      id: UBERON:0002420
      label: basal ganglion
  - preferred_term: brain
    term:
      id: UBERON:0000955
      label: brain
  evidence:
  - reference: PMID:24372704
    reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      These results demonstrate ubiquitously reduced thiamine transporter function in the cerebral gray matter, and neuropathological alterations similar to Wernicke's disease in BTBGD.
    explanation: Human brain tissue findings support reduced transporter function and Wernicke-like gray-matter pathology.
  - reference: PMID:28677371
    reference_title: "Neuropathological characteristics of the brain in two patients with SLC19A3 mutations related to the biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The central nervous system lesions found in the patients displayed almost clearly a specific pattern for SLC19A3 defect, as previously proposed in diagnostic criteria.
    explanation: Neuropathology/MRI study supports a specific SLC19A3-related CNS lesion pattern.
  downstream:
  - target: Subacute encephalopathy
    causal_link_type: DIRECT
    description: Cerebral gray-matter injury manifests clinically as acute or subacute encephalopathy.
    evidence:
    - reference: ORPHA:65284
      reference_title: "Biotin-thiamine-responsive basal ganglia disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness.
      explanation: Orphanet defines BTBGD by subacute encephalopathy in the setting of this basal ganglia disease.
  - target: Confusion
    causal_link_type: DIRECT
    description: The encephalopathic gray-matter injury state includes confusion or altered mental status.
    evidence:
    - reference: ORPHA:65284
      reference_title: "Biotin-thiamine-responsive basal ganglia disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness.
      explanation: Orphanet lists confusion as part of the BTBGD encephalopathic presentation.
  - target: Cognitive impairment
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Adult Wernicke-like BTBGD gray-matter injury can present with rapidly progressive cognitive impairment.
    evidence:
    - reference: PMID:35532649
      reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We report a 49-year-old lady presenting with rapidly progressive
        cognitive impairment, seizures, hypersomnolence, ataxia, and generalized
        dystonia of 3 weeks duration.
      explanation: >-
        A genetically confirmed adult case links rapidly progressive cognitive
        impairment to the acute CNS disease state.
  - target: Hypersomnolence
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: The acute encephalopathic CNS injury state can include hypersomnolence during BTBGD episodes.
    evidence:
    - reference: PMID:35532649
      reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We report a 49-year-old lady presenting with rapidly progressive
        cognitive impairment, seizures, hypersomnolence, ataxia, and generalized
        dystonia of 3 weeks duration.
      explanation: >-
        The adult case documents hypersomnolence during a rapidly progressive
        neurologic presentation.
  - target: Seizures
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Injured cerebral networks during BTBGD episodes are associated with seizures.
    evidence:
    - reference: ORPHA:65284
      reference_title: "Biotin-thiamine-responsive basal ganglia disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness.
      explanation: Orphanet lists seizures within the defining encephalopathic presentation.
    - reference: PMID:35532649
      reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration.
      explanation: Adult BTBGD case documents seizures together with acute neurologic deterioration.
  - target: Movement disorder and dystonia
    causal_link_type: DIRECT
    description: Basal ganglia injury produces extrapyramidal movement disorder and dystonia.
    evidence:
    - reference: ORPHA:65284
      reference_title: "Biotin-thiamine-responsive basal ganglia disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness.
      explanation: Orphanet identifies movement disorder as part of the defining basal ganglia disease presentation.
    - reference: PMID:35532649
      reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration.
      explanation: Adult BTBGD case documents generalized dystonia during the episode.
  - target: Cogwheel rigidity
    causal_link_type: DIRECT
    description: Basal ganglia dysfunction in classic BTBGD produces extrapyramidal cogwheel rigidity.
    evidence:
    - reference: PMID:24260777
      reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "Dystonia and cogwheel rigidity are nearly always present"
      explanation: GeneReviews states that cogwheel rigidity is nearly always present in classic BTBGD.
  - target: Hyperreflexia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: BTBGD can include corticospinal or upper-motor-neuron signs such as hyperreflexia during classic presentations.
    evidence:
    - reference: PMID:24260777
      reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "hyperreflexia, ankle clonus, and Babinski responses are common."
      explanation: GeneReviews lists hyperreflexia among common classic BTBGD neurologic signs.
  - target: Ankle clonus
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Corticospinal involvement in classic BTBGD can manifest as ankle clonus.
    evidence:
    - reference: PMID:24260777
      reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "hyperreflexia, ankle clonus, and Babinski responses are common."
      explanation: >-
        GeneReviews places ankle clonus among the common corticospinal signs in
        classic BTBGD.
  - target: Babinski sign
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Corticospinal involvement in classic BTBGD can manifest as Babinski responses.
    evidence:
    - reference: PMID:24260777
      reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: "hyperreflexia, ankle clonus, and Babinski responses are common."
      explanation: >-
        GeneReviews places Babinski responses among the common corticospinal
        signs in classic BTBGD.
  - target: Dysphagia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: BTBGD encephalopathic CNS injury can include bulbar dysfunction with dysphagia.
    evidence:
    - reference: PMID:27905264
      reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The disease is characterized by subacute encephalopathy with confusion, dysphagia, dysarthria, and seizures.
      explanation: Clinical review links dysphagia to the BTBGD encephalopathic presentation.
  - target: Dysarthria
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: BTBGD encephalopathic CNS injury can include dysarthria.
    evidence:
    - reference: PMID:27905264
      reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The disease is characterized by subacute encephalopathy with confusion, dysphagia, dysarthria, and seizures.
      explanation: Clinical review links dysarthria to the BTBGD encephalopathic presentation.
  - target: Ataxia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: Wernicke-like gray-matter involvement can present with ataxia in adult BTBGD.
    evidence:
    - reference: PMID:35532649
      reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration.
      explanation: Adult BTBGD case documents ataxia with rapidly progressive neurologic involvement.
  - target: Bilateral basal ganglia MRI abnormalities
    causal_link_type: DIRECT
    description: Basal ganglia lesions are visible as characteristic bilateral MRI signal abnormalities.
    evidence:
    - reference: ORPHA:65284
      reference_title: "Biotin-thiamine-responsive basal ganglia disease"
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "Imaging may reveal bilateral lesions in the basal ganglia."
      explanation: Orphanet directly supports bilateral basal ganglia imaging abnormalities.
    - reference: PMID:35532649
      reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        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
      explanation: Adult case report documents MRI-visible basal ganglia and broader gray-matter injury.
histopathology:
- name: Necrotic and hemorrhagic basal ganglia lesions
  description: >-
    Post-mortem BTBGD brain tissue can show mixed acute, subacute, and chronic
    neuropathologic injury with cystic/necrotic putamen lesions, hemorrhagic
    caudate lesions, cortical-layer hemorrhage, and Wernicke-like gray-matter
    alterations.
  context: SLC19A3-mutant central nervous system tissue
  evidence:
  - reference: PMID:24372704
    reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      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.
    explanation: Post-mortem human brain analysis documents necrotic and hemorrhagic basal ganglia/cortical lesions.
  - reference: PMID:24372704
    reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      neuropathological alterations similar to Wernicke's disease in BTBGD.
    explanation: The same study links BTBGD pathology to Wernicke-like gray-matter injury.
- name: SLC19A3-specific central nervous system lesion pattern
  description: >-
    Neuropathology and MRI studies support a recognizable central nervous
    system lesion pattern in patients with SLC19A3 variants.
  context: Brain autopsy and MRI correlation
  evidence:
  - reference: PMID:28677371
    reference_title: "Neuropathological characteristics of the brain in two patients with SLC19A3 mutations related to the biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The central nervous system lesions found in the patients displayed almost clearly a specific pattern for SLC19A3 defect, as previously proposed in diagnostic criteria.
    explanation: Dedicated neuropathology/MRI study supports a specific SLC19A3-related CNS lesion pattern.
phenotypes:
- category: Neurological
  name: Subacute encephalopathy
  description: >-
    Acute or subacute encephalopathy with confusion or altered mental status is
    the core clinical presentation.
  phenotype_term:
    preferred_term: Encephalopathy
    term:
      id: HP:0001298
      label: Encephalopathy
    temporality: SUBACUTE
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness.
    explanation: Orphanet definition directly identifies subacute encephalopathy.
  - reference: PMID:27905264
    reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The disease is characterized by subacute encephalopathy with confusion, dysphagia, dysarthria, and seizures.
    explanation: Clinical review identifies subacute encephalopathy with associated neurologic features.
- category: Neurological
  name: Confusion
  description: Confusion accompanies the encephalopathic episodes.
  phenotype_term:
    preferred_term: Confusion
    term:
      id: HP:0001289
      label: Confusion
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness.
    explanation: Orphanet lists confusion within the defining presentation.
- category: Neurological
  name: Seizures
  description: Seizures are a common component of acute BTBGD episodes.
  phenotype_term:
    preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness.
    explanation: Orphanet lists seizures in the defining presentation.
  - reference: PMID:35532649
    reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration.
    explanation: Adult BTBGD case confirms seizures in a genetically confirmed patient.
- category: Neurological
  name: Movement disorder and dystonia
  description: >-
    Movement disorder is part of the defining phenotype and may include
    generalized dystonia.
  phenotype_term:
    preferred_term: Dystonia
    term:
      id: HP:0001332
      label: Dystonia
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      A rare genetic neurological disorder characterized by subacute encephalopathy with confusion, seizures, and movement disorder, often following a history of febrile illness.
    explanation: Orphanet lists movement disorder in the defining presentation; dystonia is a specific movement-disorder manifestation supported by the clinical case.
  - reference: PMID:35532649
    reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration.
    explanation: Genetically confirmed adult BTBGD case documents generalized dystonia.
- category: Neurological
  name: Cogwheel rigidity
  description: >-
    Cogwheel rigidity is nearly always present in classic BTBGD, consistent
    with extrapyramidal basal ganglia dysfunction.
  phenotype_term:
    preferred_term: Cogwheel rigidity
    term:
      id: HP:0002396
      label: Cogwheel rigidity
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Dystonia and cogwheel rigidity are nearly always present"
    explanation: GeneReviews states that cogwheel rigidity is nearly always present in classic BTBGD.
- category: Neurological
  name: Hyperreflexia
  description: Hyperreflexia is a common neurologic sign in classic BTBGD.
  phenotype_term:
    preferred_term: Hyperreflexia
    term:
      id: HP:0001347
      label: Hyperreflexia
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "hyperreflexia, ankle clonus, and Babinski responses are common."
    explanation: GeneReviews lists hyperreflexia among common classic BTBGD neurologic signs.
- category: Neurological
  name: Dysphagia
  description: Dysphagia can occur during BTBGD encephalopathic presentations.
  phenotype_term:
    preferred_term: Dysphagia
    term:
      id: HP:0002015
      label: Dysphagia
  evidence:
  - reference: PMID:27905264
    reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The disease is characterized by subacute encephalopathy with confusion, dysphagia, dysarthria, and seizures.
    explanation: Clinical review lists dysphagia among characteristic findings.
- category: Neurological
  name: Dysarthria
  description: Dysarthria can occur during BTBGD encephalopathic presentations.
  phenotype_term:
    preferred_term: Dysarthria
    term:
      id: HP:0001260
      label: Dysarthria
  evidence:
  - reference: PMID:27905264
    reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The disease is characterized by subacute encephalopathy with confusion, dysphagia, dysarthria, and seizures.
    explanation: Clinical review lists dysarthria among characteristic findings.
- category: Neurological
  name: Ataxia
  description: Ataxia has been reported in adult Wernicke-like BTBGD presentations.
  phenotype_term:
    preferred_term: Ataxia
    term:
      id: HP:0001251
      label: Ataxia
  evidence:
  - reference: PMID:35532649
    reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration.
    explanation: Genetically confirmed adult BTBGD case documents ataxia.
- category: Metabolic
  name: Lactic acidosis
  description: >-
    Infantile BTBGD presentations may include lactic acidosis or elevated blood
    lactate during encephalopathic decompensation.
  phenotype_term:
    preferred_term: Lactic acidosis
    term:
      id: HP:0003128
      label: Lactic acidosis
  evidence:
  - reference: PMID:27896110
    reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Four different phenotypes have been described; infantile lactic acidosis with encephalopathy
    explanation: Full-text review identifies infantile lactic acidosis with encephalopathy as one recognized BTBGD presentation.
  - reference: PMID:27896110
    reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Biochemical analysis revealed elevated blood lactate at 3.8 mmol/L (nl 0.6-2.2)
    explanation: Patient biochemical testing documents elevated blood lactate.
- category: Radiographic
  name: Bilateral basal ganglia MRI abnormalities
  description: >-
    Brain MRI commonly shows bilateral signal abnormalities or lesions in the
    caudate nucleus, putamen, globus pallidus, and related basal ganglia
    structures, and may also show thalamic, cortical, subcortical white matter,
    brainstem, cerebellar, or cervical-spine involvement.
  phenotype_term:
    preferred_term: Abnormal basal ganglia morphology
    term:
      id: HP:0002134
      label: Abnormal basal ganglia morphology
  evidence:
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Imaging may reveal bilateral lesions in the basal ganglia."
    explanation: Orphanet describes the bilateral basal ganglia imaging pattern.
  - reference: PMID:27905264
    reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Children presenting with unexplained encephalopathy and MRI abnormalities including bilateral signal alteration of caudate nucleus and putamen should raise the suspicion for BTBGD
    explanation: Review highlights bilateral caudate and putamen signal alteration as a diagnostic clue.
  - reference: PMID:35532649
    reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      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
    explanation: Adult case report documents thalamic, cortical, and subcortical involvement in addition to basal ganglia abnormalities.
  - reference: PMID:27896110
    reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Typical MRI findings include cortical, subcortical white matter lesions, and bilateral abnormal signal intensity in the basal ganglia with less frequent involvement of thalami, brain stem, cerebellum and cervical spine
    explanation: Full-text review summarizes broader MRI involvement beyond the basal ganglia.
- category: Neurological
  name: Cognitive impairment
  description: >-
    Rapidly progressive cognitive impairment can be a prominent feature,
    particularly in adult Wernicke-like BTBGD presentations.
  phenotype_term:
    preferred_term: Cognitive impairment
    term:
      id: HP:0100543
      label: Cognitive impairment
  evidence:
  - reference: PMID:35532649
    reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration.
    explanation: Genetically confirmed adult BTBGD case documents rapidly progressive cognitive impairment.
- category: Neurological
  name: Hypersomnolence
  description: >-
    Excessive sleepiness can accompany the acute encephalopathic presentation
    of BTBGD.
  phenotype_term:
    preferred_term: Hypersomnolence
    term:
      id: HP:0002329
      label: Drowsiness
  evidence:
  - reference: PMID:35532649
    reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We report a 49-year-old lady presenting with rapidly progressive cognitive impairment, seizures, hypersomnolence, ataxia, and generalized dystonia of 3 weeks duration.
    explanation: Genetically confirmed adult BTBGD case documents hypersomnolence during the acute episode.
- category: Neurological
  name: Ankle clonus
  description: >-
    Ankle clonus is a common upper-motor-neuron sign in classic BTBGD.
  phenotype_term:
    preferred_term: Ankle clonus
    term:
      id: HP:0011448
      label: Ankle clonus
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "hyperreflexia, ankle clonus, and Babinski responses are common."
    explanation: GeneReviews lists ankle clonus among common classic BTBGD neurologic signs.
- category: Neurological
  name: Babinski sign
  description: >-
    Extensor plantar responses (Babinski sign) are a common corticospinal sign
    in classic BTBGD.
  phenotype_term:
    preferred_term: Babinski sign
    term:
      id: HP:0003487
      label: Babinski sign
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "hyperreflexia, ankle clonus, and Babinski responses are common."
    explanation: GeneReviews lists Babinski responses among common classic BTBGD neurologic signs.
biochemical:
- name: Blood lactate elevation
  presence: INCREASED
  context: >-
    Infantile BTBGD may present with lactic acidosis with encephalopathy, and
    affected patients can show elevated blood lactate during the diagnostic
    evaluation.
  biomarker_term:
    preferred_term: lactate
    term:
      id: CHEBI:24996
      label: lactate
  readouts:
  - target: Lactic acidosis
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: Elevated blood lactate is the biochemical measurement underlying the lactic acidosis phenotype in infantile BTBGD presentations.
    evidence:
    - reference: PMID:27896110
      reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Biochemical analysis revealed elevated blood lactate at 3.8 mmol/L (nl 0.6-2.2)
      explanation: Patient testing directly documents elevated blood lactate.
  evidence:
  - reference: PMID:27896110
    reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Four different phenotypes have been described; infantile lactic acidosis with encephalopathy
    explanation: Full-text review identifies infantile lactic acidosis with encephalopathy as a recognized presentation.
  - reference: PMID:27896110
    reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Biochemical analysis revealed elevated blood lactate at 3.8 mmol/L (nl 0.6-2.2)
    explanation: Patient biochemical testing directly documents elevated lactate.
diagnosis:
- name: Brain MRI for bilateral basal ganglia lesions
  description: >-
    Brain MRI helps distinguish BTBGD from other encephalopathies by detecting
    bilateral caudate, putamen, and other basal ganglia signal abnormalities,
    sometimes with thalamic and cortical-subcortical involvement.
  diagnosis_term:
    preferred_term: magnetic resonance imaging procedure
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  results: Bilateral basal ganglia lesions or signal abnormalities support BTBGD and should trigger SLC19A3 testing and immediate vitamin therapy.
  evidence:
  - reference: PMID:27905264
    reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Children presenting with unexplained encephalopathy and MRI abnormalities including bilateral signal alteration of caudate nucleus and putamen should raise the suspicion for BTBGD
    explanation: Review states that this MRI pattern should raise suspicion for BTBGD.
  - reference: PMID:28677371
    reference_title: "Neuropathological characteristics of the brain in two patients with SLC19A3 mutations related to the biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We confirm that the autopsy and/or MRI of the brain is sufficient to qualify a patient with an unknown neuropathological disorder directly for SLC19A3 mutations testing and a prompt trial of specific treatment.
    explanation: Neuropathology/MRI study supports MRI as a route to targeted SLC19A3 testing and treatment.
  - reference: PMID:35532649
    reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      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
    explanation: Adult case report supports broader MRI pattern recognition for BTBGD.
- name: Molecular genetic testing of SLC19A3
  description: >-
    Molecular testing confirms biallelic pathogenic SLC19A3 variants and helps
    distinguish BTBGD from Leigh syndrome or mitochondrial disease mimics.
  diagnosis_term:
    preferred_term: genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  results: Biallelic pathogenic SLC19A3 variants establish the molecular diagnosis.
  evidence:
  - reference: PMID:27896110
    reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Whole exome sequencing (WES) was performed at Baylor College of Medicine, Medical Genetics Laboratory and confirmed compound heterozygous frameshift mutations in the SLC19A3 gene in trans
    explanation: WES established the molecular diagnosis in a BTBGD patient.
- name: Targeted familial SLC19A3 testing
  description: >-
    Once both familial pathogenic variants are known, targeted testing of
    apparently asymptomatic siblings can identify biallelic relatives before an
    encephalopathic episode and permit prompt disease-specific management.
  diagnosis_term:
    preferred_term: genetic testing
    term:
      id: NCIT:C15709
      label: Genetic Testing
  results: Biallelic familial pathogenic variants identify an affected at-risk relative.
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It is appropriate to clarify the genetic status of apparently asymptomatic
      older and younger sibs of an affected individual to identify as early as
      possible those who would benefit from prompt initiation of treatment with
      biotin and thiamine
    explanation: >-
      Current GeneReviews guidance supports presymptomatic testing of at-risk
      siblings after the familial variants are known.
  - reference: PMID:37670342
    reference_title: "Biotin-thiamine responsive basal ganglia disease: a retrospective review of the clinical, radiological and molecular findings of cases in Kuwait with novel variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      three individuals were diagnosed pre-symptomatically during familial
      targeted genetic screening.
    explanation: >-
      The regional cohort documents actual presymptomatic case identification
      through familial targeted testing.
treatments:
- name: High-dose thiamine and biotin supplementation
  description: >-
    High-dose oral thiamine and biotin should begin as early as possible when
    BTBGD is suspected and continue lifelong. During acute decompensation,
    thiamine may be doubled and given intravenously. Clinical support comes
    from observational cohorts and case series; the independent contribution
    of biotin to the combination remains mechanistically unresolved.
  action_category: THERAPEUTIC
  treatment_term:
    preferred_term: vitamin supplementation
    term:
      id: NCIT:C15425
      label: Nutritional Supplementation
    therapeutic_agent:
    - preferred_term: thiamine
      term:
        id: CHEBI:18385
        label: thiamine(1+)
    - preferred_term: biotin
      term:
        id: CHEBI:15956
        label: biotin
  target_mechanisms:
  - target: SLC19A3 thiamine transporter deficiency
    treatment_effect: BYPASSES
    description: High-dose thiamine increases substrate availability despite reduced SLC19A3 transporter function.
    evidence:
    - reference: PMID:27896110
      reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        This treatment strategy is supported by in vitro studies suggesting that high doses of thiamine and biotin restore insufficient thiamine transport by overexpression of SLC19A3 gene
      explanation: Human clinical case report/review cites in vitro support that high-dose vitamins restore insufficient SLC19A3-mediated thiamine transport.
  - target: Stress-triggered cerebral thiamine-transport failure
    treatment_effect: MODULATES
    description: Early vitamin supplementation supports thiamine availability during stress-triggered episodes.
    evidence:
    - reference: PMID:27905264
      reference_title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        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.
      explanation: Clinical review supports immediate vitamin treatment during suspected encephalopathic episodes.
  target_phenotypes:
  - preferred_term: Encephalopathy
    term:
      id: HP:0001298
      label: Encephalopathy
    temporality: SUBACUTE
  - preferred_term: Confusion
    term:
      id: HP:0001289
      label: Confusion
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  - preferred_term: Dysphagia
    term:
      id: HP:0002015
      label: Dysphagia
  - preferred_term: Dysarthria
    term:
      id: HP:0001260
      label: Dysarthria
  - preferred_term: Dystonia
    term:
      id: HP:0001332
      label: Dystonia
  - preferred_term: Ataxia
    term:
      id: HP:0001251
      label: Ataxia
  - preferred_term: Abnormal basal ganglia morphology
    term:
      id: HP:0002134
      label: Abnormal basal ganglia morphology
  pdb_structures:
  - pdb_id: 8S5U
    description: >-
      Human SLC19A3 in an outward-open, thiamine-bound cryo-EM state, providing
      direct structural context for thiamine recognition by the therapeutic
      target.
    method: cryo-EM
    ligand: thiamine
    target_protein: SLC19A3
    publication: PMID:39358356
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Biotin (5-10 mg/kg/day) and thiamine (up to 40 mg/kg/day with a maximum
      of 1,500 mg daily) are given orally as early in the disease course as
      possible and are continued lifelong.
    explanation: >-
      Current GeneReviews guidance supports early initiation and lifelong oral
      thiamine and biotin treatment.
  - reference: ORPHA:65284
    reference_title: "Biotin-thiamine-responsive basal ganglia disease"
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The disease usually becomes symptomatic in childhood and is life-threatening if left untreated, but symptoms can be reversed and progression prevented by treatment with high doses of biotin and thiamine.
    explanation: Orphanet directly supports high-dose biotin and thiamine as disease-modifying treatment.
  - reference: PMID:35532649
    reference_title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      High doses of biotin and thiamine are the mainstay of the treatment to achieve a favorable outcome.
    explanation: Adult case report and review supports high-dose vitamin treatment.
  - reference: PMID:36657988
    reference_title: "Child Neurology: Infantile Biotin Thiamine Responsive Basal Ganglia Disease: Case Report and Brief Review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      It is considered a treatable condition if vitamin supplementation, most commonly with thiamine and biotin, is initiated early.
    explanation: Child neurology review emphasizes early thiamine/biotin supplementation.
  - reference: PMID:37670342
    reference_title: "Biotin-thiamine responsive basal ganglia disease: a retrospective review of the clinical, radiological and molecular findings of cases in Kuwait with novel variants."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      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.
    explanation: >-
      The 21-person retrospective cohort links prompt management to recovery
      while documenting severe outcomes after delay.
  review_notes: >-
    No randomized component or dose-comparison trial separates the effects of
    thiamine and biotin. Structural and cellular uptake evidence indicates that
    biotin does not bind SLC19A3, but that finding does not exclude a clinical
    contribution through another mechanism.
- name: Acute encephalopathy supportive care
  description: >-
    Acute decompensation may require intensive-care management of seizures and
    raised intracranial pressure, alongside escalation of disease-specific
    thiamine treatment.
  action_category: THERAPEUTIC
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Encephalopathy
    term:
      id: HP:0001298
      label: Encephalopathy
    temporality: SUBACUTE
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Acute encephalopathic episodes may require care in an ICU to manage
      seizures and increased intracranial pressure; thiamine may be increased
      to double the regular dose and given intravenously.
    explanation: >-
      Current GeneReviews guidance describes supportive critical care and
      acute thiamine escalation during encephalopathic episodes.
- name: Avoidance of sodium valproate and ACTH
  description: >-
    Sodium valproate should be avoided for epilepsy treatment in BTBGD, and
    ACTH used for epileptic spasms can induce status dystonicus.
  role: Agents/circumstances to avoid
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_phenotypes:
  - preferred_term: Seizure
    term:
      id: HP:0001250
      label: Seizure
  - preferred_term: Dystonia
    term:
      id: HP:0001332
      label: Dystonia
  evidence:
  - reference: PMID:24260777
    reference_title: "Biotin-Thiamine-Responsive Basal Ganglia Disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Avoid use of sodium valproate to treat epilepsy. Use of ACTH to treat epileptic spasms can induce status dystonicus.
    explanation: GeneReviews explicitly lists sodium valproate and ACTH as agents/circumstances to avoid in BTBGD.
- name: Genetic counseling
  description: >-
    Families benefit from counseling about autosomal recessive recurrence risk
    and targeted SLC19A3 testing for relatives.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:27896110
    reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      early supplementation with biotin and/or thiamine can improve the devastating progression of this condition and allow for appropriate genetic counseling.
    explanation: Case report explicitly links molecular diagnosis and treatment recognition to genetic counseling.
differential_diagnoses:
- name: Leigh syndrome
  disease_term:
    preferred_term: Leigh syndrome
    term:
      id: MONDO:0009723
      label: Leigh syndrome
  description: >-
    BTBGD can mimic Leigh syndrome clinically and radiographically, especially
    with infantile basal ganglia lesions and lactic-acidosis-like presentations.
  evidence:
  - reference: PMID:27896110
    reference_title: "Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      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.
    explanation: Case report directly identifies Leigh syndrome as an important differential diagnosis.
animal_models:
- species: Mus musculus
  genotype: >-
    Homozygous total-body Slc19a3tm1Said knockout, with a
    Slc19a3-null intestine-specific human SLC19A3 transgenic rescue group
    (SLC19A3int) as a comparator
  background: >-
    JAX stock 017343 knockout embryos were crossed with B6D2F1 females to
    generate the transgenic line; wild-type, knockout, and transgenic
    littermates were compared.
  category: Knockout and tissue-specific rescue
  alleles:
  - Slc19a3tm1Said (The Jackson Laboratory stock 017343)
  - >-
    SLC19A3int (study designation for the intestinal epithelial VIL1-promoter
    human SLC19A3 transgene; integration site and registered allele symbol were
    not reported)
  description: >-
    Total-body loss of Slc19a3 lowered circulating and brain thiamine despite
    an 85 mg/kg thiamine diet and altered the brain metabolome. Intestinal
    human SLC19A3 expression produced circulating vitamers equivalent to
    wild-type animals but did not fully normalize brain thiamine. The study
    supports a tissue-specific requirement for transporter function but models
    thiamine distribution and metabolism rather than the complete human
    neurologic syndrome.
  associated_phenotypes:
  - Reduced plasma thiamine
  - Reduced brain thiamine
  - Altered brain metabolome
  evidence:
  - reference: PMID:37623829
    reference_title: The Impacts of Slc19a3 Deletion and Intestinal SLC19A3 Insertion on Thiamine Distribution and Brain Metabolism in the Mouse.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      To evaluate the impact of THTR2 on tissue thiamine status and metabolism,
      we expressed the human SLC19A3 transgene in the intestine of total body
      Slc19a3 knockout (KO) mice.
    explanation: >-
      The abstract directly supports the knockout and intestine-specific human
      transgene comparison; the full methods identify JAX stock 017343 and the
      intestinal epithelial VIL1 promoter but do not report a registered
      integration allele.
  - reference: PMID:37623829
    reference_title: The Impacts of Slc19a3 Deletion and Intestinal SLC19A3 Insertion on Thiamine Distribution and Brain Metabolism in the Mouse.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      KO mice had ~two- and ~three-fold lower plasma and brain thiamine levels
      than WT on the 5× diet.
    explanation: >-
      The knockout directly demonstrates reduced systemic and cerebral thiamine
      despite the high-thiamine diet.
  - reference: PMID:37623829
    reference_title: The Impacts of Slc19a3 Deletion and Intestinal SLC19A3 Insertion on Thiamine Distribution and Brain Metabolism in the Mouse.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      The loss of THTR2 reduced levels of nucleic acid and amino acid
      derivatives in the brain.
    explanation: >-
      Untargeted metabolomics connects transporter loss to altered brain
      metabolism.
experimental_models:
- name: KAIMRCi004-A/B patient-derived BTBGD iPSC neural progenitor model
  description: >-
    Two patient-derived iPSC clones carrying homozygous SLC19A3
    c.1264A>G (p.Thr422Ala) were validated for pluripotency and differentiated
    into neural progenitors. The lines provide a genetically relevant human
    neural resource, but the publication did not yet demonstrate a
    disease-specific transport, metabolic, or injury phenotype.
  experimental_model_type: IPSC_DERIVED_MODEL
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  conditions:
  - Homozygous SLC19A3 c.1264A>G (p.Thr422Ala)
  - Unedited patient-derived iPSC clones differentiated to neural progenitors
  cell_source: >-
    Peripheral-blood-mononuclear-cell-derived iPSC clones from a 10-year-old
    female with BTBGD
  culture_system: >-
    iPSC monolayer culture followed by differentiation to central-nervous-system
    neural progenitors
  publication: PMID:38980565
  evidence:
  - reference: PMID:38980565
    reference_title: "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."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      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).
    explanation: >-
      The report directly identifies the patient source, two clones, and causal
      genotype.
  - reference: PMID:38980565
    reference_title: "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."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      We have confirmed the pluripotency of the generated iPS lines and
      successfully differentiated them to neural progenitors.
    explanation: >-
      The publication directly validates pluripotency and neural-progenitor
      differentiation.
discussions:
- discussion_id: gap_biotin_independent_contribution
  prompt: >-
    Does biotin independently improve BTBGD outcomes when added to high-dose
    thiamine, and if so through what mechanism?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - treatments#High-dose thiamine and biotin supplementation
  - pathophysiology#SLC19A3 thiamine transporter deficiency
  rationale: >-
    Clinical reports generally administer both vitamins without randomized
    component or dose comparisons. Structural and cellular uptake work does not
    detect biotin interaction with SLC19A3, so the historical combination
    regimen should not be interpreted as proof that both components act through
    the transporter.
  evidence:
  - reference: PMID:39358356
    reference_title: Structural basis of thiamine transport and drug recognition by SLC19A3.
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: biotin does not interact with the transporter
    explanation: >-
      This establishes the lack of observed SLC19A3 binding or uptake effect,
      but does not exclude an independent clinical benefit through another
      mechanism.
- discussion_id: gap_selective_brain_vulnerability
  prompt: >-
    Why does a broadly expressed thiamine-transporter defect preferentially
    injure basal ganglia and other cerebral gray matter during physiologic
    stress?
  kind: KNOWLEDGE_GAP
  status: OPEN
  attaches_to:
  - pathophysiology#SLC19A3 thiamine transporter deficiency
  - pathophysiology#Stress-triggered cerebral thiamine-transport failure
  - pathophysiology#Basal ganglia and gray-matter injury
  - animal_models#Mus musculus
  rationale: >-
    Patient-cell studies support impaired stress-induced transporter
    upregulation, and the knockout model shows reduced brain thiamine and
    metabolic changes. Neither establishes why particular gray-matter regions
    are selectively vulnerable or which stress-dependent metabolic bottleneck
    causes the lesion pattern.
  evidence:
  - reference: PMID:24372704
    reference_title: "Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease."
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      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.
    explanation: >-
      Patient fibroblasts demonstrate impaired stress adaptation but do not
      resolve regional brain vulnerability.
  - reference: PMID:37623829
    reference_title: The Impacts of Slc19a3 Deletion and Intestinal SLC19A3 Insertion on Thiamine Distribution and Brain Metabolism in the Mouse.
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: >-
      mutation or inhibition of THTR2 may alter the brain metabolome and reduce
      the thiamine reservoir for TDP biosynthesis.
    explanation: >-
      The mouse study provides a metabolic hypothesis while leaving the
      region-selective human injury mechanism unresolved.
review_notes: >-
  This entry is scoped to biallelic SLC19A3-related thiamine metabolism
  dysfunction syndrome 2; SLC19A2-related Rogers syndrome and TPK1 deficiency
  are distinct disorders. Additional phenotypes surfaced by disease-to-phenotype
  auditing were not bulk-imported because many derive from small, founder, or
  age-specific series; age-related presentations are represented as subtypes
  instead. These presentations do not have distinct MONDO or OMIM identifiers,
  so their subtype_term fields are intentionally omitted. No reusable public
  omics or phenotype dataset accession was verified:
  the mouse metabolomics report stated that deposition would occur without
  providing an accession, and the iPSC characterization data were available on
  request. The datasets section is therefore intentionally omitted. Treatment
  evidence is observational, the independent role of biotin remains unresolved,
  and the stress-triggered mechanism is retained as provisional. The mouse
  study reports JAX stock 017343 for Slc19a3tm1Said but no registered integration
  allele for SLC19A3int. The unedited patient iPSC lines lack an isogenic control
  and a measured transport, metabolic, or injury phenotype, so they are retained
  as a model resource without a modeled_mechanisms link rather than as
  mechanistic validation.
references:
- reference: PMID:24260777
  title: Biotin-Thiamine-Responsive Basal Ganglia Disease.
  tags:
  - GeneReviews
  findings: []
- reference: ORPHA:199348
  title: Thiamine-responsive encephalopathy
  findings: []
- reference: ORPHA:65284
  title: Biotin-thiamine-responsive basal ganglia disease
  findings: []
- reference: PMID:24372704
  title: Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease.
  findings: []
- reference: PMID:27896110
  title: Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease.
  findings: []
- reference: PMID:27905264
  title: "Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment."
  findings: []
- reference: PMID:28677371
  title: Neuropathological characteristics of the brain in two patients with SLC19A3 mutations related to the biotin-thiamine-responsive basal ganglia disease.
  findings: []
- reference: PMID:35532649
  title: "Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia."
  findings: []
- reference: PMID:36657988
  title: "Child Neurology: Infantile Biotin Thiamine Responsive Basal Ganglia Disease: Case Report and Brief Review."
  findings: []
- reference: PMID:37670342
  title: "Biotin-thiamine responsive basal ganglia disease: a retrospective review of the clinical, radiological and molecular findings of cases in Kuwait with novel variants."
  findings: []
- reference: PMID:38980565
  title: "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."
  findings: []
- reference: PMID:39358356
  title: Structural basis of thiamine transport and drug recognition by SLC19A3.
  findings: []
- reference: PMID:37623829
  title: The Impacts of Slc19a3 Deletion and Intestinal SLC19A3 Insertion on Thiamine Distribution and Brain Metabolism in the Mouse.
  findings: []
📚

References & Deep Research

References

13
PMID:24260777
Biotin-Thiamine-Responsive Basal Ganglia Disease.
No top-level findings curated for this source.
ORPHA:199348
Thiamine-responsive encephalopathy
No top-level findings curated for this source.
ORPHA:65284
Biotin-thiamine-responsive basal ganglia disease
No top-level findings curated for this source.
PMID:24372704
Stress-induced upregulation of SLC19A3 is impaired in biotin-thiamine-responsive basal ganglia disease.
No top-level findings curated for this source.
PMID:27896110
Whole exome sequencing reveals compound heterozygous mutations in SLC19A3 causing biotin-thiamine responsive basal ganglia disease.
No top-level findings curated for this source.
PMID:27905264
Biotin-thiamine-responsive basal ganglia disease: catastrophic consequences of delay in diagnosis and treatment.
No top-level findings curated for this source.
PMID:28677371
Neuropathological characteristics of the brain in two patients with SLC19A3 mutations related to the biotin-thiamine-responsive basal ganglia disease.
No top-level findings curated for this source.
PMID:35532649
Biotin-Responsive Basal Ganglia Disease: Treatable Metabolic Disorder with SLC19A3 Mutation Presenting as Rapidly Progressive Dementia.
No top-level findings curated for this source.
PMID:36657988
Child Neurology: Infantile Biotin Thiamine Responsive Basal Ganglia Disease: Case Report and Brief Review.
No top-level findings curated for this source.
PMID:37670342
Biotin-thiamine responsive basal ganglia disease: a retrospective review of the clinical, radiological and molecular findings of cases in Kuwait with novel variants.
No top-level findings curated for this source.
PMID:38980565
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.
No top-level findings curated for this source.
PMID:39358356
Structural basis of thiamine transport and drug recognition by SLC19A3.
No top-level findings curated for this source.
PMID:37623829
The Impacts of Slc19a3 Deletion and Intestinal SLC19A3 Insertion on Thiamine Distribution and Brain Metabolism in the Mouse.
No top-level findings curated for this source.

Deep Research

1
Biotin-Thiamine-Responsive Basal Ganglia Disease Deep Research Fallback ▸

Biotin-Thiamine-Responsive Basal Ganglia Disease Deep Research Fallback

Date: 2026-05-07

Provider Attempts

  • timeout 90s just research-disorder falcon Biotin_Thiamine_Responsive_Basal_Ganglia_Disease terminated by signal 15 before producing an artifact.
  • timeout 90s just research-disorder openai Biotin_Thiamine_Responsive_Basal_Ganglia_Disease terminated by signal 15 before producing an artifact.

Evidence Scope Integrated

The YAML curation was built from generated Orphanet structured records and cached PubMed evidence:

  • ORPHA:65284, the primary biotin-thiamine-responsive basal ganglia disease record, supplies disease scope, synonyms, definition, inheritance, onset, prevalence, SLC19A3 gene assertion, and MONDO:0011841 exact mapping.
  • ORPHA:199348, the thiamine-responsive encephalopathy record, supports the overlapping SLC19A3-related Wernicke-like thiamine-responsive phenotype.
  • PMID:27905264 supports autosomal recessive SLC19A3 disease causation, subacute encephalopathy with dysphagia/dysarthria/seizures, bilateral caudate/putamen MRI abnormalities, and outcome dependence on early treatment.
  • PMID:24372704 supports the cellular mechanism: SLC19A3 encodes thiamine transporter 2, patient tissue shows reduced thiamine transporter function, and patient fibroblasts fail to upregulate SLC19A3 under acidosis/hypoxia.
  • PMID:27896110 supports compound heterozygous SLC19A3 variants, Leigh syndrome differential diagnosis, early thiamine/biotin supplementation, and genetic counseling.
  • PMID:28677371 supports the specific SLC19A3-related CNS lesion pattern and MRI/autopsy-triggered SLC19A3 testing with prompt specific treatment.
  • PMID:35532649 supports adult presentation with seizures, ataxia, dystonia, basal ganglia MRI abnormalities, clinical/MRI improvement after thiamine and biotin, and high-dose vitamin therapy as treatment mainstay.
  • PMID:36657988 supports autosomal recessive inheritance, blood-brain barrier thiamine transport failure, recognized infantile/childhood/adult phenotypes, and early thiamine/biotin supplementation.

No uncached web claims or hand-authored reference-cache content were used.