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Biotin Responsive Basal Ganglia Disease

Summary

  • Rare neurometabolic disorder characterised by recurrent encephalopathy and bilateral basal ganglia lesions
  • Caused by mutations in the SLC19A3 gene, affecting thiamine transport
  • Responsive to biotin and thiamine supplementation, with potential for full recovery if treated early

Pathophysiology

  • Autosomal recessive disorder caused by mutations in the SLC19A3 gene
  • SLC19A3 encodes for thiamine transporter 2 (ThTR2)
  • Impaired thiamine transport leads to:
    • Mitochondrial dysfunction
    • Energy depletion in basal ganglia and other brain regions
    • Increased oxidative stress
  • Biotin may act as a cofactor for carboxylases and enhance residual ThTR2 function

Demographics

  • Rare disorder, with fewer than 100 cases reported worldwide
  • Most commonly affects individuals of Arab descent
  • Typically presents in childhood or adolescence
  • No significant gender predilection

Diagnosis

  • Clinical presentation:
    • Recurrent episodes of encephalopathy
    • Seizures
    • Dystonia
    • Ataxia
    • Cognitive decline
  • Laboratory findings:
    • Normal serum thiamine levels
    • Elevated lactate in cerebrospinal fluid (CSF)
  • Genetic testing:
    • Identification of biallelic mutations in SLC19A3 gene

Imaging

  • MRI findings:
    • Bilateral, symmetrical T2/FLAIR hyperintensities in basal ganglia
    • Caudate nuclei
    • Putamina
    • Thalami
    • Additional involvement may include:
    • Cerebral cortex
    • Brainstem
    • Cerebellum
  • MR spectroscopy:
    • Elevated lactate peak in affected regions
  • Follow-up imaging:
    • Reversibility of lesions with treatment
    • Potential for complete resolution if treated early

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  • 30-year-old patient with biotin related basal ganglia disease during acute presentation 20 years prior.
  • MRI showed old gliotic damage and volume loss of the striatum basal ganglia.

Treatment

  • Biotin supplementation:
    • Typical dose: 5-10 mg/kg/day
  • Thiamine supplementation:
    • Typical dose: 50-100 mg/kg/day
  • Combined biotin and thiamine therapy is more effective than biotin alone
  • Early initiation of treatment is crucial for:
    • Preventing neurological deterioration
    • Reversing existing symptoms
    • Improving long-term outcomes
  • Lifelong supplementation is recommended
  • Supportive care:
    • Anticonvulsants for seizure control
    • Physical and occupational therapy for motor symptoms
  • Genetic counseling for affected families

Differential diagnosis

Differential Diagnosis Distinguishing Feature
Leigh Syndrome Typically earlier onset; lactate elevation in blood and CSF
Pantothenate Kinase-Associated Neurodegeneration "Eye of the tiger" sign on T2-weighted MRI
Glutaric Aciduria Type 1 Characteristic urine organic acid profile; macrocephaly
Carbon Monoxide Poisoning History of exposure; carboxyhaemoglobin levels elevated