Introduction: Biotin-Thiamine responsive basal ganglia disease (BTBGD) is a rare, autosomal recessive neurometabolic disorder, characterized by subacute encephalopathy following a febrile illness which is completely reversible with treatment. We describe a case of 15 months old female child of Indian-Muslim origin and her phenotypic-genotypic comparison with previously reported cases in literature.

Case report: This child, born of third degree consanguineous marriage, presented with regression of developmental milestones following a trivial viral infection. On examination she was irritable, had lost walking and sitting with hypotonia and ataxia. MRI brain showed bilateral symmetrical T2 hyperintensities with diffusion restriction in basal ganglia. She was treated with pulse methylprednisolone and high dose multivitamins keeping acute disseminated encephalomyelitis and metabolic encephalopathy as differential diagnosis. At her 3 months follow up she had completely recovered clinically with total resolution on neuroimaging. One year follow up on Biotin and Thiamine showed no further regression despite of infection. Genetic testing revealed a homozygous mutation in exon 2 in SLC19A3 gene which was similar to the only genetically confirmed Indian case, in contrast to exon 5, the founder mutation in the Middle East.

Conclusion:

• Exon 2 appears to be the Indian founder mutation for BTBGD.
• Phenotypic presentations with respect to age of onset, clinical features and neuroimaging seem to be similar in both Exon 2 and Exon 5 variants.
• Biotin and thiamine are essential supplements in children with metabolic encephalopathy awaiting genetic results.