Biotinidase Deficiency in the Second Decade with Atypical Neuroimaging Findings.

Biotinidase deficiency is a rare autosomal recessive neurometabolic disorder resulting in biotin deficiency. Our patient presented with seizures and developmental delay since infancy and was started on megavitamin supplements. At 14 years, she presented with motor regression with encephalopathy after discontinuation of vitamins. There were no skin and hair changes. Magnetic resonance imaging (MRI) of the brain showed bilateral symmetrical posterior putamen signal changes. Tandem mass spectroscopy showed increased methyl malonyl carnitine and 3-OH isovaleryl carnitine. There was a low biotinidase level, and a pathogenic variant in the BTD gene in the next-generation sequencing was identified. Special importance is placed on the unusual symmetric posterior putamen involvement seen in MRI of the brain.

Rare Treatable Cause of Demyelinating Leukoencephalopathy That One Cannot Afford to Miss.

Biotinidase deficiency is a treatable neurometabolic disorder. It usually presents during the first year of life with seizures, ataxia, hypotonia, vision and hearing disturbance, alopecia, and skin rashes. It can have various neuroimaging findings but demyelinating leukoencephalopathy is an unusual finding in children with biotinidase deficiency that can cause diagnostic challenge as it can radiologically mimic perinatal hypoxic-ischemic encephalopathy or other leukodystrophies. It reverses with early diagnosis and treatment with biotin supplementation and the outcome is rewarding.

Treatable Neurodegenerative Disorder: Cerebral Folate Transport Deficiency--Two Children from Southern India.

Cerebral folate transport deficiency results from impaired folate transport across the blood:choroid plexus:cerebrospinal fluid (CSF) barrier. This leads to low CSF 5-methyltetrahydrofolate (5MTHF), the active folate metabolite. We are reporting two children with this treatable cerebral folate transport deficiency. Case 1: Seventeen-year-old boy presented with delayed milestones followed by regression, seizures, and intention tremors. On examination child had pyramidal and cerebellar signs. Magnetic resonance imaging (MRI) of brain revealed diffuse cerebral and cerebellar atrophy. Targeted next generation sequencing revealed homozygous missense pathogenic variant in FOLR1 gene in exon 4 c.382C>T p.R128W, confirming the diagnosis of cerebral folate deficiency. Case 2: Six-year-old male child presented with delayed milestones, myoclonic jerks and cognitive regression from 3 years of age. Child had microcephaly with ataxia. Computed tomography (CT) of brain revealed multifocal calcifications. MRI brain revealed cerebellar atrophy with hyperintense T2 signal changes in the subcortical white matter of frontal and temporal lobes. Genetic testing revealed homozygous variant (c.493+2_493+6delTGAGG) in intron 4 of the FOLR1 gene which is a novel pathogenic variant. Both children started on folinic acid and there was a significant improvement in development, behavior, ataxia, and decrease in seizure frequency. In conclusion, cerebral folate transport deficiency should be suspected in every child with global developmental delay, epilepsy, ataxia and neuroimaging showing cerebellar atrophy and calcification. Response to folinic acid supplementation is partial if diagnosed late and treatment initiation is delayed.

Bilateral Striatal Necrosis with Polyneuropathy with a Novel SLC25A19 (Mitochondrial Thiamine Pyrophosphate Carrier OMIMI*606521) Mutation: Treatable Thiamine Metabolic Disorder-A Report of Two Indian Cases.

BACKGROUND: SLC25A19 gene mutations cause Amish congenital lethal microcephaly and bilateral striatal necrosis with polyneuropathy. We are reporting two cases of bilateral striatal necrosis with polyneuropathy due to SLC25A19 gene mutations. METHODS: A 36-month-old boy and a 5-year-old girl, unrelated, presented with recurrent episodes of flaccid paralysis and encephalopathy following nonspecific febrile illness. Examination showed dystonia and absent deep tendon reflexes. RESULTS: Nerve conduction studies showed an axonal polyneuropathy. Magnetic resonance imaging (MRI) of the brain in both cases showed signal changes in the basal ganglia. Next-generation sequencing revealed a novel homozygous missense variation c.910G>A (p.Glu304Lys) in the SLC25A19 gene in the boy and a homozygous mutation c.869T > A (p. Leu290Gln) in the SLC25A19 gene in the girl. Mutations were validated by Sanger sequencing, and carrier statuses of parents of both children were confirmed. Both children improved with thiamine supplementation. CONCLUSION: If any child presents with recurrent encephalopathy with flaccid paralysis, dystonia, and neuropathy, a diagnosis of bilateral striatal necrosis with polyneuropathy due to SLC25A19 mutations should be considered and thiamine should be initiated.