Co-existence of TBCK encephalopathy and medium/short-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (M/SCHAD) in a Puerto Rican girl

We report the case of a Puerto Rican girl who presented with multiple seizure types, epileptic spasms and severe global developmental delay. Her examination was significant for myopathic face, profound hypotonia, and areflexia. Her genetic workup revealed a homozygous pathogenic c.376C>T (p.R126X) mutation in the TBCK gene. A second homozygous likely pathogenic c.908G>T (p.G303V) mutation in the HADH gene, responsible for medium/short-chain 3-hydroxyacyl-CoA dehydrogenase deficiency (M/SCHAD), was also found. Her seizures responded dramatically to IV methylprednisolone infusions, and she has remained stable without metabolic crisis.