Thiamine metabolism dysfunction syndrome 5 (THMD5) mimicking acute disseminated encephalomyelitis.

Thiamine pyrophosphate (TPP), the substrate of Thiamine pyrophosphate kinase (TPK), is an important cofactor in carbohydrate metabolism, specifically as a cofactor of the Pyruvate dehydrogenase complex (PDH) complex. The nervous system is particularly dependent on TPP due to its reliance on glucose metabolism. In this case, a four-year-old girl had a previously unreported pathogenic variant of the gene encoding TPK (TPK1) which presented as Thiamine metabolism dysfunction syndrome 5 (THMD5; OMIM 614458).