SLC25A19 and microcephaly: Furthermore, disorders associated with SLC19A3, SLC25A19, and thiamin pyrophosphokinase 1 (TPK1) may result in recurrent encephalopathy, basal ganglia necrosis, generalized dystonia, severe disability, and early mortality [8]; indeed, SLC25A19 pathogenic variants severely reduce mitochondrial TPP, causing Amish lethal microcephaly and thiamine metabolism dysfunction syndrome 4 (Figure 1) [8].