SLC19A2 and thiamine-responsive megaloblastic anemia syndrome: Thiamine metabolism dysfunction syndrome 1 was caused by SLC19A2 mutations (coding for thiamine transporter-1 dysfunction), thiamine metabolism dysfunction syndrome 2 was caused by SLC19A3 mutations (coding for thiamine transporter-1 dysfunction), thiamine metabolism dysfunction syndrome 3 and thiamine metabolism dysfunction syndrome 4 was caused by SLC25A19 mutations (coding for mitochondrial thiamine pyrophosphate carrier carrier) [1].