Riboflavin Transporter Deficiency (RTD) is an early onset rare motor neuron (MN) disease caused by variants in SLC52A3 and SLC52A2 genes, encoding the RFVT3 and RFVT2 riboflavin (RF) transporters, respectively [1]. Here, SLC52A2 is linked to hyperinsulinemic hypoglycemia, familial, 4.