SLC52A3 and riboflavin transporter deficiency: Another distinctive feature of patients with SLC52A2 mutations is a lack of upper motor neuron signs in the lower limbs, a commonly reported clinical feature of Brown-Vialetto-Van Laere syndrome (Gallai et al., 1981; Hawkins et al., 1990; Francis et al., 1993; Voudris et al., 2002; De Grandis et al., 2005; Dipti et al., 2005; Koul et al., 2006) and, in particular, reported in patients with mutations in SLC52A3 (Green et al., 2010).