SLC52A2 and riboflavin transporter deficiency: The recent identification of mutations in the riboflavin transporter genes SLC52A3 (formerly C20orf54) (Green et al., 2010) and SLC52A2 (Johnson et al., 2012) [coding for human riboflavin transporters RFVT3 (formerly RFT2) and RFVT2 (formerly RFT3), respectively] has uncovered the aetiology in a large proportion of cases with Brown-Vialetto-Van Laere syndrome.