SLC52A2 and riboflavin transporter deficiency: Here we characterize clinically, genetically and neurophysiologically 18 patients with Brown-Vialetto-Van Laere syndrome caused by mutations in the SLC52A2 gene and report in detail the significant and sustained clinical and biochemical improvements observed in response to high-dose oral riboflavin therapy in two patients and preliminary clinical response data in 13 patients with associated biochemical response data in 10 patients.