SLC52A2 and riboflavin transporter deficiency: In the last decade, mutations in the human RF transporter genes SLC52A2 (encoding for RFVT2) and SLC52A3 (encoding for RFVT3) were demonstrated as causative factor for a neurodegenerative disorder referred to as riboflavin transporter deficiency (RTD), formerly known as Brown-Vialetto-Van Laere syndrome [27].