They were previously known as Brown–Vialetto–Van Laere syndrome 2 (21BVVLS2; #614707), in which mutations in the SLC52A2 (8q24.3; #607882) or SLC52A3 (20p13; #613350) genes were responsible for the disease occurrence, and as Fazio–Londe disease (FLD; #211500), caused solely by mutations in the SLC52A3 gene [14]. Here, SLC52A3 is linked to progressive bulbar palsy of childhood.