Structures and biosynthetic pathways of glycosphingolipids (GSLs). Cer, ceramide; CST, cerebroside sulfotransferase (Gal3st1, sulfatide synthase); GalNAc-T, N-acetylgalactosaminyltransferase I (B4galnt1, GA2/GM2/GD2/GT2 - synthase); G a l T- I, galactosyltransferase I (B4galt6, lactosylceramide synthase); GalT-II, galactosyltransferase II (B3galt4, GA1/GM1/GD1b/GT1c-synthase); GalT-III, galactosyltransferase III (Ugt8a, galactosylceramide synthase); GlcT, glucosyltransferase (Ugcg, glucosylceramide synthase); ST-I, sialyltransferase I (St 3 gal5, GM3-synthase); ST-II, sialyltransferase II (St8Sia1, GD3-synthase); ST-III, sialyltransferase III (St8Sia3, GT3-synthase); ST-IV, sialyltransferase IV (St 3 gal2, GM1b/GD1a/GT1b/GQ1c-synthase); ST-V, sialyltransferase V (St8sia5, GD1c/GT1a/GQ1b/GP1c-synthase); ST-VII, sialyltransferase VII (St6galnac6, GD1aα/GT1aα/GQ1bα/GP1cα-synthase). Official symbols of genes are represented in italics in this figure legend