Direct functional links between the candidate genes and the etiology of GSD is available for: the lipid transporter ATPase phospholipid transporting 8B1, (ATP8B1) gene [28], the RB transcriptional corepressor 1, (RB1) gene [37], the hepatocyte nuclear factor 1α (HNF1A) gene [38], the bile salt transporter gene sulfotransferase family 2 A member 1, (SULT2A1) gene [10], and the Apolipoprotein L1 and L2 (APOL1 and APOL2) involved in lipid transport. This evidence concerns the gene RB1 and disorder of glycogen metabolism.