CTSA and glycoprotein storage disease: Galactosialidosis (GS) (MIM: 256540) is a glycoprotein storage disease caused by mutations in CTSA, encoding the lysosomal carboxypeptidase protective protein cathepsin A. GS affects different body systems, including the eyes, brain, skeleton, and muscles and develops manifestations, including vision problems, difficulty walking, dark red spots on the skin, spine abnormalities, and intellectual disability, that gets worse with time (Caciotti et al., 2013).