Using the mucopolysaccharidosis type IIIA (MPS-IIIA) murine model, a neurological MPS caused by the N-sulfoglucosamine sulfohydrolase deficiency (Table 1), studies on a chimeric sulphamidase, containing a signal peptide from Apolipoprotein B (ApoB-BD), showed a highly secreted iduronate-2-sulphatase (IDS) and efficient BBB transcytosis and restoration of sulphamidase activity in the brain of treated mice (Sorrentino et al., 2013). This evidence concerns the gene SGSH and mucopolysaccharidosis type 3A.