MPS IIIA is caused by mutations in the SGSH gene that result in deficiency of the N-sulfoglucosamine sulfohydrolase enzyme (sulfamidase, EC 3.10.1.1) and subsequent accumulation of undegraded heparan sulphate, lysosomal enlargement and cellular and organ dysfunction [4], [5], [6], [7]. This evidence concerns the gene SGSH and mucopolysaccharidosis type 3A.