However, patients with suspected MPS who have been identified with the specific urinary GAG and oligosaccharide pattern—increased heparan/dermatan sulphates and sialoglycoconjugates (Figs 2B–D and 3B) but normal activities of related lysosomal enzymes—should be considered for diagnosis of MPS plus syndrome and screened for genetic defects in the VPS33A gene. The gene discussed is VPS33A; the disease is mucopolysaccharidosis.