MME and mucopolysaccharidosis type 3D: Strongly miss-regulated genes also include examples of down-regulated genes, like the MME gene encoding the neprilysin protein and the CAV1 gene encoding caveolin 1 protein which are characteristic for two types of MPS (MPS I, IIID and I, IVB, respectively) and examples of genes characteristic for one type of MPS, the GNS gene encoding glucosamine (N-acetyl)-6-sulfatase (MPS IIID), the APOE gene encoding apoliproteine E (MPS IIIA) and others.