Among them, there is the previously described CLU gene encoding clusterin, which undergoes altered expression in many types of MPS (highly changed levels of expression were observed in MPS II, IIIC, IVB, VI and IX) as well as the CD9 gene (encoding surface glycoprotein that forms complexes with integrins) which undergoes strong overexpression in MPS II, IIIA, IIIB, IIIC, IIID, IVB, VI and IX. Here, CD9 is linked to mucopolysaccharidosis type 2.