THBS1 and mucopolysaccharidosis: Moreover, when MPS II fibroblasts were treated with an enzyme used in enzyme replacement therapy for this MPS type, human recombinant iduronate-2-sulfatase (Elaprase), to normalize GAG levels in cells, the effects of changes in levels of THBS1 and OXTR transcripts were reversed (Figure 8) which again supported the above conclusion.