A recent study on pro-inflammatory cytokines in MPSI VA, MPS II and MBD found that, in comparison to normal controls, the levels of IL-6 and TNF-α were significantly elevated in untreated MBD patients (levels were similar to ERT-treated MPS IVA, but lower than untreated MPS IVA patients). This evidence concerns the gene TNF and mucopolysaccharidosis type 4A.