In line with these results, gene set enrichment analysis (GSEA) highlighted that several molecular pathways responsible for cartilage maturation and remodeling such as VEGFR1 (VEGF receptor 1), HOXA5 (homeobox A5), TGFB1 (transforming growth factor β1), and IGF1 (insulin growth factor 1) signaling were significantly downregulated in MPS IH compared with HD pellets (Figure 5, C and D). Here, IGF1 is linked to mucopolysaccharidosis.