SUMF1 and mucosulfatidosis: To evaluate the efficacy of tazarotene and bexarotene on cell types different from fibroblasts, an iPSC line was generated from a MSD patient (compound heterozygous for SUMF1 mutations c.463T > C, p.Ser155Pro and c.1034G > A, p.Arg345His, Appendix Fig S7A–F) Control and MSD patient‐derived iPSC lines were differentiated into neuronal progenitor cells (NPCs) and treated with 5/5 μM tazarotene/bexarotene for 4 days.