SUMF1 and mucosulfatidosis: Ultra‐rare multiple sulfatase deficiency (MSD; OMIM #272200) is caused by pathogenic variants in SUMF1. 1, 2, 3, 4, 5SUMF1 encodes formylglycine‐generating enzyme (FGE) (EC 1.8.3.7), which is essential for sulfatase activation.6