A SUMF1 knock‐out mouse model and a SUMF1 knock‐out zebrafish model are not amenable to treatment as they both lack hypomorph FGE variants but are recently described new MSD mouse models with hypomorphic SUMF1 variants (Settembre et al, 2007; Fleming et al, 2022; Sorrentino et al, 2022). Here, SUMF1 is linked to mucosulfatidosis.