High DPP-IV activity, over 3 MoM was observed in individuals affected with gangliosidosis GM1 and in two patients with Niemann–Pick type B (n = 1) and mucopolysaccharidosis type IIIC (n = 1), see Table 1 and Supplementary Table S2. This evidence concerns the gene DPP4 and mucopolysaccharidosis type 3C.