TPP1 and mucopolysaccharidosis type 2: To date, FDA‐ or European Medicines Agency (EMA)‐approved ERT therapies are available for GD type 1, Fabry disease (FbD), Pompe disease, mucopolysaccharidosis (MPS) 1 (or Hurler syndrome), MPS 2 (or Hunter syndrome), MPS 4 A (or Morquio syndrome), MPS 6 (or Maroteaux‐Lamy syndrome), MPS 7 (or Sly syndrome), α‐mannosidosis (AM) deficiency, lysosomal acid lipase (LAL) deficiency, and CLN2 [166].