ARSA and lysosomal storage disease: Given the preference of UGGT2 for soluble lysosomal proteins, it would be of interest in future studies to examine lysosomes in UGGT2-/- cells or mice as a number of the UGGT2 substrates are associated with lysosomal storage diseases including metachromatic leukodystrophy (arylsulfatase A), Fabry (alpha-galactosidase A), Sandhoff (β-hexosaminidase subunit β), and Schindler (α-N-acetylgalactosaminidase) diseases (Mahuran, 1999; Cesani et al., 2016; Ferreira and Gahl, 2017).