Mucolipidosis II-related pathogenic variants, p.Gly1049Argfs* and p.Leu1168Glnfs*, inhibit the exit from the endoplasmic reticulum and proteolytic cleavage of GlcNAc-1-phosphotransferase precursor protein (GNPTAB)17. This evidence concerns the gene GNPTAB and mucolipidosis type II.