PGM1 and congenital disorder of glycosylation: Next, we used the developed technology to study perturbances in nucleotide sugar biosynthesis in phosphoglucomutase 1 (PGM1) deficiency (MIM#614921), a congenital disorder of glycosylation (CDG) affecting the synthesis of the nucleotide sugars UDP-Glc and UDP-Gal (Figure 4a).