Glycogen storage disease due to phosphoglucomutase deficiency (Orphanet_711) can be described as follows. Glycogen storage disease type XIV (GSDXIV) is a rare metabolic disorder caused by a deficiency in phosphoglucomutase (PGM) enzymatic activity and characterized by recurrent cramps during exercise. Also known as: GSD due to phosphoglucomutase deficiency, GSD type 14, GSDXIV, Glycogen storage disease type 14, Glycogenosis due to phosphoglucomutase deficiency, Glycogenosis type 14, Phosphoglucomutase 1 deficiency.