While deficiency of glucose 6 phosphate transporter protein (
G6PT) which provides transportation of glucose 6 phosphate (G6P) from the cytoplasm to the lumen of the endoplasmic reticulum leads to glucogen storage disease type 1b (GSD 1b), deficiency of G6Pase which provides hydrolysis of G6P to glucose and phosphate leads to glucogen storage disease type 1a (GSD 1a) (1,2).