Hepatic glycogen storage disease: Deciphering the genotype-phenotype conundrum

Table 1 Summary of various studies showing genetic mutations in patients with hepatic glycogen storage disease

Ref.	Kumar et al[47]	Liang et al[48]	Ahmed et al[49]	Beyzaei et al[50]	Vanduangden et al[51]
Country	India	China	Pakistan	Iran	Thailand
Genetic analysis done	n = 57	n = 49	n = 33	n = 13	n = 8
Genetic subtypes	Ia = 6, Ib = 4, III = 28, VI = 8, Ixa = 2, Ixb = 3, Ixc = 6	Ia = 24, IIIa = 11, Ixa = 8, VI = 3, Ib = 3	Ia = 3, Ib = 7, III = 9, VI = 4, Ixa = 1, Ixb = 2, Ixc = 6, XI = 3	I = 1, III = 4, IV = 1, VI = 2, IX = 3, X = 1, glycogen storage disease II = 1	Ia = 1, III = 3, VI = 3, IX = 1
Variants	n = 49 [G6PC (n = 6), glucose-6-phosphatase transporter/SLC37A4 (n = 4), AGL (n = 28), PYGL (n = 8), PHKA2 (n = 2), PHKB (n = 3), PHKG2 (n = 6)]	n = 45 [G6PC (n = 11), AGL (n = 15), PHKA2 (n = 8), PYGL (n = 6), SLC37A4 (n = 3)]	n = 19 (in 8 genes)	n = 15 [SLC37A4 (n = 2), AGL (n = 4), GBE1 (n = 1), PYGL (n = 2), PHKG2 (n = 1), PHKB (n = 3), PGAM2 (n = 1), PRKAG2 (n = 1)]	n = 11 [G6PC (n = 1), AGL (n = 4), PYGL (n = 5), PHKA2 (n = 1)]
Novel variants	n = 27 [G6PC1 (n = 6), SLC37A4 (n = 5), AGL (n = 24), PYGL (n = 5), PHKA2 (n = 2), PHKB (n = 3) and PHKG2 (n = 4)	n = 22 [G6PC (n = 3), AGL (n = 7), PHKA2 (n = 5), PYGL (n = 6), SLC37A4 (n = 1)]	n = 5 [SLC37A4 (n = 2), AGL (n = 1), PYGL (n = 2)]	n = 10 [AGL (n = 1), SLC37A4 (n = 2), PHKB (n = 3), PGAM2 (n = 1), PYGL (n = 1), PRKAG2 (n = 1), GBE (n = 1)]	n = 2 [AGL (n = 2)]

AGL: amylo-alpha-1,6-glucosidase and 4-alpha-glucanotransferase; GBE: Glycogen branching enzyme; G6PC: Glucose-6-phosphatase-α; PGAM2: Phosphoglycerate mutase 2; PHKA2: Phosphorylase kinase regulatory subunit alpha 2; PHKB: Glycogen phosphorylase kinase beta-subunit; PHKG2: Phosphorylase kinase catalytic subunit gamma 2; PRKAG2: Protein kinase AMP-activated non-catalytic subunit gamma 2; PYGL: Glycogen phosphorylase liver form; SLC37A4: Solute carrier family 37 member 4.