Supplementary table 1a.PHKA2 variants predicted to be pathogenic and likely pathogenic, based on the American College of Medical Genetics Criteria, identified in our study cohort (Patients 1-12) and from analysis of a further 24 families.

Location / cDNA change / amino acid change / References
Exon 2 / c.133C>T / p.Arg45Trp / (Davit-Spraul et al 2011; Tsilianidis et al 2013; Wang et al 2013; Brown et al 2015), Patients 1 and 2
Exon 2 / c.134G>A / p.Arg45Gln / Patient 3
Intron 5 / c.537+2T>C / intronic / Patient 4, (c.537+5G>A reported (Davit-Spraul et al 2011; Choi et al 2016)
Exon 6 / c.556C>T / p.Arg186Cys / (Hendrickx et al 1996; Hendrickx et al 1999; Davit-Spraul et al 2011)
Exon 6 / c.557G>A / p.Arg186His / (Burwinkel et al 1996; Hendrickx et al 1998; Hendrickx et al 1999; Roscher et al 2014)
Exon 8 / c.811delG / p.Glu271Lysfs*3 / Patient 5
Exon 9 / c.883C>T / p.Arg295Cys / (Ban et al 2003; Tsilianidis et al 2013), Patients 6 and 7
Exon 9 / c.884G>A / p.Arg295His / (Hendrickx et al 1999; Choi et al 2016), Patient 8
Exon 12 / c.1205G>A / p.Trp402* / This study
Intron 13-20 / c.1324+533_2227-1762del / This study
Intron 16 / c.1715-2A>G / intronic / Patient 9
Exon 21 / c.2337dupT / p.Leu780Serfs*30 / This study
Exon 21 / c.2238_2239delTG insGAACAGGCC / p.Ser746Argfs*11 / Patient 10
Exon 23 / c.2593delT / p.Ser865Leufs*49 / This study
Exon 31 / c.3334G>T / p.Glu1112* / Patient 11
Exon 32 / c.3440dupT / p.Thr1148Aspfs*55 / This study
Exon 33 / c.3614C>T / p.Pro1205Leu / (van den Berg et al 1995; Hirono et al 1998; Achouitar et al 2011; Davit-Spraul et al 2011; Roscher et al 2014; Choi et al 2016), Patient 12

Supplementary table 1b.PHKA2 variants of unknown clinical significance (VOUS), based on the American College of Medical Genetics Criteria, identified in our study cohort (Patients 1-12) and from analysis of a further 24 families.

Location / cDNA change / amino acid change / References
exon 4 / c.301_303delAAG / p.Lys101del / This study
Exon 7 / c.708G>C / p.Glu236Asp / This study
Exon 8 / c.749C>T / p.Ser250Leu / This study
Exon 12 / c.1215C>T / p.Ser405Ser / This study
Exon 15 / c.1493C>T / p.Pro498Leu / (Beauchamp et al 2007)
Exon 16 / c.1576G>A / p.Asp526Asn / This study
Exon 16 / c.1712T>C / p.Leu571Pro / This study
Intron 18 / c.1963+3A>G / This study
Exon 33 / c.3629G>A / p.Gly1210Glu / (Rudolfova et al 2001)

Supplementary table 1c.PHKA2 variants predicted to be likely benign or benign, based on the American College of Medical Genetics Criteria, identified in our study cohort (Patients 1-12) and from analysis of a further 24 families.

Location / cDNA change / amino acid change / rs number / Minor allele frequency (ExAC)
Intron 7 / c.718-3C>T / intronic / rs151344532 / 0.01092
Exon 2 / c.112G>C / p.Glu38Gln / rs17313469 / 0.01985
Exon 18 / c.1952C>A / p.Thr651Asn / rs149991825 / 0.00497
Exon 19 / c.2077A>G / p.Ile693Val / rs143732206 / 0.008308
Intron 21 / c.2361-12A>C / rs148877451 / 0.01041
Exon 22 / c.2436G>A / p.Gly812Gly / rs61733281 / 0.007532

References

Achouitar S, Goldstein JL, Mohamed M, et al (2011) Common mutation in the PHKA2 gene with variable phenotype in patients with liver phosphorylase b kinase deficiency. Mol Genet Metab 104: 691-694.

Ban K, Sugiyama K, Goto K, Mizutani F, Togari H (2003) Detection of PHKA2 gene mutation in four Japanese patients with hepatic phosphorylase kinase deficiency. Tohoku J Exp Med 200: 47-53.

Beauchamp NJ, Dalton A, Ramaswami U, et al (2007) Glycogen storage disease type IX: High variability in clinical phenotype. Mol Genet Metab 92: 88-99.

Brown LM, Corrado MM, van der Ende RM, et al (2015) Evaluation of glycogen storage disease as a cause of ketotic hypoglycemia in children. J Inherit Metab Dis 38: 489-493.

Burwinkel B, Shin YS, Bakker HD, et al (1996) Mutation hotspots in the PHKA2 gene in X-linked liver glycogenosis due to phosphorylase kinase deficiency with atypical activity in blood cells (XLG2). Hum Mol Genet 5: 653-658.

Choi R, Park HD, Kang B, et al (2016) PHKA2 mutation spectrum in Korean patients with glycogen storage disease type IX: prevalence of deletion mutations. BMC Med Genet 17: 33.

Davit-Spraul A, Piraud M, Dobbelaere D, et al (2011) Liver glycogen storage diseases due to phosphorylase system deficiencies: diagnosis thanks to non invasive blood enzymatic and molecular studies. Mol Genet Metab 104: 137-143.

Hendrickx J, Bosshard NU, Willems P, Gitzelmann R (1998) Clinical, biochemical and molecular findings in a patient with X-linked liver glycogenosis followed for 40 years. Eur J Pediatr 157: 919-923.

Hendrickx J, Dams E, Coucke P, Lee P, Fernandes J, Willems PJ (1996) X-linked liver glycogenosis type II (XLG II) is caused by mutations in PHKA2, the gene encoding the liver alpha subunit of phosphorylase kinase. Hum Mol Genet 5: 649-652.

Hendrickx J, Lee P, Keating JP, et al (1999) Complete genomic structure and mutational spectrum of PHKA2 in patients with x-linked liver glycogenosis type I and II. Am J Hum Genet 64: 1541-1549.

Hirono H, Shoji Y, Takahashi T, et al (1998) Mutational analyses in four Japanese families with X-linked liver phosphorylase kinase deficiency type 1. J Inherit Metab Dis 21: 846-852.

Roscher A, Patel J, Hewson S, et al (2014) The natural history of glycogen storage disease types VI and IX: Long-term outcome from the largest metabolic center in Canada. Mol Genet Metab 113: 171-176.

Rudolfova J, Slovackova R, Trbusek M, Peskova K, St'astna S, Kozak L (2001) Identification of three novel mutations in the PHKA2 gene in Czech patients with X-linked liver glycogenosis. J Inherit Metab Dis 24: 85-87.

Tsilianidis LA, Fiske LM, Siegel S, et al (2013) Aggressive therapy improves cirrhosis in glycogen storage disease type IX. Mol Genet Metab.

van den Berg IE, van Beurden EA, Malingre HE, et al (1995) X-linked liver phosphorylase kinase deficiency is associated with mutations in the human liver phosphorylase kinase alpha subunit. Am J Hum Genet 56: 381-387.

Wang J, Cui H, Lee NC, et al (2013) Clinical application of massively parallel sequencing in the molecular diagnosis of glycogen storage diseases of genetically heterogeneous origin. Genet Med 15: 106-114.