Alternative titles; symbols
HGNC Approved Gene Symbol: GBE1
Cytogenetic location: 3p12.2 Genomic coordinates (GRCh38) : 3:81,489,703-81,761,645 (from NCBI)
| Location | Phenotype |
Phenotype MIM number |
Inheritance |
Phenotype mapping key |
|---|---|---|---|---|
| 3p12.2 | Glycogen storage disease IV | 232500 | Autosomal recessive | 3 |
| Polyglucosan body disease, adult form | 263570 | Autosomal recessive | 3 |
The GBE1 gene encodes the glycogen branching enzyme (EC 2.4.1.18), which is involved in glycogen synthesis that catalyzes the transfer of alpha-1,4-linked glucosyl units from the outer end of a glycogen chain to an alpha-1,6 position on the same or a neighboring glycogen chain. Branching of the chains is essential to pack a very large number of glycosyl units into a relatively soluble spherical molecule.
Thon et al. (1993) used functional complementation of the Saccharomyces cerevisiae glycogen branching enzyme deficiency to isolate human cDNAs that encode the glycogen branching enzyme. The human and yeast glycogen branching enzymes were found to have 67% identical amino acid sequence over a major portion of their length. The full length of the cDNA was approximately 3 kb. The coding sequence contained 2,106 bp encoding a 702-amino acid protein. The calculated molecular mass of the GBE1 protein, derived from its cDNA sequence, was 80,438 Da.
By Southern blot analysis of DNA derived from human/rodent somatic cell hybrids, Thon et al. (1993) mapped the GBE1 gene to chromosome 3.
Glycogen Storage Disease IV
In 2 patients with the classic hepatic presentation of glycogen storage disease IV (GSD4; 232500), Bao et al. (1996) found 2 missense mutations (607839.0004, 607839.0005) and 1 nonsense mutation (607839.0006) in the GBE1 gene. Transient expression experiments showed that these mutations inactivated glycogen branching enzyme activity. In a different patient with the nonprogressive hepatic form of GSD IV, Bao et al. (1996) identified compound heterozygosity for 2 mutations in the GBE1 gene; one of these resulted in complete loss of GBE1 activity (607839.0003), whereas the other resulted in loss of approximately 50% of GBE1 activity (607839.0002). In a patient with the fatal neonatal neuromuscular form of GSD IV, they found a 210-bp deletion in the GBE1 cDNA (607839.0001). The findings indicated that all 3 forms of GSD IV are caused by mutations in the same gene, and that significant retention of GBE1 activity may underlie milder forms of the disease.
Burrow et al. (2006) reported a 30-month-old girl with GSD IV who had stable congenital hypotonia, gross motor delay, and severe fibrofatty replacement of the musculature, but no hepatic or cardiac involvement. Molecular analysis identified compound heterozygosity for 2 missense mutations in the GBE1 gene (607839.0015 and 607839.0016).
Adult Polyglucosan Body Neuropathy
In 7 Jewish patients with adult polyglucosan body neuropathy (APBN; 263570), Lossos et al. (1998) identified homozygosity for a missense mutation in the GBE1 gene (Y329S; 607839.0002). Related family members who were heterozygous for the mutation had only a partial biochemical defect, thereby demonstrating dosage effect of the mutant allele consistent with simple autosomal recessive transmission. The authors noted that the same mutation had been identified in heterozygous state in a 20-year-old person with normal liver function, and in compound heterozygous state in a nonprogressive form of GSD IV. They concluded that APBN represents an allelic variant of GSD IV.
In a non-Ashkenazi patient with APBN, Ziemssen et al. (2000) identified compound heterozygous mutations in the GBE1 gene: an R515H mutation (607839.0019) and an R524Q mutation (607839.0007); the latter mutation had previously been identified in a patient with GSD IV by Bruno et al. (1999). The findings confirmed that APBN and GSD IV are allelic disorders.
Reviews
In a review and consensus paper focused on GSD IV and APBD, Koch et al. (2023) noted that a variety of GBE1 variants and large gene deletions had been shown to cause reduced GBE enzyme activity, with 128 pathogenic or likely pathogenic variants identified. Exon 12 appeared to be a mutation hotspot. GBE1 sequencing detected about 74% of the pathogenic and likely pathogenic mutations; when combined with deletion duplication analysis, this detection rate increased to about 85%.
Fyfe et al. (1997) showed that a fatal form of GSD IV in Norwegian Forest cats, in which striated muscles and the nervous system are primarily affected, is caused by a 6.1-kb deletion that eliminates exon 12 of the feline GBE1 gene. Ward et al. (2004) showed that a fatal neonatal disorder closely resembling GSD IV in the American Quarter horse is caused by a 102C-A transversion in exon 1 of the GBE1 gene, resulting in a tyr34-to-ter (Y34X) substitution.
Fyfe et al. (2007) further characterized the GBE1 mutation in Norwegian forest cats and found that affected cats are homozygous for a complex rearrangement of genomic DNA in GBE1, constituted by a 334-bp insertion at the site of 6.2-kb deletion that extends from intron 11 to intron 12 (IVS11+1552_IVS12-1339 del6.2kb ins334bp), removing exon 12. Screening of 402 privately owned Norwegian forest cats revealed 58 carriers and 4 affected cats. Not all of these died in the neonatal period, suggesting a viable animal model for the studies of pathophysiology and development of novel therapeutic agents.
Akman et al. (2015) found that transgenic mice homozygous for the GBE1 Y329S hypomorphic allele (607839.0002) developed muscle weakness, late-onset spastic paraplegia affecting the hindlimbs, and premature death. Pathologic examination showed progressive glycogen and polyglucosan body accumulation in various organs. The phenotype was reminiscent of APBD in humans.
In a patient with neonatal hypotonia and cardiomyopathy secondary to glycogen storage disease IV (GSD4; 232500) reported by Tang et al. (1994), Bao et al. (1996) found a 210-bp deletion from nucleotide 873 to 1082 of the GBE1 cDNA. This deletion resulted in a loss of 70 amino acids from the GBE polypeptide (262-331). This deletion, representing the loss of an exon, was caused by an AG-to-AA mutation at a 3-prime acceptor splice site, and abolished GBE1 activity.
Glycogen Storage Disease IV
In a Jewish female infant with the nonprogressive hepatic form of glycogen storage disease IV (GSD4; 232500), Bao et al. (1996) found 2 missense mutations on separate alleles of the GBE1 gene: leu224-to-pro (L224P; 607839.0003) and tyr329-to-ser (Y329S). The L224P mutation resulted in complete loss of GBE1 activity, whereas the Y329S mutation resulted in loss of approximately 50% of GBE1 activity. Bao et al. (1996) detected the Y329S allele in another patient with the nonprogressive form of GSD IV but not in 35 unrelated controls or in patients with the more severe forms of GSD IV. The Y329S substitution resulted from an A-to-C transversion at nucleotide 1076. The second patient with the Y329S allele was 20 years old at the time of report and had normal liver function.
Adult Polyglucosan Body Neuropathy
In 7 Jewish patients with adult polyglucosan body neuropathy (APBN; 263570), Lossos et al. (1998) identified homozygosity for the Y329S mutation. The authors concluded that despite the very different phenotypes of APBN and GSD IV, they are allelic disorders.
Mochel et al. (2012) identified the Y329S mutation in 35 (76%) of 50 patients with APBN, all of whom were of Ashkenazi Jewish origin. Thirteen of the patients carried the Y329S mutation in heterozygous state, but the gene was not exhaustively studied for other possible variants. Akman et al. (2015) performed follow-up of some of the heterozygous patients reported by Mochel et al. (2012). In a cohort of 16 patients of Ashkenazi Jewish descent who were initially found to be heterozygous for the Y329S mutation, Akman et al. (2015) found that 3 were compound heterozygous for Y329S, caused by a c.986A-C transversion in exon 7, and a c.671T-C transition, resulting in a leu224-to-pro (L224P; 607839.0003) substitution. The remaining 16 heterozygous patients carried a complex deep intronic del/ins mutation in intron 15 (607839.0020) that resulted in a truncated protein. Haplotype analysis suggested a founder effect for the deep intronic mutation. The mean GBE activity in compound heterozygotes was 8% of normal compared to 18% of normal in Y329S homozygotes.
Glycogen Storage Disease IV
For discussion of the leu224-to-pro (L224P) mutation in the GBE1 gene that was found in compound heterozygous state in an infant with the nonprogressive hepatic form of glycogen storage disease IV (GSD4; 232500) by Bao et al. (1996), see 607839.0002.
Adult Polyglucosan Body Neuropathy
In 3 patients of Ashkenazi Jewish descent with adult polyglucosan body neuropathy (APBN; 263570), Akman et al. (2015) identified compound heterozygous mutations in the GBE1 gene: a c.671T-C transition, resulting in a leu224-to-pro (L224P) substitution, and the common Y329S mutation (607839.0002).
In an infant with glycogen storage disease IV (GSD4; 232500) who presented with progressive liver cirrhosis and failure and died of liver failure before 4 years of age, Bao et al. (1996) identified a 1633C-T transition in the GBE1 gene, resulting in an arg515-to-cys substitution (R515C).
In a patient with glycogen storage disease IV (GSD4; 232500) who presented in early infancy with progressive liver cirrhosis and failure and subsequently underwent liver transplantation, Bao et al. (1996) identified an 861T-A transversion in the GBE1 gene, resulting in a phe257-to-leu substitution (F257L). The other allele contained a C-to-T transition at nucleotide 1660 (607839.0006) that altered arg524 to a stop codon (R524X).
For discussion of the 1660C-T transition in the GBE1 gene, resulting in an arg524-to-ter (R524X), that was found in compound heterozygous state in a patient with classic hepatic glycogen storage disease IV (GSD4; 232500) by Bao et al. (1996), see 607839.0005.
In a patient with childhood neuromuscular glycogen storage disease IV, Bruno et al. (2004) identified compound heterozygosity for the R524X mutation and H628R (607839.0013).
Glycogen Storage Disease IV
In a 16-month-old infant with a combination of hepatic and muscular features of glycogen storage disease IV (GSD4; 232500), Bruno et al. (1999) identified compound heterozygosity for a G-to-A transition in the GBE1 gene, resulting in an arg524-to-gln (R524Q) substitution, while the other allele was not expressed. The patient was the only child of healthy, unrelated parents. At birth he presented with severe hypotonia, flexion contractures of hips, knees, ankles, elbows, and wrists, and neck pterygium. At age 5 months, he was admitted to hospital for surgical correction of arthrogryposis. At that time, muscle hypotonia, stunted growth, hepatosplenomegaly, and liver dysfunction were noted. Laboratory investigations showed increased levels of liver enzymes, while serum creatine kinase remained normal. Electromyography showed a myopathic pattern, with pseudomyotonic discharges. The status of the patient at 22 months of age suggested that the liver dysfunction and the myopathy were static, that respiratory function was not affected, and that there was no abnormality of the heart or of mental development. In a follow-up study of the patient reported by Bruno et al. (1999), Bruno et al. (2004) identified a second GBE1 mutation on the other allele (607839.0014).
Adult Polyglucosan Body Neuropathy
In a non-Ashkenazi patient with adult polyglucosan body neuropathy (APBN; 263570), Ziemssen et al. (2000) identified compound heterozygosity for the arg524-to-gln mutation and an R515H mutation (607839.0019) in the GBE1 gene.
In a patient with the fatal congenital neuromuscular form of glycogen storage disease IV (GSD4; 232500), Tay et al. (2004) identified a homozygous 627-bp deletion in the GBE1 gene, resulting in the deletion of exons 8-12. Residual branching enzyme activity was 0.8% of normal. The parents were related and had a previous intrauterine death associated with decreased fetal movements and polyhydramnios. The patient died at 5.5 weeks of age.
In the patient with fatal perinatal glycogen storage disease IV (GSD4; 232500) reported by Alegria et al. (1999), Bruno et al. (2004) identified a homozygous G-to-A transition at the donor splice site of intron 1 of the GBE1 gene, resulting in a 274-bp insertion, a premature stop codon, and truncation of the last 654 amino acids, or greater than 90% of the protein. Both unaffected parents were heterozygous for the mutation. The patient died at 4 days of age.
In 2 Syrian sibs, born of consanguineous parents, with fatal perinatal glycogen storage disease IV (GSD4; 232500) reported by van Noort et al. (1993), Bruno et al. (2004) identified a homozygous 1634A-G transition in exon 13 of the GBE1 gene, resulting in a his545-to-arg (H545R) substitution. In a structural model based on the E. coli protein, the H545R mutation was predicted to alter the structure of the protein significantly.
In 2 sibs with congenital neuromuscular glycogen storage disease IV (GSD4; 232500), Bruno et al. (2004) identified compound heterozygosity for 2 mutations in the GBE1 gene: a G-to-T transversion in exon 13, resulting in a glu592-to-ter (E592X) substitution and a 253-bp deletion between exon 3 and exon 7 (607839.0012). Residual GBE1 activity in fibroblasts was less than 5%.
For discussion of the 253-bp deletion in the GBE1 gene that was found in compound heterozygous state in 2 sibs with congenital neuromuscular glycogen storage disease IV by Bruno et al. (2004), see 607839.0011.
In a patient with childhood neuromuscular glycogen storage disease IV (GSD4; 232500), Bruno et al. (2004) identified compound heterozygosity for 2 mutations in the GBE1 gene: an A-to-G transition in exon 14, resulting in a his628-to-arg (H628R) substitution and R524X (607839.0006). Residual GBE1 activity in fibroblasts was 15 to 25%.
In an infant with a combination of hepatic and muscular features of glycogen storage disease IV (GSD4; 232500) reported by Bruno et al. (1999), Bruno et al. (2004) identified compound heterozygosity for 2 mutations in the GBE1 gene: a 1-bp insertion at codon 13 in exon 1 and an R524Q substitution (607839.0007). Residual GBE1 activity in fibroblasts was 5 to 10%.
In a 30-month-old girl with stable congenital neuromuscular glycogen storage disease IV (GSD4; 232500), Burrow et al. (2006) identified compound heterozygosity for a 708G-C transversion and a 784C-T transition in the GBE1 gene, resulting in a gln236-to-his (Q236H) and an arg262-to-cys (R262C; 607839.0016) substitution, respectively. Each parent was a carrier of 1 of the mutations. The authors stated that the patient was unique among patients with GSD IV, in that she had a stable myopathy and exhibited no cardiac or hepatic pathology at age 2.5 years.
For discussion of the 784C-T transition in the GBE1 gene, resulting in an arg262-to-cys (R262C) substitution, that was identified in compound heterozygous state in a patient with glycogen storage disease IV (GSD4; 232500) by Burrow et al. (2006), see 607839.0015.
In a female infant with congenital neuromuscular glycogen storage disease IV (GSD4; 232500), Assereto et al. (2007) identified a homozygous G-to-C transversion in intron 5 of the GBE1 gene (IVS5+5G-C), resulting in 2 abnormal mRNA transcripts lacking exon 5 and exons 5 and 6, respectively, that both led to a frameshift and premature termination. The pregnancy was complicated by polyhydramnios and reduced fetal movements, and she was born with severe hypotonia and flexion contractures. She died at age 4 weeks of cardiorespiratory failure. Each parent was heterozygous for the mutation. Assereto et al. (2007) emphasized that null mutations in the GBE1 gene are associated with a severe, often lethal, phenotype.
In a female infant with congenital neuromuscular glycogen storage disease IV (GSD4; 232500), Assereto et al. (2007) identified a homozygous 1643G-A transition in exon 13 of the GBE1 gene, resulting in a trp548-to-ter (W548X) substitution. The pregnancy was complicated by polyhydramnios and reduced fetal movements. She was born with severe hypotonia and died at age 12 weeks of cardiorespiratory failure. Each parent was heterozygous for the mutation. Assereto et al. (2007) emphasized that null mutations in the GBE1 gene are associated with a severe, often lethal, phenotype.
In a non-Ashkenazi patient with adult polyglucosan body neuropathy (APBN; 263570), Ziemssen et al. (2000) identified compound heterozygosity for an arg524-to-gln mutation (607839.0007) and an arg515-to-his (R515H) substitution in the GBE1 gene. The patient presented at age 46 years with gait disturbance, urinary urge incontinence, and hearing loss. She also had spastic tetraparesis, extensor plantar responses, and impaired sensation in the legs. Sural nerve biopsy showed polyglucosan bodies, and leukocyte GBE1 activity was 20% of normal. Each of her 2 clinically unaffected daughters carried one of the mutations and showed intermediate levels of GBE1 activity (80% of normal).
In 13 patients of Ashkenazi Jewish descent with adult polyglucosan body neuropathy (APBN; 263570), Akman et al. (2015) identified compound heterozygous mutations in the GBE1 gene: in addition to the common founder Y329S mutation (607839.0002), all patients carried a complex deep intronic ins/del mutation in intron 15 (IVS15, +5289_5297del9ins20), resulting in an unstable truncated protein. PCR analysis showed that the abnormal sequence resulted in the splicing of exon 15 into an ectopic splice acceptor site, creating an abnormal exon 16 with a new stop codon. Haplotype analysis was consistent with a founder effect for the deep intronic mutation. The mean GBE activity in compound heterozygotes was 8% of normal compared to 18% of normal in Y329S homozygotes, but there was no obvious difference in phenotype. There were no homozygotes for the deep intronic mutation, suggesting that homozygosity for the mutation may be prenatal lethal. Akman et al. (2015) noted that the mutation was missed by whole-genome sequencing, emphasizing potential pitfalls in genetic diagnostics using this method.
Akman, H. O., Emmanuele, V., Kurt, Y. G., Kurt, B., Sheiko, T., DiMauro, S., Craigen, W. J. A novel mouse model that recapitulates adult-onset glycogenosis type 4. Hum. Molec. Genet. 24: 6801-6810, 2015. [PubMed: 26385640] [Full Text: https://doi.org/10.1093/hmg/ddv385]
Akman, H. O., Kakhlon, O., Coku, J., Peverelli, L., Rosenmann, H., Rozenstein-Tsalkovich, L., Turnbull, J., Meiner, V., Chama, L., Lerer, I., Shpitzen, S., Leitersdorf, E., Paradas, C., Wallace, M., Schiffmann, R., DiMauro, S., Lossos, A., Minassian, B. A. Deep intronic GBE1 mutation in manifesting heterozygous patients with adult polyglucosan body disease. JAMA Neurol. 72: 441-445, 2015. Note: Erratum: JAMA Neurol. 72: 481 only, 2015. [PubMed: 25665141] [Full Text: https://doi.org/10.1001/jamaneurol.2014.4496]
Alegria, A., Martins, E., Dias, M., Cunha, A., Cardoso, M. L., Maire, I. Glycogen storage disease type IV presenting as hydrops fetalis. J. Inherit. Metab. Dis. 22: 330-332, 1999. [PubMed: 10384399] [Full Text: https://doi.org/10.1023/a:1005568507267]
Assereto, S., van Diggelen, O. P., Diogo, L., Morava, E., Cassandrini, D., Carreira, I., de Boode, W.-P., Dilling, J., Garcia, P., Henriques, M., Rebelo, O., ter Laak, H., Minetti, C., Bruno, C. Null mutations and lethal congenital forms of glycogen storage disease type IV. Biochem. Biophys. Res. Commun. 361: 445-450, 2007. [PubMed: 17662246] [Full Text: https://doi.org/10.1016/j.bbrc.2007.07.074]
Bao, Y., Kishnani, P., Wu, J.-Y., Chen, Y.-T. Hepatic and neuromuscular forms of glycogen storage disease type IV caused by mutations in the same glycogen-branching enzyme gene. J. Clin. Invest. 97: 941-948, 1996. [PubMed: 8613547] [Full Text: https://doi.org/10.1172/JCI118517]
Bruno, C., DiRocco, M., Lamba, L. D., Bado, M., Marino, C., Tsujino, S., Shanske, S., Stella, G., Minetti, C., van Diggelen, O. P., DiMauro, S. A novel missense mutation in the glycogen branching enzyme gene in a child with myopathy and hepatopathy. Neuromusc. Disord. 9: 403-407, 1999. [PubMed: 10545044] [Full Text: https://doi.org/10.1016/s0960-8966(99)00040-1]
Bruno, C., van Diggelen, O. P., Cassandrini, D., Gimpelev, M., Giuffre, B., Donati, M. A., Introvini, P., Alegria, A., Assereto, S., Morandi, L., Mora, M., Tonoli, E., Mascelli, S., Traverso, M., Pasquini, E., Bado, M., Vilarinho, L., van Noort, G., Mosca, F., DiMauro, S., Zara, F., Minetti, C. Clinical and genetic heterogeneity of branching enzyme deficiency (glycogenosis type IV). Neurology 63: 1053-1058, 2004. [PubMed: 15452297] [Full Text: https://doi.org/10.1212/01.wnl.0000138429.11433.0d]
Burrow, T. A., Hopkin, R. J., Bove, K. E., Miles, L., Wong, B. L., Choudhary, A., Bali, D., Li, S. C., Chen, Y.-T. Non-lethal congenital hypotonia due to glycogen storage disease type IV. Am. J. Med. Genet. 140A: 878-882, 2006. [PubMed: 16528737] [Full Text: https://doi.org/10.1002/ajmg.a.31166]
Fyfe, J. C., Kurzhals, R. L., Hawkins, M. G., Wang, P., Yuhki, N., Giger, U., Van Winkle, T. J., Haskins, M. E., Patterson, D. F., Henthorn, P. S. A complex rearrangement in GBE1 causes both perinatal hypoglycemic collapse and late-juvenile-onset neuromuscular degeneration in glycogen storage disease type IV of Norwegian forest cats. Molec. Genet. Metab. 90: 383-392, 2007. Note: Erratum: Molec. Genet. Metab. 104: 423 only, 2011. [PubMed: 17257876] [Full Text: https://doi.org/10.1016/j.ymgme.2006.12.003]
Fyfe, J. C., Kurzhals, R. L., Henthorn, P. S., Patterson, D. F. Feline glycogenosis type IV is caused by a complex rearrangement deleting 6 kb of the branching enzyme gene and eliminating an exon. (Abstract) Am. J. Hum. Genet. 61: A251 only, 1997.
Koch, R. L., Soler-Alfonso, C., Kiely, B. T., Asai, A., Smith, A. L., Bali, D. S., Kang, P. B., Landstrom, A. P., Akman, H. O., Burrow, T. A., Orthmann-Murphy, J. L., Goldman, D. S., Pendyal, S., El-Gharbawy, A. H., Austin, S. L., Case, L. E., Schiffmann, R., Hirano, M., Kishnani, P. S. Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: a clinical practice resource. Molec. Genet. Metab. 138: 107525, 2023. [PubMed: 36796138] [Full Text: https://doi.org/10.1016/j.ymgme.2023.107525]
Lossos, A., Meiner, Z., Barash, V., Soffer, D., Schlesinger, I., Abramsky, O., Argov, Z., Shpitzen, S., Meiner, V. Adult polyglucosan body disease in Ashkenazi Jewish patients carrying the tyr329ser mutation in the glycogen-branching enzyme gene. Ann. Neurol. 44: 867-872, 1998. [PubMed: 9851430] [Full Text: https://doi.org/10.1002/ana.410440604]
Mochel, F., Schiffmann, R., Steenweg, M. E., Akman, H. O., Wallace, M., Sedel, F., Laforet, P., Levy, R., Powers, J. M., Demeret, S., Maisonobe, T., Froissart, R., and 12 others. Adult polyglucosan body disease: natural history and key magnetic resonance imaging findings. Ann. Neurol. 72: 433-441, 2012. [PubMed: 23034915] [Full Text: https://doi.org/10.1002/ana.23598]
Tang, T. T., Segura, A. D., Chen, Y.-T., Ricci, L. M., Franciosi, R. A., Splaingard, M. L., Lubinsky, M. S. Neonatal hypotonia and cardiomyopathy secondary to type IV glycogenosis. Acta Neuropath. 87: 531-536, 1994. [PubMed: 8059607] [Full Text: https://doi.org/10.1007/BF00294181]
Tay, S. K. H., Akman, H. O., Chung, W. K., Pike, M. G., Muntoni, F., Hays, A. P., Shanske, S., Valberg, S. J., Mickelson, J. R., Tanji, K., DiMauro, S. Fatal infantile neuromuscular presentation of glycogen storage disease type IV. Neuromusc. Disord. 14: 253-260, 2004. [PubMed: 15019703] [Full Text: https://doi.org/10.1016/j.nmd.2003.12.006]
Thon, V. J., Khalil, M., Cannon, J. F. Isolation of human glycogen branching enzyme cDNAs by screening complementation in yeast. J. Biol. Chem. 268: 7509-7513, 1993. [PubMed: 8463281]
van Noort, G., Straks, W., Van Diggelen, O. P., Hennekam, R. C. M. A congenital variant of glycogenosis type IV. Pediat. Path. 13: 685-698, 1993. [PubMed: 8247964] [Full Text: https://doi.org/10.3109/15513819309048254]
Ward, T. L., Valberg, S. J., Adelson, D. L., Abbey, C. A., Binns, M. M., Mickelson, J. R. Glycogen branching enzyme (GBE1) mutation causing equine glycogen storage disease IV. Mammalian Genome 15: 570-577, 2004. [PubMed: 15366377] [Full Text: https://doi.org/10.1007/s00335-004-2369-1]
Ziemssen, F., Sindern, E., Schroder, J. M., Shin, Y. S., Zange, J., Kilimann, M. W., Malin, J.-P., Vorgerd, M. Novel missense mutations in the glycogen-branching enzyme gene in adult polyglucosan body disease. Ann. Neurol. 47: 536-540, 2000. [PubMed: 10762170]