Adult Polyglucosan Body Disease

Mendelian MONDO:0009897 Pathograph 35 Show in embeddings browser glycogen storage disease due to glycogen branching enzyme deficiency hereditary peripheral neuropathy

Adult polyglucosan body disease is an autosomal recessive, adult-onset GBE1-related glycogen storage disease in which deficient glycogen branching enzyme activity causes poorly branched glycogen, polyglucosan body accumulation, progressive neurogenic bladder, spastic gait, peripheral neuropathy, and variable cognitive decline.

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1
Inheritance
5
Pathophys.
1
Histopath.
23
Phenotypes
35
Pathograph
1
Genes
6
Medical Actions
1
Trials
6
References
1
Deep Research
👪

Inheritance

1
Autosomal recessive inheritance HP:0000007
Adult polyglucosan body disease is inherited in an autosomal recessive manner due to biallelic pathogenic variants in GBE1.
Autosomal recessive inheritance
Show evidence (2 references)
ORPHA:206583 SUPPORT Other
"- Autosomal recessive"
Orphanet lists autosomal recessive inheritance for APBD.
PMID:33141444 SUPPORT Other
"Adult polyglucosan body disease (APBD) represents a complex autosomal recessive inherited neurometabolic disorder due to homozygous or compound heterozygous pathogenic variants in GBE1 gene"
This review directly states autosomal recessive inheritance and biallelic GBE1 variants.
⚙

Pathophysiology

5
GBE1 deficiency and impaired glycogen branching
Pathogenic GBE1 variants reduce glycogen branching enzyme activity, impairing glycogen synthesis and producing poorly branched glycogen.
GBE1 hgnc:4180 HUGO Gene Nomenclature Committee (hgnc) Relation: this pathophysiological event involves this gene This pathophysiological event involves GBE1 (hgnc:4180). hgnc:4180 is a gene from the HUGO Gene Nomenclature Committee.
glycogen biosynthetic process GO:0005978 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves decreased glycogen biosynthetic process (GO:0005978). GO:0005978 is a biological process from the Gene Ontology. ↓ DECREASED glycogen metabolic process GO:0005977 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal glycogen metabolic process (GO:0005977). GO:0005977 is a biological process from the Gene Ontology. ⚠ ABNORMAL
1,4-alpha-glucan branching enzyme activity GO:0003844 Gene Ontology (GO) Relation: this pathophysiological event involves this molecular function This pathophysiological event involves decreased 1,4-alpha-glucan branching enzyme activity (GO:0003844). GO:0003844 is a molecular function from the Gene Ontology. ↓ DECREASED
Downstream
Polyglucosan body accumulation Impaired glycogen branching leads to accumulation of poorly branched glycogen known as polyglucosan.
Reduced glycogen branching enzyme activity Pathogenic GBE1 variants reduce or abolish glycogen branching enzyme activity.
Show evidence (2 references)
PMID:36796138 SUPPORT Other
"Glycogen storage disease type IV (GSD IV) is an ultra-rare autosomal recessive disorder caused by pathogenic variants in GBE1 which results in reduced or deficient glycogen branching enzyme activity."
This directly supports GBE1 variants causing reduced glycogen branching enzyme activity.
PMID:25665141 SUPPORT Human Clinical
"We identified a deep intronic mutation in this allele, GBE1-IVS15+5289_5297delGTGTGGTGGinsTGTTTTTTACATGACAGGT, which acts as a gene trap, creating an ectopic last exon."
This supports pathogenic GBE1 variants as molecular causes of APBD.
Polyglucosan body accumulation
Deficient glycogen branching enzyme activity causes storage of abnormal glycogen as polyglucosan bodies in central nervous system, peripheral nerve, autonomic fibers, and skeletal muscle tissues.
glycogen metabolic process GO:0005977 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal glycogen metabolic process (GO:0005977). GO:0005977 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Peripheral nerve, autonomic, and neuromuscular involvement Polyglucosan storage involves peripheral nerve, autonomic fibers, and skeletal muscle, providing a shared branch for bladder, neuropathic, sensory, weakness, and mobility-complication phenotypes, with EMG modeled separately as an observational readout.
White matter and motor tract degeneration Polyglucosan storage involves brain white matter, spinal cord, and brainstem motor pathways, connecting storage pathology to white matter and motor tract degeneration.
Proteostasis and cellular stress dysregulation APBD polyglucosan storage and GBE1 deficiency are associated with secondary cellular stress and proteostasis pathway dysregulation in patient-derived lymphoblasts.
Show evidence (2 references)
PMID:33141444 SUPPORT Other
"deficiency of glycogen-branching enzyme and secondary storage of glycogen in the form of polyglucosan bodies, involving the skeletal muscle, diaphragm, peripheral nerve (including autonomic fibers), brain white matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser extent heart,..."
This directly supports the affected tissues and polyglucosan storage mechanism.
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"Polyglucosan bodies accumulate in the central and peripheral nervous systems and are often associated with glycogen branching enzyme (GBE) deficiency."
This links GBE deficiency to polyglucosan body accumulation in central and peripheral nervous systems.
Peripheral nerve, autonomic, and neuromuscular involvement
APBD storage pathology affects peripheral nerves, autonomic fibers, nerve roots, and skeletal muscle, producing bladder sphincter dysfunction, neuropathy with distal sensory impairment, weakness, and secondary mobility or skin complications. Electromyography is represented separately as an observational readout of this tissue branch.
transmission of nerve impulse GO:0019226 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal transmission of nerve impulse (GO:0019226). GO:0019226 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Downstream
Neurogenic bladder Neurogenic bladder is linked conservatively to the combined peripheral, autonomic, and neuromuscular branch because the cohort does not distinguish autonomic fiber pathology from central bladder-pathway involvement.
Urinary incontinence Neurogenic bladder and autonomic dysfunction lead to urinary incontinence.
Urinary bladder sphincter dysfunction Autonomic and bladder pathway involvement produces bladder sphincter dysfunction.
Orthostatic hypotension Autonomic dysfunction in classic GBE1-APBD can include orthostatic hypotension.
Constipation Autonomic dysfunction in classic GBE1-APBD can include constipation.
Peripheral neuropathy Peripheral neuropathy is linked to this tissue-involvement branch, while the intervening injury process remains unresolved in the cached cohort.
Peripheral axonal neuropathy Peripheral nerve storage pathology produces axonal neuropathy.
Distal sensory impairment Axonal neuropathy with vibration loss produces distal sensory impairment.
Muscle weakness Skeletal muscle and neuromuscular involvement can manifest as weakness.
Limitation of joint mobility Reduced mobility and neuromuscular disease may contribute to joint mobility limitation.
Skin ulcer Skin ulcers are modeled as a secondary complication of neuropathy or reduced mobility.
Show evidence (3 references)
PMID:33141444 SUPPORT Other
"deficiency of glycogen-branching enzyme and secondary storage of glycogen in the form of polyglucosan bodies, involving the skeletal muscle, diaphragm, peripheral nerve (including autonomic fibers), brain white matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser extent heart,..."
Clinical review supports the affected peripheral, autonomic, and neuromuscular tissues.
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"The most common clinical findings were neurogenic bladder (100%), spastic paraplegia with vibration loss (90%), and axonal neuropathy (90%)."
Natural history cohort supports autonomic bladder involvement, vibration loss, and axonal neuropathy.
PMID:20301758 SUPPORT Other
"neurogenic bladder, gait difficulties (i.e., spasticity and weakness) from mixed upper and lower motor neuron involvement, sensory loss predominantly in the distal lower extremities, autonomic dysfunction"
GeneReviews summarizes the same bladder, motor, sensory, and autonomic involvement in classic GBE1-APBD.
White matter and motor tract degeneration
APBD neuroimaging shows white matter abnormalities and medulla/spinal atrophy involving motor tracts, consistent with progressive spastic gait and pyramidal signs.
Downstream
Gait disturbance Motor-tract involvement is linked to the characteristic gait disturbance, although the cached phenotype record does not test this causal route.
Spasticity Central motor-tract involvement is linked to the characteristic spastic motor phenotype.
Spastic paraplegia Motor tract involvement produces spastic paraplegia in APBD.
Abnormal pyramidal sign Pyramidal-tract involvement is linked to upper motor neuron signs, while the APBD-specific causal step is inferred from imaging and phenotype data.
Abnormal cerebral white matter morphology APBD neuroimaging demonstrates cerebral white matter abnormalities.
Dementia Dementia is linked conservatively to central nervous system degeneration; the cached evidence does not isolate a white-matter-mediated route.
Ataxia Cerebellar and brainstem involvement can produce ataxia.
Atypical behavior White matter and cognitive involvement can be accompanied by behavioral changes.
Intellectual disability APBD cognitive involvement is linked conservatively to the Orphanet intellectual disability phenotype.
Hemiparesis Motor tract degeneration can produce paresis phenotypes.
Abnormality of extrapyramidal motor function Orphanet lists extrapyramidal motor involvement, but cached evidence does not resolve the intermediate mechanism.
Show evidence (1 reference)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"Neuroimaging showed hyperintense white matter abnormalities on T2 and fluid attenuated inversion recovery sequences predominantly in the periventricular regions, the posterior limb of the internal capsule, the external capsule, and the pyramidal tracts and medial lemniscus of the pons and medulla."
This directly supports white matter and motor tract involvement in APBD.
Proteostasis and cellular stress dysregulation
Human APBD lymphoblast proteomics implicates secondary dysregulation of protein ubiquitination, unfolded protein and endoplasmic reticulum stress responses, TOR signaling, glycolysis, and cell death pathways.
protein ubiquitination GO:0016567 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal protein ubiquitination (GO:0016567). GO:0016567 is a biological process from the Gene Ontology. ⚠ ABNORMAL response to endoplasmic reticulum stress GO:0034976 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal response to endoplasmic reticulum stress (GO:0034976). GO:0034976 is a biological process from the Gene Ontology. ⚠ ABNORMAL TOR signaling GO:0031929 Gene Ontology (GO) Relation: this pathophysiological event involves this biological process This pathophysiological event involves abnormal TOR signaling (GO:0031929). GO:0031929 is a biological process from the Gene Ontology. ⚠ ABNORMAL
Show evidence (1 reference)
DOI:10.3389/fneur.2023.1261125 SUPPORT In Vitro
"Bioinformatic analyses indicated multiple canonical pathways and protein–protein interaction networks to be statistically markedly enriched in APBD subjects, including: RNA processing/transport/translation, cell cycle control/replication, mTOR signaling, protein ubiquitination, unfolded protein..."
This small lymphoblast discovery study supports APBD-associated cellular stress and proteostasis dysregulation, with tissue and causal-direction limitations.
✶

Histopathology

1
Polyglucosan bodies in nervous system and skeletal muscle
APBD is histologically characterized by structurally abnormal glycogen deposits, or polyglucosan bodies, in multiple nervous system and neuromuscular cell types.
Show evidence (1 reference)
PMID:33141444 SUPPORT Other
"deficiency of glycogen-branching enzyme and secondary storage of glycogen in the form of polyglucosan bodies, involving the skeletal muscle, diaphragm, peripheral nerve (including autonomic fibers), brain white matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser extent heart,..."
This clinical review supports polyglucosan body storage across nervous system and skeletal muscle tissues as the characteristic histopathologic feature.
⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.
Pathograph: causal mechanism network for Adult Polyglucosan Body Disease Interactive directed graph showing how pathophysiology mechanisms, phenotypes, genetic factors and variants, experimental models, environmental triggers, and treatments relate through causal and linked edges.
●

Phenotypes

23
Cardiovascular 1
Orthostatic hypotension HP:0001278 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Orthostatic hypotension (HP:0001278). HP:0001278 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301758 SUPPORT Other
"autonomic dysfunction (associated with orthostatic hypotension and constipation)"
GeneReviews lists orthostatic hypotension as part of APBD autonomic dysfunction.
Digestive 1
Constipation HP:0002019 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Constipation (HP:0002019). HP:0002019 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301758 SUPPORT Other
"autonomic dysfunction (associated with orthostatic hypotension and constipation)"
GeneReviews lists constipation as part of APBD autonomic dysfunction.
Genitourinary 1
Neurogenic bladder VERY_FREQUENT HP:0000011 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Neurogenic bladder (HP:0000011). HP:0000011 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"The most common clinical findings were neurogenic bladder (100%), spastic paraplegia with vibration loss (90%), and axonal neuropathy (90%)."
This directly supports neurogenic bladder as a very frequent APBD phenotype.
ORPHA:206583 SUPPORT Other
"| HP:0000011 | Neurogenic bladder | Very frequent (99-80%) |"
Orphanet lists neurogenic bladder as very frequent.
Integument 1
Skin ulcer FREQUENT HP:0200042 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Skin ulcer (HP:0200042). HP:0200042 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0200042 | Skin ulcer | Frequent (79-30%) |"
Orphanet lists skin ulcer as frequent.
Musculoskeletal 4
Spasticity VERY_FREQUENT HP:0001257 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Spasticity (HP:0001257). HP:0001257 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:206583 SUPPORT Other
"| HP:0001257 | Spasticity | Very frequent (99-80%) |"
Orphanet lists spasticity as very frequent.
PMID:36796138 SUPPORT Other
"The adult-onset form of GSD IV, referred to as adult polyglucosan body disease (APBD), is a neurodegenerative disease characterized by neurogenic bladder, spastic paraparesis, and peripheral neuropathy."
This directly supports spastic paraparesis as a characteristic feature.
Spastic paraplegia VERY_FREQUENT HP:0001258 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Spastic paraplegia (HP:0001258). HP:0001258 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"The most common clinical findings were neurogenic bladder (100%), spastic paraplegia with vibration loss (90%), and axonal neuropathy (90%)."
This directly supports spastic paraplegia as a very frequent APBD phenotype.
Muscle weakness VERY_FREQUENT HP:0001324 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Muscle weakness (HP:0001324). HP:0001324 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0001324 | Muscle weakness | Very frequent (99-80%) |"
Orphanet lists muscle weakness as very frequent.
Limitation of joint mobility OCCASIONAL HP:0001376 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Limitation of joint mobility (HP:0001376). HP:0001376 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0001376 | Limitation of joint mobility | Occasional (29-5%) |"
Orphanet lists limitation of joint mobility as occasional.
Nervous System 8
Gait disturbance VERY_FREQUENT HP:0001288 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Gait disturbance (HP:0001288). HP:0001288 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"The median age was 51 years for the onset of neurogenic bladder symptoms, 63 years for wheelchair dependence, and 70 years for death."
Wheelchair dependence supports progressive gait disability in APBD.
ORPHA:206583 SUPPORT Other
"| HP:0001288 | Gait disturbance | Very frequent (99-80%) |"
Orphanet lists gait disturbance as very frequent.
Peripheral neuropathy VERY_FREQUENT HP:0009830 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Peripheral neuropathy (HP:0009830). HP:0009830 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"The most common clinical findings were neurogenic bladder (100%), spastic paraplegia with vibration loss (90%), and axonal neuropathy (90%)."
This directly supports axonal neuropathy as very frequent.
ORPHA:206583 SUPPORT Other
"| HP:0009830 | Peripheral neuropathy | Very frequent (99-80%) |"
Orphanet lists peripheral neuropathy as very frequent.
Abnormal cerebral white matter morphology HP:0002500 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal cerebral white matter morphology (HP:0002500). HP:0002500 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"Neuroimaging showed hyperintense white matter abnormalities on T2 and fluid attenuated inversion recovery sequences predominantly in the periventricular regions, the posterior limb of the internal capsule, the external capsule, and the pyramidal tracts and medial lemniscus of the pons and medulla."
This directly supports cerebral white matter abnormalities on APBD MRI.
Dementia OCCASIONAL HP:0000726 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Dementia (HP:0000726). HP:0000726 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"As the disease progressed, mild cognitive decline may have affected up to half of the patients."
This supports acquired cognitive involvement in APBD but does not by itself establish dementia; the dementia frequency is supported by Orphanet.
ORPHA:206583 SUPPORT Other
"| HP:0000726 | Dementia | Occasional (29-5%) |"
Orphanet lists dementia as occasional.
Ataxia OCCASIONAL HP:0001251 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Ataxia (HP:0001251). HP:0001251 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0001251 | Ataxia | Occasional (29-5%) |"
Orphanet lists ataxia as occasional.
Atypical behavior FREQUENT HP:0000708 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Atypical behavior (HP:0000708). HP:0000708 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0000708 | Atypical behavior | Frequent (79-30%) |"
Orphanet lists atypical behavior as frequent.
Intellectual disability VERY_FREQUENT HP:0001249 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Intellectual disability (HP:0001249). HP:0001249 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
ORPHA:206583 SUPPORT Other
"| HP:0001249 | Intellectual disability | Very frequent (99-80%) |"
Orphanet lists intellectual disability as very frequent.
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"As the disease progressed, mild cognitive decline may have affected up to half of the patients."
The human cohort supports cognitive involvement but describes acquired cognitive decline rather than developmental intellectual disability.
Hemiparesis VERY_FREQUENT HP:0001269 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Hemiparesis (HP:0001269). HP:0001269 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0001269 | Hemiparesis | Very frequent (99-80%) |"
Orphanet lists hemiparesis as very frequent.
Constitutional 1
Urinary incontinence VERY_FREQUENT HP:0000020 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Urinary incontinence (HP:0000020). HP:0000020 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0000020 | Urinary incontinence | Very frequent (99-80%) |"
Orphanet lists urinary incontinence as very frequent.
Other 6
Peripheral axonal neuropathy VERY_FREQUENT HP:0003477 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Peripheral axonal neuropathy (HP:0003477). HP:0003477 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"The most common clinical findings were neurogenic bladder (100%), spastic paraplegia with vibration loss (90%), and axonal neuropathy (90%)."
This directly supports axonal neuropathy as a very frequent APBD phenotype.
Distal sensory impairment FREQUENT HP:0002936 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Distal sensory impairment (HP:0002936). HP:0002936 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"The most common clinical findings were neurogenic bladder (100%), spastic paraplegia with vibration loss (90%), and axonal neuropathy (90%)."
Vibration loss supports distal sensory impairment in APBD.
ORPHA:206583 SUPPORT Other
"| HP:0002936 | Distal sensory impairment | Frequent (79-30%) |"
Orphanet lists distal sensory impairment as frequent.
Abnormal pyramidal sign VERY_FREQUENT HP:0007256 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormal pyramidal sign (HP:0007256). HP:0007256 is a phenotype from the Human Phenotype Ontology.
Show evidence (2 references)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"Neuroimaging showed hyperintense white matter abnormalities on T2 and fluid attenuated inversion recovery sequences predominantly in the periventricular regions, the posterior limb of the internal capsule, the external capsule, and the pyramidal tracts and medial lemniscus of the pons and medulla."
Pyramidal tract imaging abnormalities support pyramidal signs in APBD.
ORPHA:206583 SUPPORT Other
"| HP:0007256 | Abnormal pyramidal sign | Very frequent (99-80%) |"
Orphanet lists abnormal pyramidal signs as very frequent.
Abnormality of extrapyramidal motor function OCCASIONAL HP:0002071 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Abnormality of extrapyramidal motor function (HP:0002071). HP:0002071 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0002071 | Abnormality of extrapyramidal motor function | Occasional (29-5%) |"
Orphanet lists extrapyramidal motor abnormality as occasional.
Urinary bladder sphincter dysfunction VERY_FREQUENT HP:0002839 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is Urinary bladder sphincter dysfunction (HP:0002839). HP:0002839 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0002839 | Urinary bladder sphincter dysfunction | Very frequent (99-80%) |"
Orphanet lists urinary bladder sphincter dysfunction as very frequent.
EMG abnormality OCCASIONAL HP:0003457 Human Phenotype Ontology (HP) Relation: this clinical feature is this phenotype This clinical feature is EMG abnormality (HP:0003457). HP:0003457 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
ORPHA:206583 SUPPORT Other
"| HP:0003457 | EMG abnormality | Occasional (29-5%) |"
Orphanet lists EMG abnormality as occasional.
🧬

Genetic Associations

1
GBE1 (Causative)
Gene: GBE1 hgnc:4180 HUGO Gene Nomenclature Committee (hgnc) Relation: this disease-associated gene is this gene This disease-associated gene is GBE1 (hgnc:4180). hgnc:4180 is a gene from the HUGO Gene Nomenclature Committee.
Show evidence (2 references)
ORPHA:206583 SUPPORT Other
"| GBE1 | 1,4-alpha-glucan branching enzyme 1 | hgnc:4180 | Disease-causing germline mutation(s) in |"
Orphanet lists GBE1 as a disease-causing gene for APBD.
PMID:33141444 SUPPORT Other
"pathogenic variants in GBE1 gene, resulting in deficiency of glycogen-branching enzyme and secondary storage of glycogen in the form of polyglucosan bodies"
This directly supports GBE1 as the causal APBD gene.
💊

Medical Actions

6
Supportive multidisciplinary care
Action: supportive careNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is supportive care (NCIT:C15747). NCIT:C15747 is a clinical intervention from the NCI Thesaurus. Ontology label: Supportive Care NCIT:C15747
Supportive management is symptom-directed and includes longitudinal monitoring, functional and neuromusculoskeletal assessment, and care for neurologic, bladder, cardiac, skeletal muscle, liver, and other GSD IV manifestations.
Target Phenotypes: Neurogenic bladder HP:0000011 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Neurogenic bladder (HP:0000011). HP:0000011 is a phenotype from the Human Phenotype Ontology. Gait disturbance HP:0001288 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Gait disturbance (HP:0001288). HP:0001288 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:36796138 SUPPORT Other
"The educational resource includes practical steps to confirm a GSD IV diagnosis and best practices for medical management, including (a) imaging of the liver, heart, skeletal muscle, brain, and spine, (b) functional and neuromusculoskeletal assessments, (c) laboratory investigations, (d) liver..."
This supports multidisciplinary supportive management and follow-up for GSD IV/APBD.
Physical therapy
Action: physical therapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is physical therapy (NCIT:C15302). NCIT:C15302 is a clinical intervention from the NCI Thesaurus. Ontology label: Physical Therapy NCIT:C15302
Individualized physical therapy is recommended to improve flexibility, reduce spasticity, maintain or improve joint mobility, and support activities of daily living.
Target Phenotypes: Spasticity HP:0001257 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Spasticity (HP:0001257). HP:0001257 is a phenotype from the Human Phenotype Ontology. Limitation of joint mobility HP:0001376 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Limitation of joint mobility (HP:0001376). HP:0001376 is a phenotype from the Human Phenotype Ontology. Gait disturbance HP:0001288 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Gait disturbance (HP:0001288). HP:0001288 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301758 SUPPORT Other
"An individualized physical therapy program can improve flexibility, reduce spasticity, maintain or improve joint mobility"
GeneReviews recommends individualized physical therapy for flexibility, spasticity, and joint mobility.
Anticholinergic bladder pharmacotherapy
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Agent: anticholinergic agent NCIT:C66880 NCI Thesaurus (NCIT) Relation: this treatment uses this therapeutic agent This treatment uses anticholinergic agent (NCIT:C66880). NCIT:C66880 is a therapeutic agent from the NCI Thesaurus.
Anticholinergic drugs may be used as symptom-directed management for spastic bladder in GBE1-APBD.
Target Phenotypes: Neurogenic bladder HP:0000011 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Neurogenic bladder (HP:0000011). HP:0000011 is a phenotype from the Human Phenotype Ontology. Urinary bladder sphincter dysfunction HP:0002839 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Urinary bladder sphincter dysfunction (HP:0002839). HP:0002839 is a phenotype from the Human Phenotype Ontology. Urinary incontinence HP:0000020 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Urinary incontinence (HP:0000020). HP:0000020 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301758 SUPPORT Other
"Spastic bladder may be managed with anticholinergic drugs"
GeneReviews supports anticholinergic drugs for spastic bladder management.
Bladder catheterization
Action: catheterizationNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is catheterization, annotated with Therapeutic Procedure (NCIT:C49236). NCIT:C49236 is a clinical intervention from the NCI Thesaurus. Ontology label: Therapeutic Procedure NCIT:C49236
Clean intermittent catheterization or an indwelling bladder catheter may be used to prevent urosepsis in spastic bladder.
Target Phenotypes: Neurogenic bladder HP:0000011 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Neurogenic bladder (HP:0000011). HP:0000011 is a phenotype from the Human Phenotype Ontology. Urinary bladder sphincter dysfunction HP:0002839 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Urinary bladder sphincter dysfunction (HP:0002839). HP:0002839 is a phenotype from the Human Phenotype Ontology. Urinary incontinence HP:0000020 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Urinary incontinence (HP:0000020). HP:0000020 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:20301758 SUPPORT Other
"clean intermittent catheterization or an indwelling bladder catheter to prevent urosepsis"
GeneReviews supports catheterization approaches for spastic bladder management.
Genetic counseling
Action: Genetic CounselingNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Genetic Counseling (NCIT:C15240). NCIT:C15240 is a clinical intervention from the NCI Thesaurus. NCIT:C15240
Genetic counseling informs autosomal recessive recurrence risk and options for carrier, prenatal, and preimplantation genetic testing once familial GBE1 variants are known.
Show evidence (2 references)
PMID:20301758 SUPPORT Other
"GBE1-APBD is inherited in an autosomal recessive manner."
GeneReviews supports genetic counseling for autosomal recessive GBE1-APBD.
PMID:20301758 SUPPORT Other
"Once the GBE1 pathogenic variants have been identified in the family, carrier testing for at-risk relatives and prenatal and preimplantation genetic testing for GBE1-APBD are possible."
GeneReviews directly supports carrier, prenatal, and preimplantation testing once familial variants are known.
Triheptanoin pharmacotherapy trial
Action: PharmacotherapyNCI Thesaurus (NCIT) Relation: this treatment is this clinical intervention This treatment is Pharmacotherapy (NCIT:C15986). NCIT:C15986 is a clinical intervention from the NCI Thesaurus. NCIT:C15986
Triheptanoin was tested as an anaplerotic therapy for APBD, but the randomized crossover trial did not establish efficacy over six months despite acceptable safety.
Target Phenotypes: Gait disturbance HP:0001288 Human Phenotype Ontology (HP) Relation: this treatment targets this phenotype This treatment targets Gait disturbance (HP:0001288). HP:0001288 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
PMID:29110179 REFUTE Human Clinical
"We cannot conclude that triheptanoin was effective in the treatment of APBD over a 6-month period, but we found it had a good safety profile."
This refutes proven efficacy while documenting the completed treatment trial and safety signal.
🔬

Biochemical Markers

1
Reduced glycogen branching enzyme activity (DECREASED)
Context: Reduced or deficient GBE1 glycogen branching enzyme activity is the proximal biochemical abnormality that drives poorly branched glycogen storage.
Show evidence (1 reference)
PMID:36796138 SUPPORT Other
"reduced or deficient glycogen branching enzyme activity."
Clinical practice resource identifies deficient glycogen branching enzyme activity in GSD IV/APBD.
🔬

Diagnosis

2
GBE1 molecular genetic testing
Molecular testing for biallelic GBE1 pathogenic variants confirms the diagnosis and can identify deep intronic founder alleles missed by exon-only testing.
molecular genetic testing NCIT:C19770 NCI Thesaurus (NCIT)
Results: Biallelic pathogenic GBE1 variants.
Show evidence (2 references)
PMID:20301758 SUPPORT Other
"The diagnosis of GBE1-APBD is established in a proband with suggestive findings and biallelic GBE1 pathogenic variants identified by molecular genetic testing."
GeneReviews directly supports molecular confirmation with biallelic GBE1 pathogenic variants.
PMID:25665141 SUPPORT Human Clinical
"When we reverse transcribed and sequenced the mRNA of GBE1, we found that all manifesting heterozygous patients had the c.986A>C mutant mRNA and complete lack of mRNA encoded by the second allele."
This supports GBE1 molecular testing, including RNA-level analysis for deep intronic variants.
Brain and spine magnetic resonance imaging
Brain and spine MRI can show characteristic white matter abnormalities, pyramidal tract involvement, and universal medulla/spinal atrophy.
magnetic resonance imaging procedure NCIT:C16809 NCI Thesaurus (NCIT)
Results: T2/FLAIR white matter abnormalities and medulla/spinal atrophy.
Show evidence (2 references)
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"Neuroimaging showed hyperintense white matter abnormalities on T2 and fluid attenuated inversion recovery sequences predominantly in the periventricular regions, the posterior limb of the internal capsule, the external capsule, and the pyramidal tracts and medial lemniscus of the pons and medulla."
The natural-history cohort directly supports the characteristic brain MRI pattern used in diagnostic assessment.
DOI:10.1002/ana.23598 SUPPORT Human Clinical
"Atrophy of the medulla and spine was universal."
This supports medulla and spinal atrophy as a characteristic MRI finding.
🔬

Clinical Trials

1
NCT00947960 PHASE_II COMPLETED
Randomized controlled phase 2 study testing triheptanoin for APBD symptoms.
Target Phenotypes: Gait disturbance HP:0001288 Human Phenotype Ontology (HP) Relation: this clinical trial targets this phenotype This clinical trial targets Gait disturbance (HP:0001288). HP:0001288 is a phenotype from the Human Phenotype Ontology.
Show evidence (1 reference)
clinicaltrials:NCT00947960 SUPPORT Human Clinical
"The purpose of the study is to determine if triheptanoin is an effective treatment for the symptoms of Adult Polyglucosan Body Disease."
This identifies the APBD triheptanoin interventional trial.
{ }

Source YAML

click to show 
name: Adult Polyglucosan Body Disease
creation_date: "2026-05-07T18:30:00Z"
category: Mendelian
description: >-
  Adult polyglucosan body disease is an autosomal recessive, adult-onset
  GBE1-related glycogen storage disease in which deficient glycogen branching
  enzyme activity causes poorly branched glycogen, polyglucosan body
  accumulation, progressive neurogenic bladder, spastic gait, peripheral
  neuropathy, and variable cognitive decline.
synonyms:
- APBD
- polyglucosan body disease, adult
- polyglucosan body neuropathy, adult form
disease_term:
  preferred_term: adult polyglucosan body disease
  term:
    id: MONDO:0009897
    label: adult polyglucosan body disease
parents:
- glycogen storage disease due to glycogen branching enzyme deficiency
- hereditary peripheral neuropathy
inheritance:
- name: Autosomal recessive inheritance
  inheritance_term:
    preferred_term: Autosomal recessive inheritance
    term:
      id: HP:0000007
      label: Autosomal recessive inheritance
  description: >-
    Adult polyglucosan body disease is inherited in an autosomal recessive
    manner due to biallelic pathogenic variants in GBE1.
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "- Autosomal recessive"
    explanation: Orphanet lists autosomal recessive inheritance for APBD.
  - reference: PMID:33141444
    reference_title: "GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Adult polyglucosan body disease (APBD) represents a complex autosomal
      recessive inherited neurometabolic disorder due to homozygous or compound
      heterozygous pathogenic variants in GBE1 gene
    explanation: This review directly states autosomal recessive inheritance and biallelic GBE1 variants.
pathophysiology:
- name: GBE1 deficiency and impaired glycogen branching
  description: >-
    Pathogenic GBE1 variants reduce glycogen branching enzyme activity,
    impairing glycogen synthesis and producing poorly branched glycogen.
  genes:
  - preferred_term: GBE1
    term:
      id: hgnc:4180
      label: GBE1
  biological_processes:
  - preferred_term: glycogen biosynthetic process
    term:
      id: GO:0005978
      label: glycogen biosynthetic process
    modifier: DECREASED
  - preferred_term: glycogen metabolic process
    term:
      id: GO:0005977
      label: glycogen metabolic process
    modifier: ABNORMAL
  molecular_functions:
  - preferred_term: 1,4-alpha-glucan branching enzyme activity
    term:
      id: GO:0003844
      label: 1,4-alpha-glucan branching enzyme activity
    modifier: DECREASED
  chemical_entities:
  - preferred_term: glycogen
    term:
      id: CHEBI:28087
      label: glycogen
    modifier: ABNORMAL
  downstream:
  - target: Polyglucosan body accumulation
    causal_link_type: DIRECT
    description: >-
      Impaired glycogen branching leads to accumulation of poorly branched
      glycogen known as polyglucosan.
    evidence:
    - reference: PMID:36796138
      reference_title: "Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        Consequently, glycogen synthesis is impaired and leads to accumulation
        of poorly branched glycogen known as polyglucosan.
      explanation: The clinical practice resource directly links impaired glycogen synthesis to polyglucosan accumulation.
  - target: Reduced glycogen branching enzyme activity
    causal_link_type: DIRECT
    description: >-
      Pathogenic GBE1 variants reduce or abolish glycogen branching enzyme
      activity.
    evidence:
    - reference: PMID:36796138
      reference_title: "Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        reduced or deficient glycogen branching enzyme activity.
      explanation: Clinical practice resource identifies reduced or deficient glycogen branching enzyme activity in GSD IV/APBD.
  evidence:
  - reference: PMID:36796138
    reference_title: "Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Glycogen storage disease type IV (GSD IV) is an ultra-rare autosomal
      recessive disorder caused by pathogenic variants in GBE1 which results in
      reduced or deficient glycogen branching enzyme activity.
    explanation: This directly supports GBE1 variants causing reduced glycogen branching enzyme activity.
  - reference: PMID:25665141
    reference_title: Deep intronic GBE1 mutation in manifesting heterozygous patients with adult polyglucosan body disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We identified a deep intronic mutation in this allele,
      GBE1-IVS15+5289_5297delGTGTGGTGGinsTGTTTTTTACATGACAGGT, which acts as a
      gene trap, creating an ectopic last exon.
    explanation: This supports pathogenic GBE1 variants as molecular causes of APBD.
- name: Polyglucosan body accumulation
  description: >-
    Deficient glycogen branching enzyme activity causes storage of abnormal
    glycogen as polyglucosan bodies in central nervous system, peripheral nerve,
    autonomic fibers, and skeletal muscle tissues.
  biological_processes:
  - preferred_term: glycogen metabolic process
    term:
      id: GO:0005977
      label: glycogen metabolic process
    modifier: ABNORMAL
  chemical_entities:
  - preferred_term: poorly branched glycogen
    term:
      id: CHEBI:28087
      label: glycogen
    modifier: INCREASED
  downstream:
  - target: Peripheral nerve, autonomic, and neuromuscular involvement
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Polyglucosan storage involves peripheral nerve, autonomic fibers, and
      skeletal muscle, providing a shared branch for bladder, neuropathic,
      sensory, weakness, and mobility-complication phenotypes, with EMG modeled
      separately as an observational readout.
    evidence:
    - reference: PMID:33141444
      reference_title: "GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        deficiency of glycogen-branching enzyme and secondary storage of glycogen
        in the form of polyglucosan bodies, involving the skeletal muscle,
        diaphragm, peripheral nerve (including autonomic fibers), brain white
        matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser
        extent heart, lung, kidney, and liver cells.
      explanation: Clinical review supports peripheral nerve, autonomic, and skeletal muscle involvement downstream of polyglucosan storage.
  - target: White matter and motor tract degeneration
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Polyglucosan storage involves brain white matter, spinal cord, and
      brainstem motor pathways, connecting storage pathology to white matter and
      motor tract degeneration.
    evidence:
    - reference: PMID:33141444
      reference_title: "GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        deficiency of glycogen-branching enzyme and secondary storage of glycogen
        in the form of polyglucosan bodies, involving the skeletal muscle,
        diaphragm, peripheral nerve (including autonomic fibers), brain white
        matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser
        extent heart, lung, kidney, and liver cells.
      explanation: >-
        The review places polyglucosan storage in white matter, spinal cord, and
        brainstem, supporting this anatomic branch but not proving that storage
        alone causes the observed degeneration.
  - target: Proteostasis and cellular stress dysregulation
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      APBD polyglucosan storage and GBE1 deficiency are associated with secondary
      cellular stress and proteostasis pathway dysregulation in patient-derived
      lymphoblasts.
    evidence:
    - reference: DOI:10.3389/fneur.2023.1261125
      reference_title: "Proteomic investigations of adult polyglucosan body disease: insights into the pathobiology of a neurodegenerative disorder"
      supports: SUPPORT
      evidence_source: IN_VITRO
      snippet: >-
        Dysregulation of these processes, therefore, are primary or secondary
        factors in APBD pathobiology in this model system.
      explanation: >-
        Patient-derived lymphoblasts support an APBD-associated pathway branch,
        but the study does not establish whether polyglucosan accumulation is
        upstream or whether the same changes occur in affected nervous tissue.
  evidence:
  - reference: PMID:33141444
    reference_title: "GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      deficiency of glycogen-branching enzyme and secondary storage of glycogen
      in the form of polyglucosan bodies, involving the skeletal muscle,
      diaphragm, peripheral nerve (including autonomic fibers), brain white
      matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser
      extent heart, lung, kidney, and liver cells.
    explanation: This directly supports the affected tissues and polyglucosan storage mechanism.
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Polyglucosan bodies accumulate in the central and peripheral nervous
      systems and are often associated with glycogen branching enzyme (GBE)
      deficiency.
    explanation: This links GBE deficiency to polyglucosan body accumulation in central and peripheral nervous systems.
- name: Peripheral nerve, autonomic, and neuromuscular involvement
  description: >-
    APBD storage pathology affects peripheral nerves, autonomic fibers, nerve
    roots, and skeletal muscle, producing bladder sphincter dysfunction,
    neuropathy with distal sensory impairment, weakness, and secondary mobility
    or skin complications. Electromyography is represented separately as an
    observational readout of this tissue branch.
  biological_processes:
  - preferred_term: transmission of nerve impulse
    term:
      id: GO:0019226
      label: transmission of nerve impulse
    modifier: ABNORMAL
  evidence:
  - reference: PMID:33141444
    reference_title: "GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      deficiency of glycogen-branching enzyme and secondary storage of glycogen
      in the form of polyglucosan bodies, involving the skeletal muscle,
      diaphragm, peripheral nerve (including autonomic fibers), brain white
      matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser
      extent heart, lung, kidney, and liver cells.
    explanation: Clinical review supports the affected peripheral, autonomic, and neuromuscular tissues.
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most common clinical findings were neurogenic bladder (100%), spastic
      paraplegia with vibration loss (90%), and axonal neuropathy (90%).
    explanation: Natural history cohort supports autonomic bladder involvement, vibration loss, and axonal neuropathy.
  - reference: PMID:20301758
    reference_title: "GBE1 Adult Polyglucosan Body Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      neurogenic bladder, gait difficulties (i.e., spasticity and weakness) from
      mixed upper and lower motor neuron involvement, sensory loss predominantly
      in the distal lower extremities, autonomic dysfunction
    explanation: GeneReviews summarizes the same bladder, motor, sensory, and autonomic involvement in classic GBE1-APBD.
  downstream:
  - target: Neurogenic bladder
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Neurogenic bladder is linked conservatively to the combined peripheral,
      autonomic, and neuromuscular branch because the cohort does not distinguish
      autonomic fiber pathology from central bladder-pathway involvement.
    evidence:
    - reference: DOI:10.1002/ana.23598
      reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The most common clinical findings were neurogenic bladder (100%),
        spastic paraplegia with vibration loss (90%), and axonal neuropathy
        (90%).
      explanation: >-
        The cohort supports neurogenic bladder alongside peripheral neuropathy,
        but it does not resolve which neural compartment mediates the bladder
        phenotype.
  - target: Urinary incontinence
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Neurogenic bladder and autonomic dysfunction lead to urinary incontinence.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0000020 | Urinary incontinence | Very frequent (99-80%) |"
      explanation: >-
        Orphanet supports urinary incontinence as an APBD phenotype but does not
        establish the proposed autonomic route.
  - target: Urinary bladder sphincter dysfunction
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Autonomic and bladder pathway involvement produces bladder sphincter dysfunction.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0002839 | Urinary bladder sphincter dysfunction | Very frequent (99-80%) |"
      explanation: >-
        Orphanet supports bladder sphincter dysfunction as an APBD phenotype but
        does not establish the proposed autonomic route.
  - target: Orthostatic hypotension
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Autonomic dysfunction in classic GBE1-APBD can include orthostatic hypotension.
    evidence:
    - reference: PMID:20301758
      reference_title: "GBE1 Adult Polyglucosan Body Disease."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "autonomic dysfunction (associated with orthostatic hypotension and constipation)"
      explanation: GeneReviews links APBD autonomic dysfunction to orthostatic hypotension.
  - target: Constipation
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Autonomic dysfunction in classic GBE1-APBD can include constipation.
    evidence:
    - reference: PMID:20301758
      reference_title: "GBE1 Adult Polyglucosan Body Disease."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "autonomic dysfunction (associated with orthostatic hypotension and constipation)"
      explanation: GeneReviews links APBD autonomic dysfunction to constipation.
  - target: Peripheral neuropathy
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Peripheral neuropathy is linked to this tissue-involvement branch, while
      the intervening injury process remains unresolved in the cached cohort.
    evidence:
    - reference: DOI:10.1002/ana.23598
      reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The most common clinical findings were neurogenic bladder (100%),
        spastic paraplegia with vibration loss (90%), and axonal neuropathy
        (90%).
      explanation: >-
        The cohort supports common axonal neuropathy in APBD but does not directly
        test the causal route from polyglucosan involvement of peripheral nerve.
  - target: Peripheral axonal neuropathy
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Peripheral nerve storage pathology produces axonal neuropathy.
    evidence:
    - reference: DOI:10.1002/ana.23598
      reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The most common clinical findings were neurogenic bladder (100%),
        spastic paraplegia with vibration loss (90%), and axonal neuropathy
        (90%).
      explanation: >-
        The cohort identifies axonal neuropathy as common in APBD but does not
        directly test the proposed tissue-to-phenotype route.
  - target: Distal sensory impairment
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Axonal neuropathy with vibration loss produces distal sensory impairment.
    evidence:
    - reference: DOI:10.1002/ana.23598
      reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The most common clinical findings were neurogenic bladder (100%),
        spastic paraplegia with vibration loss (90%), and axonal neuropathy
        (90%).
      explanation: >-
        Vibration loss supports sensory impairment in APBD but only partially
        supports its placement downstream of this combined tissue branch.
  - target: Muscle weakness
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Skeletal muscle and neuromuscular involvement can manifest as weakness.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0001324 | Muscle weakness | Very frequent (99-80%) |"
      explanation: >-
        Orphanet supports muscle weakness as an APBD phenotype but does not
        resolve the proposed neuromuscular route.
  - target: Limitation of joint mobility
    causal_link_type: UNKNOWN
    description: Reduced mobility and neuromuscular disease may contribute to joint mobility limitation.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0001376 | Limitation of joint mobility | Occasional (29-5%) |"
      explanation: >-
        Orphanet supports joint-mobility limitation as an APBD phenotype but not
        the proposed secondary mobility mechanism.
  - target: Skin ulcer
    causal_link_type: UNKNOWN
    description: Skin ulcers are modeled as a secondary complication of neuropathy or reduced mobility.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0200042 | Skin ulcer | Frequent (79-30%) |"
      explanation: >-
        Orphanet supports skin ulcer as an APBD phenotype but not the proposed
        secondary neuropathy or reduced-mobility mechanism.
- name: White matter and motor tract degeneration
  description: >-
    APBD neuroimaging shows white matter abnormalities and medulla/spinal
    atrophy involving motor tracts, consistent with progressive spastic gait and
    pyramidal signs.
  downstream:
  - target: Gait disturbance
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Motor-tract involvement is linked to the characteristic gait disturbance,
      although the cached phenotype record does not test this causal route.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0001288 | Gait disturbance | Very frequent (99-80%) |"
      explanation: >-
        Orphanet supports gait disturbance as a frequent APBD phenotype but does
        not establish its placement downstream of motor-tract degeneration.
  - target: Spasticity
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Central motor-tract involvement is linked to the characteristic spastic
      motor phenotype.
    evidence:
    - reference: PMID:36796138
      reference_title: "Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource."
      supports: SUPPORT
      evidence_source: OTHER
      snippet: >-
        The adult-onset form of GSD IV, referred to as adult polyglucosan body
        disease (APBD), is a neurodegenerative disease characterized by
        neurogenic bladder, spastic paraparesis, and peripheral neuropathy.
      explanation: >-
        The practice resource supports spastic paraparesis as characteristic of
        APBD but does not directly test the proposed motor-tract route.
  - target: Spastic paraplegia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Motor tract involvement produces spastic paraplegia in APBD.
    evidence:
    - reference: DOI:10.1002/ana.23598
      reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        The most common clinical findings were neurogenic bladder (100%),
        spastic paraplegia with vibration loss (90%), and axonal neuropathy
        (90%).
      explanation: >-
        The cohort reports spastic paraplegia in APBD but does not directly test
        its placement downstream of motor-tract degeneration.
  - target: Abnormal pyramidal sign
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: >-
      Pyramidal-tract involvement is linked to upper motor neuron signs, while
      the APBD-specific causal step is inferred from imaging and phenotype data.
    evidence:
    - reference: DOI:10.1002/ana.23598
      reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Neuroimaging showed hyperintense white matter abnormalities on T2 and
        fluid attenuated inversion recovery sequences predominantly in the
        periventricular regions, the posterior limb of the internal capsule,
        the external capsule, and the pyramidal tracts and medial lemniscus of
        the pons and medulla.
      explanation: >-
        Imaging directly supports pyramidal-tract involvement, but the abstract
        does not explicitly link those abnormalities to pyramidal signs.
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0007256 | Abnormal pyramidal sign | Very frequent (99-80%) |"
      explanation: >-
        Orphanet supports abnormal pyramidal signs as an APBD phenotype but does
        not establish their mechanistic route.
  - target: Abnormal cerebral white matter morphology
    causal_link_type: DIRECT
    description: APBD neuroimaging demonstrates cerebral white matter abnormalities.
    evidence:
    - reference: DOI:10.1002/ana.23598
      reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: >-
        Neuroimaging showed hyperintense white matter abnormalities on T2 and
        fluid attenuated inversion recovery sequences predominantly in the
        periventricular regions, the posterior limb of the internal capsule, the
        external capsule, and the pyramidal tracts and medial lemniscus of the
        pons and medulla.
      explanation: The cohort directly reports cerebral white matter abnormalities on MRI.
  - target: Dementia
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: >-
      Dementia is linked conservatively to central nervous system degeneration;
      the cached evidence does not isolate a white-matter-mediated route.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0000726 | Dementia | Occasional (29-5%) |"
      explanation: >-
        Orphanet supports dementia as an occasional APBD phenotype but does not
        establish that white-matter or motor-tract degeneration causes it.
  - target: Ataxia
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Cerebellar and brainstem involvement can produce ataxia.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0001251 | Ataxia | Occasional (29-5%) |"
      explanation: >-
        Orphanet supports ataxia as an APBD phenotype but does not establish the
        proposed cerebellar or brainstem route.
  - target: Atypical behavior
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: White matter and cognitive involvement can be accompanied by behavioral changes.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0000708 | Atypical behavior | Frequent (79-30%) |"
      explanation: >-
        Orphanet supports atypical behavior as an APBD phenotype but does not
        establish a white-matter-mediated route.
  - target: Intellectual disability
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
    description: APBD cognitive involvement is linked conservatively to the Orphanet intellectual disability phenotype.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0001249 | Intellectual disability | Very frequent (99-80%) |"
      explanation: >-
        Orphanet supports this phenotype association but does not establish a
        white-matter-mediated route.
  - target: Hemiparesis
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
    description: Motor tract degeneration can produce paresis phenotypes.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0001269 | Hemiparesis | Very frequent (99-80%) |"
      explanation: >-
        Orphanet supports hemiparesis as an APBD phenotype but does not directly
        test the proposed motor-tract route.
  - target: Abnormality of extrapyramidal motor function
    causal_link_type: UNKNOWN
    description: Orphanet lists extrapyramidal motor involvement, but cached evidence does not resolve the intermediate mechanism.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0002071 | Abnormality of extrapyramidal motor function | Occasional (29-5%) |"
      explanation: >-
        Orphanet supports extrapyramidal motor abnormality as an APBD phenotype
        but does not resolve its intermediate mechanism.
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Neuroimaging showed hyperintense white matter abnormalities on T2 and
      fluid attenuated inversion recovery sequences predominantly in the
      periventricular regions, the posterior limb of the internal capsule, the
      external capsule, and the pyramidal tracts and medial lemniscus of the
      pons and medulla.
    explanation: This directly supports white matter and motor tract involvement in APBD.
- name: Proteostasis and cellular stress dysregulation
  description: >-
    Human APBD lymphoblast proteomics implicates secondary dysregulation of
    protein ubiquitination, unfolded protein and endoplasmic reticulum stress
    responses, TOR signaling, glycolysis, and cell death pathways.
  biological_processes:
  - preferred_term: protein ubiquitination
    term:
      id: GO:0016567
      label: protein ubiquitination
    modifier: ABNORMAL
  - preferred_term: response to endoplasmic reticulum stress
    term:
      id: GO:0034976
      label: response to endoplasmic reticulum stress
    modifier: ABNORMAL
  - preferred_term: TOR signaling
    term:
      id: GO:0031929
      label: TOR signaling
    modifier: ABNORMAL
  evidence:
  - reference: DOI:10.3389/fneur.2023.1261125
    reference_title: "Proteomic investigations of adult polyglucosan body disease: insights into the pathobiology of a neurodegenerative disorder"
    supports: SUPPORT
    evidence_source: IN_VITRO
    snippet: >-
      Bioinformatic analyses indicated multiple canonical pathways and
      protein–protein interaction networks to be statistically markedly
      enriched in APBD subjects, including: RNA processing/transport/translation,
      cell cycle control/replication, mTOR signaling, protein ubiquitination,
      unfolded protein and endoplasmic reticulum stress responses, glycolysis
      and cell death/apoptosis.
    explanation: >-
      This small lymphoblast discovery study supports APBD-associated cellular
      stress and proteostasis dysregulation, with tissue and causal-direction
      limitations.
histopathology:
- name: Polyglucosan bodies in nervous system and skeletal muscle
  finding_term:
    preferred_term: Morphologic Finding
    term:
      id: NCIT:C35867
      label: Morphologic Finding
  description: >-
    APBD is histologically characterized by structurally abnormal glycogen
    deposits, or polyglucosan bodies, in multiple nervous system and
    neuromuscular cell types.
  evidence:
  - reference: PMID:33141444
    reference_title: "GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      deficiency of glycogen-branching enzyme and secondary storage of glycogen
      in the form of polyglucosan bodies, involving the skeletal muscle,
      diaphragm, peripheral nerve (including autonomic fibers), brain white
      matter, spinal cord, nerve roots, cerebellum, brainstem and to a lesser
      extent heart, lung, kidney, and liver cells.
    explanation: >-
      This clinical review supports polyglucosan body storage across nervous
      system and skeletal muscle tissues as the characteristic histopathologic
      feature.
phenotypes:
- category: Genitourinary
  name: Neurogenic bladder
  frequency: VERY_FREQUENT
  description: >-
    Neurogenic bladder is usually the earliest and most penetrant APBD clinical
    manifestation.
  phenotype_term:
    preferred_term: Neurogenic bladder
    term:
      id: HP:0000011
      label: Neurogenic bladder
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most common clinical findings were neurogenic bladder (100%), spastic
      paraplegia with vibration loss (90%), and axonal neuropathy (90%).
    explanation: This directly supports neurogenic bladder as a very frequent APBD phenotype.
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0000011 | Neurogenic bladder | Very frequent (99-80%) |"
    explanation: Orphanet lists neurogenic bladder as very frequent.
- category: Genitourinary
  name: Urinary incontinence
  frequency: VERY_FREQUENT
  description: >-
    Urinary incontinence and other bladder sphincter symptoms occur downstream
    of APBD autonomic and central nervous system involvement.
  phenotype_term:
    preferred_term: Urinary incontinence
    term:
      id: HP:0000020
      label: Urinary incontinence
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0000020 | Urinary incontinence | Very frequent (99-80%) |"
    explanation: Orphanet lists urinary incontinence as very frequent.
- category: Neurologic
  name: Spasticity
  frequency: VERY_FREQUENT
  description: >-
    Progressive spasticity and spastic paraparesis are core motor features of
    APBD.
  phenotype_term:
    preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0001257 | Spasticity | Very frequent (99-80%) |"
    explanation: Orphanet lists spasticity as very frequent.
  - reference: PMID:36796138
    reference_title: "Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The adult-onset form of GSD IV, referred to as adult polyglucosan body
      disease (APBD), is a neurodegenerative disease characterized by neurogenic
      bladder, spastic paraparesis, and peripheral neuropathy.
    explanation: This directly supports spastic paraparesis as a characteristic feature.
- category: Neurologic
  name: Spastic paraplegia
  frequency: VERY_FREQUENT
  description: >-
    Spastic paraplegia is a common motor manifestation of APBD.
  phenotype_term:
    preferred_term: Spastic paraplegia
    term:
      id: HP:0001258
      label: Spastic paraplegia
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most common clinical findings were neurogenic bladder (100%), spastic
      paraplegia with vibration loss (90%), and axonal neuropathy (90%).
    explanation: This directly supports spastic paraplegia as a very frequent APBD phenotype.
- category: Neurologic
  name: Gait disturbance
  frequency: VERY_FREQUENT
  description: >-
    Progressive spastic gait leads to loss of ambulation and wheelchair
    dependence in many patients.
  phenotype_term:
    preferred_term: Gait disturbance
    term:
      id: HP:0001288
      label: Gait disturbance
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The median age was 51 years for the onset of neurogenic bladder symptoms,
      63 years for wheelchair dependence, and 70 years for death.
    explanation: Wheelchair dependence supports progressive gait disability in APBD.
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0001288 | Gait disturbance | Very frequent (99-80%) |"
    explanation: Orphanet lists gait disturbance as very frequent.
- category: Neurologic
  name: Peripheral neuropathy
  frequency: VERY_FREQUENT
  description: >-
    APBD commonly causes axonal peripheral neuropathy with distal sensory loss.
  phenotype_term:
    preferred_term: Peripheral neuropathy
    term:
      id: HP:0009830
      label: Peripheral neuropathy
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most common clinical findings were neurogenic bladder (100%), spastic
      paraplegia with vibration loss (90%), and axonal neuropathy (90%).
    explanation: This directly supports axonal neuropathy as very frequent.
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0009830 | Peripheral neuropathy | Very frequent (99-80%) |"
    explanation: Orphanet lists peripheral neuropathy as very frequent.
- category: Neurologic
  name: Peripheral axonal neuropathy
  frequency: VERY_FREQUENT
  description: >-
    Peripheral neuropathy in APBD is commonly axonal.
  phenotype_term:
    preferred_term: Peripheral axonal neuropathy
    term:
      id: HP:0003477
      label: Peripheral axonal neuropathy
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most common clinical findings were neurogenic bladder (100%), spastic
      paraplegia with vibration loss (90%), and axonal neuropathy (90%).
    explanation: This directly supports axonal neuropathy as a very frequent APBD phenotype.
- category: Neurologic
  name: Distal sensory impairment
  frequency: FREQUENT
  description: >-
    Distal vibration and sensory loss accompanies APBD neuropathy.
  phenotype_term:
    preferred_term: Distal sensory impairment
    term:
      id: HP:0002936
      label: Distal sensory impairment
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The most common clinical findings were neurogenic bladder (100%), spastic
      paraplegia with vibration loss (90%), and axonal neuropathy (90%).
    explanation: Vibration loss supports distal sensory impairment in APBD.
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0002936 | Distal sensory impairment | Frequent (79-30%) |"
    explanation: Orphanet lists distal sensory impairment as frequent.
- category: Neurologic
  name: Abnormal pyramidal sign
  frequency: VERY_FREQUENT
  description: >-
    Pyramidal tract involvement produces upper motor neuron signs and spastic
    paraparesis.
  phenotype_term:
    preferred_term: Abnormal pyramidal sign
    term:
      id: HP:0007256
      label: Abnormal pyramidal sign
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Neuroimaging showed hyperintense white matter abnormalities on T2 and
      fluid attenuated inversion recovery sequences predominantly in the
      periventricular regions, the posterior limb of the internal capsule, the
      external capsule, and the pyramidal tracts and medial lemniscus of the
      pons and medulla.
    explanation: Pyramidal tract imaging abnormalities support pyramidal signs in APBD.
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0007256 | Abnormal pyramidal sign | Very frequent (99-80%) |"
    explanation: Orphanet lists abnormal pyramidal signs as very frequent.
- category: Neurologic
  name: Abnormal cerebral white matter morphology
  description: >-
    APBD MRI commonly shows hyperintense cerebral white matter abnormalities.
  phenotype_term:
    preferred_term: Abnormal cerebral white matter morphology
    term:
      id: HP:0002500
      label: Abnormal cerebral white matter morphology
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Neuroimaging showed hyperintense white matter abnormalities on T2 and fluid
      attenuated inversion recovery sequences predominantly in the periventricular
      regions, the posterior limb of the internal capsule, the external capsule,
      and the pyramidal tracts and medial lemniscus of the pons and medulla.
    explanation: This directly supports cerebral white matter abnormalities on APBD MRI.
- category: Neurologic
  name: Muscle weakness
  frequency: VERY_FREQUENT
  description: >-
    Weakness may reflect neuromuscular involvement and contributes to mobility
    limitation in APBD.
  phenotype_term:
    preferred_term: Muscle weakness
    term:
      id: HP:0001324
      label: Muscle weakness
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0001324 | Muscle weakness | Very frequent (99-80%) |"
    explanation: Orphanet lists muscle weakness as very frequent.
- category: Neurologic
  name: Dementia
  frequency: OCCASIONAL
  description: >-
    Cognitive decline can progress to dementia in a subset of adults with APBD.
  phenotype_term:
    preferred_term: Dementia
    term:
      id: HP:0000726
      label: Dementia
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      As the disease progressed, mild cognitive decline may have affected up to
      half of the patients.
    explanation: >-
      This supports acquired cognitive involvement in APBD but does not by itself
      establish dementia; the dementia frequency is supported by Orphanet.
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0000726 | Dementia | Occasional (29-5%) |"
    explanation: Orphanet lists dementia as occasional.
- category: Neurologic
  name: Ataxia
  frequency: OCCASIONAL
  description: >-
    Ataxia is reported less often than spastic gait, bladder dysfunction, and
    neuropathy.
  phenotype_term:
    preferred_term: Ataxia
    term:
      id: HP:0001251
      label: Ataxia
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0001251 | Ataxia | Occasional (29-5%) |"
    explanation: Orphanet lists ataxia as occasional.
- category: Neurobehavioral
  name: Atypical behavior
  frequency: FREQUENT
  description: >-
    Behavioral or psychiatric changes may accompany APBD cognitive involvement.
  phenotype_term:
    preferred_term: Atypical behavior
    term:
      id: HP:0000708
      label: Atypical behavior
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0000708 | Atypical behavior | Frequent (79-30%) |"
    explanation: Orphanet lists atypical behavior as frequent.
- category: Neurologic
  name: Intellectual disability
  frequency: VERY_FREQUENT
  description: >-
    Orphanet maps APBD cognitive involvement to intellectual disability, while
    the natural history cohort more specifically describes adult cognitive
    decline.
  phenotype_term:
    preferred_term: Intellectual disability
    term:
      id: HP:0001249
      label: Intellectual disability
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0001249 | Intellectual disability | Very frequent (99-80%) |"
    explanation: Orphanet lists intellectual disability as very frequent.
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      As the disease progressed, mild cognitive decline may have affected up to
      half of the patients.
    explanation: >-
      The human cohort supports cognitive involvement but describes acquired
      cognitive decline rather than developmental intellectual disability.
- category: Neurologic
  name: Hemiparesis
  frequency: VERY_FREQUENT
  description: >-
    Orphanet lists hemiparesis among APBD motor phenotypes; clinically, APBD
    more often presents with progressive spastic paraparesis and gait
    impairment.
  phenotype_term:
    preferred_term: Hemiparesis
    term:
      id: HP:0001269
      label: Hemiparesis
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0001269 | Hemiparesis | Very frequent (99-80%) |"
    explanation: Orphanet lists hemiparesis as very frequent.
- category: Musculoskeletal
  name: Limitation of joint mobility
  frequency: OCCASIONAL
  description: >-
    Limitation of joint mobility may occur as a secondary musculoskeletal
    complication in APBD.
  phenotype_term:
    preferred_term: Limitation of joint mobility
    term:
      id: HP:0001376
      label: Limitation of joint mobility
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0001376 | Limitation of joint mobility | Occasional (29-5%) |"
    explanation: Orphanet lists limitation of joint mobility as occasional.
- category: Neurologic
  name: Abnormality of extrapyramidal motor function
  frequency: OCCASIONAL
  description: >-
    Extrapyramidal motor findings are listed less often than pyramidal signs
    and spastic gait.
  phenotype_term:
    preferred_term: Abnormality of extrapyramidal motor function
    term:
      id: HP:0002071
      label: Abnormality of extrapyramidal motor function
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0002071 | Abnormality of extrapyramidal motor function | Occasional (29-5%) |"
    explanation: Orphanet lists extrapyramidal motor abnormality as occasional.
- category: Genitourinary
  name: Urinary bladder sphincter dysfunction
  frequency: VERY_FREQUENT
  description: >-
    Bladder sphincter dysfunction is part of the neurogenic bladder/autonomic
    phenotype in APBD.
  phenotype_term:
    preferred_term: Urinary bladder sphincter dysfunction
    term:
      id: HP:0002839
      label: Urinary bladder sphincter dysfunction
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0002839 | Urinary bladder sphincter dysfunction | Very frequent (99-80%) |"
    explanation: Orphanet lists urinary bladder sphincter dysfunction as very frequent.
- category: Cardiovascular
  name: Orthostatic hypotension
  description: >-
    Orthostatic hypotension can occur as part of APBD autonomic dysfunction.
  phenotype_term:
    preferred_term: Orthostatic hypotension
    term:
      id: HP:0001278
      label: Orthostatic hypotension
  evidence:
  - reference: PMID:20301758
    reference_title: "GBE1 Adult Polyglucosan Body Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "autonomic dysfunction (associated with orthostatic hypotension and constipation)"
    explanation: GeneReviews lists orthostatic hypotension as part of APBD autonomic dysfunction.
- category: Gastrointestinal
  name: Constipation
  description: Constipation can occur as part of APBD autonomic dysfunction.
  phenotype_term:
    preferred_term: Constipation
    term:
      id: HP:0002019
      label: Constipation
  evidence:
  - reference: PMID:20301758
    reference_title: "GBE1 Adult Polyglucosan Body Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "autonomic dysfunction (associated with orthostatic hypotension and constipation)"
    explanation: GeneReviews lists constipation as part of APBD autonomic dysfunction.
- category: Neurologic
  name: EMG abnormality
  frequency: OCCASIONAL
  description: >-
    Electromyography may be abnormal in APBD neuromuscular presentations.
  phenotype_term:
    preferred_term: EMG abnormality
    term:
      id: HP:0003457
      label: EMG abnormality
  reports_on:
  - target: Peripheral nerve, autonomic, and neuromuscular involvement
    relationship: READOUT_OF
    direction: POSITIVE
    endpoint_context: DIAGNOSTIC
    interpretation: >-
      Electromyography is a diagnostic readout of neuromuscular involvement,
      not a downstream disease event.
    evidence:
    - reference: ORPHA:206583
      reference_title: Adult polyglucosan body disease
      supports: SUPPORT
      evidence_source: OTHER
      snippet: "| HP:0003457 | EMG abnormality | Occasional (29-5%) |"
      explanation: >-
        Orphanet establishes the APBD phenotype association; this link
        represents an observational readout rather than causal progression.
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0003457 | EMG abnormality | Occasional (29-5%) |"
    explanation: Orphanet lists EMG abnormality as occasional.
- category: Dermatological
  name: Skin ulcer
  frequency: FREQUENT
  description: >-
    Skin ulceration is listed by Orphanet and may reflect complications of
    neuropathy or reduced mobility.
  phenotype_term:
    preferred_term: Skin ulcer
    term:
      id: HP:0200042
      label: Skin ulcer
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| HP:0200042 | Skin ulcer | Frequent (79-30%) |"
    explanation: Orphanet lists skin ulcer as frequent.
biochemical:
- name: Reduced glycogen branching enzyme activity
  presence: DECREASED
  context: >-
    Reduced or deficient GBE1 glycogen branching enzyme activity is the proximal
    biochemical abnormality that drives poorly branched glycogen storage.
  evidence:
  - reference: PMID:36796138
    reference_title: "Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      reduced or deficient glycogen branching enzyme activity.
    explanation: Clinical practice resource identifies deficient glycogen branching enzyme activity in GSD IV/APBD.
genetic:
- name: GBE1
  association: Causative
  gene_term:
    preferred_term: GBE1
    term:
      id: hgnc:4180
      label: GBE1
  evidence:
  - reference: ORPHA:206583
    reference_title: Adult polyglucosan body disease
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "| GBE1 | 1,4-alpha-glucan branching enzyme 1 | hgnc:4180 | Disease-causing germline mutation(s) in |"
    explanation: Orphanet lists GBE1 as a disease-causing gene for APBD.
  - reference: PMID:33141444
    reference_title: "GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      pathogenic variants in GBE1 gene, resulting in deficiency of
      glycogen-branching enzyme and secondary storage of glycogen in the form of
      polyglucosan bodies
    explanation: This directly supports GBE1 as the causal APBD gene.
diagnosis:
- name: GBE1 molecular genetic testing
  description: >-
    Molecular testing for biallelic GBE1 pathogenic variants confirms the
    diagnosis and can identify deep intronic founder alleles missed by exon-only
    testing.
  diagnosis_term:
    preferred_term: molecular genetic testing
    term:
      id: NCIT:C19770
      label: Molecular Analysis
    qualifiers:
    - predicate:
        preferred_term: has participant
        term:
          id: RO:0000057
          label: has participant
      value:
        preferred_term: GBE1
        term:
          id: hgnc:4180
          label: GBE1
  results: Biallelic pathogenic GBE1 variants.
  evidence:
  - reference: PMID:20301758
    reference_title: "GBE1 Adult Polyglucosan Body Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The diagnosis of GBE1-APBD is established in a proband with suggestive
      findings and biallelic GBE1 pathogenic variants identified by molecular
      genetic testing.
    explanation: >-
      GeneReviews directly supports molecular confirmation with biallelic GBE1
      pathogenic variants.
  - reference: PMID:25665141
    reference_title: Deep intronic GBE1 mutation in manifesting heterozygous patients with adult polyglucosan body disease.
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      When we reverse transcribed and sequenced the mRNA of GBE1, we found that
      all manifesting heterozygous patients had the c.986A>C mutant mRNA and
      complete lack of mRNA encoded by the second allele.
    explanation: This supports GBE1 molecular testing, including RNA-level analysis for deep intronic variants.
- name: Brain and spine magnetic resonance imaging
  description: >-
    Brain and spine MRI can show characteristic white matter abnormalities,
    pyramidal tract involvement, and universal medulla/spinal atrophy.
  diagnosis_term:
    preferred_term: magnetic resonance imaging procedure
    term:
      id: NCIT:C16809
      label: Magnetic Resonance Imaging
  results: T2/FLAIR white matter abnormalities and medulla/spinal atrophy.
  evidence:
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Neuroimaging showed hyperintense white matter abnormalities on T2 and
      fluid attenuated inversion recovery sequences predominantly in the
      periventricular regions, the posterior limb of the internal capsule, the
      external capsule, and the pyramidal tracts and medial lemniscus of the pons
      and medulla.
    explanation: >-
      The natural-history cohort directly supports the characteristic brain MRI
      pattern used in diagnostic assessment.
  - reference: DOI:10.1002/ana.23598
    reference_title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      Atrophy of the medulla and spine was universal.
    explanation: This supports medulla and spinal atrophy as a characteristic MRI finding.
treatments:
- name: Supportive multidisciplinary care
  description: >-
    Supportive management is symptom-directed and includes longitudinal
    monitoring, functional and neuromusculoskeletal assessment, and care for
    neurologic, bladder, cardiac, skeletal muscle, liver, and other GSD IV
    manifestations.
  treatment_term:
    preferred_term: supportive care
    term:
      id: NCIT:C15747
      label: Supportive Care
  target_phenotypes:
  - preferred_term: Neurogenic bladder
    term:
      id: HP:0000011
      label: Neurogenic bladder
  - preferred_term: Gait disturbance
    term:
      id: HP:0001288
      label: Gait disturbance
  evidence:
  - reference: PMID:36796138
    reference_title: "Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      The educational resource includes practical steps to confirm a GSD IV
      diagnosis and best practices for medical management, including (a) imaging
      of the liver, heart, skeletal muscle, brain, and spine, (b) functional and
      neuromusculoskeletal assessments, (c) laboratory investigations, (d) liver
      and heart transplantation, and (e) long-term follow-up care.
    explanation: This supports multidisciplinary supportive management and follow-up for GSD IV/APBD.
- name: Physical therapy
  description: >-
    Individualized physical therapy is recommended to improve flexibility,
    reduce spasticity, maintain or improve joint mobility, and support
    activities of daily living.
  therapeutic_modality: BEHAVIORAL
  treatment_term:
    preferred_term: physical therapy
    term:
      id: NCIT:C15302
      label: Physical Therapy
  target_phenotypes:
  - preferred_term: Spasticity
    term:
      id: HP:0001257
      label: Spasticity
  - preferred_term: Limitation of joint mobility
    term:
      id: HP:0001376
      label: Limitation of joint mobility
  - preferred_term: Gait disturbance
    term:
      id: HP:0001288
      label: Gait disturbance
  evidence:
  - reference: PMID:20301758
    reference_title: "GBE1 Adult Polyglucosan Body Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      An individualized physical therapy program can improve flexibility, reduce
      spasticity, maintain or improve joint mobility
    explanation: GeneReviews recommends individualized physical therapy for flexibility, spasticity, and joint mobility.
- name: Anticholinergic bladder pharmacotherapy
  description: >-
    Anticholinergic drugs may be used as symptom-directed management for spastic
    bladder in GBE1-APBD.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
    therapeutic_agent:
    - preferred_term: anticholinergic agent
      term:
        id: NCIT:C66880
        label: Anticholinergic Agent
  target_phenotypes:
  - preferred_term: Neurogenic bladder
    term:
      id: HP:0000011
      label: Neurogenic bladder
  - preferred_term: Urinary bladder sphincter dysfunction
    term:
      id: HP:0002839
      label: Urinary bladder sphincter dysfunction
  - preferred_term: Urinary incontinence
    term:
      id: HP:0000020
      label: Urinary incontinence
  evidence:
  - reference: PMID:20301758
    reference_title: "GBE1 Adult Polyglucosan Body Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "Spastic bladder may be managed with anticholinergic drugs"
    explanation: GeneReviews supports anticholinergic drugs for spastic bladder management.
- name: Bladder catheterization
  description: >-
    Clean intermittent catheterization or an indwelling bladder catheter may be
    used to prevent urosepsis in spastic bladder.
  treatment_term:
    preferred_term: catheterization
    term:
      id: NCIT:C49236
      label: Therapeutic Procedure
  target_phenotypes:
  - preferred_term: Neurogenic bladder
    term:
      id: HP:0000011
      label: Neurogenic bladder
  - preferred_term: Urinary bladder sphincter dysfunction
    term:
      id: HP:0002839
      label: Urinary bladder sphincter dysfunction
  - preferred_term: Urinary incontinence
    term:
      id: HP:0000020
      label: Urinary incontinence
  evidence:
  - reference: PMID:20301758
    reference_title: "GBE1 Adult Polyglucosan Body Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "clean intermittent catheterization or an indwelling bladder catheter to prevent urosepsis"
    explanation: GeneReviews supports catheterization approaches for spastic bladder management.
- name: Genetic counseling
  description: >-
    Genetic counseling informs autosomal recessive recurrence risk and options
    for carrier, prenatal, and preimplantation genetic testing once familial
    GBE1 variants are known.
  treatment_term:
    preferred_term: Genetic Counseling
    term:
      id: NCIT:C15240
      label: Genetic Counseling
  evidence:
  - reference: PMID:20301758
    reference_title: "GBE1 Adult Polyglucosan Body Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: "GBE1-APBD is inherited in an autosomal recessive manner."
    explanation: GeneReviews supports genetic counseling for autosomal recessive GBE1-APBD.
  - reference: PMID:20301758
    reference_title: "GBE1 Adult Polyglucosan Body Disease."
    supports: SUPPORT
    evidence_source: OTHER
    snippet: >-
      Once the GBE1 pathogenic variants have been identified in the family,
      carrier testing for at-risk relatives and prenatal and preimplantation
      genetic testing for GBE1-APBD are possible.
    explanation: >-
      GeneReviews directly supports carrier, prenatal, and preimplantation
      testing once familial variants are known.
- name: Triheptanoin pharmacotherapy trial
  description: >-
    Triheptanoin was tested as an anaplerotic therapy for APBD, but the
    randomized crossover trial did not establish efficacy over six months
    despite acceptable safety.
  treatment_term:
    preferred_term: Pharmacotherapy
    term:
      id: NCIT:C15986
      label: Pharmacotherapy
  target_phenotypes:
  - preferred_term: Gait disturbance
    term:
      id: HP:0001288
      label: Gait disturbance
  evidence:
  - reference: PMID:29110179
    reference_title: A double-blind, placebo-controlled trial of triheptanoin in adult polyglucosan body disease and open-label, long-term outcome.
    supports: REFUTE
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      We cannot conclude that triheptanoin was effective in the treatment of
      APBD over a 6-month period, but we found it had a good safety profile.
    explanation: This refutes proven efficacy while documenting the completed treatment trial and safety signal.
clinical_trials:
- name: NCT00947960
  phase: PHASE_II
  status: COMPLETED
  description: >-
    Randomized controlled phase 2 study testing triheptanoin for APBD symptoms.
  target_phenotypes:
  - preferred_term: Gait disturbance
    term:
      id: HP:0001288
      label: Gait disturbance
  evidence:
  - reference: clinicaltrials:NCT00947960
    reference_title: A Treatment Trial of Triheptanoin in Patients With Adult Polyglucosan Body Disease - A Randomized Controlled Study
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: >-
      The purpose of the study is to determine if triheptanoin is an effective
      treatment for the symptoms of Adult Polyglucosan Body Disease.
    explanation: This identifies the APBD triheptanoin interventional trial.
datasets: []
references:
- reference: ORPHA:206583
  title: Adult polyglucosan body disease
  findings:
  - statement: >-
      APBD is an adult glycogen storage disease with progressive upper and lower
      motor neuron dysfunction, progressive neurogenic bladder, and cognitive
      difficulties that can lead to dementia.
    supporting_text: >-
      A glycogen storage disease of adults characterized by progressive upper
      and lower motor neuron dysfunction, progressive neurogenic bladder and
      cognitive difficulties that can lead to dementia.
- reference: PMID:20301758
  title: GBE1 Adult Polyglucosan Body Disease.
  tags:
  - GeneReviews
  findings:
  - statement: >-
      GeneReviews summarizes classic GBE1-APBD as adult-onset neurogenic
      bladder, gait difficulty from spasticity and weakness, distal sensory
      loss, autonomic dysfunction, and mild cognitive difficulty.
    supporting_text: >-
      Most individuals with classic GBE1 adult polyglucosan body disease
      (GBE1-APBD) present after age 40 years with unexplained progressive
      neurogenic bladder, gait difficulties (i.e., spasticity and weakness)
      from mixed upper and lower motor neuron involvement, sensory loss
      predominantly in the distal lower extremities, autonomic dysfunction
      (associated with orthostatic hypotension and constipation), and mild
      cognitive difficulties (often executive dysfunction).
- reference: DOI:10.1002/ana.23598
  title: "Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings"
  findings:
  - statement: >-
      Neurogenic bladder, spastic paraplegia with vibration loss, and axonal
      neuropathy were the most common clinical features in the natural-history
      cohort.
    supporting_text: >-
      The most common clinical findings were neurogenic bladder (100%), spastic
      paraplegia with vibration loss (90%), and axonal neuropathy (90%).
- reference: PMID:33141444
  title: "GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes."
  findings:
  - statement: >-
      APBD is caused by biallelic GBE1 pathogenic variants with deficient
      glycogen branching enzyme activity and polyglucosan storage across
      neuromuscular and nervous system tissues.
    supporting_text: >-
      Adult polyglucosan body disease (APBD) represents a complex autosomal
      recessive inherited neurometabolic disorder due to homozygous or compound
      heterozygous pathogenic variants in GBE1 gene, resulting in deficiency of
      glycogen-branching enzyme and secondary storage of glycogen in the form of
      polyglucosan bodies
- reference: PMID:36796138
  title: "Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource."
  findings:
  - statement: >-
      Expert clinical practice recommendations support diagnosis and
      multidisciplinary management for GSD IV phenotypes including APBD.
    supporting_text: >-
      The educational resource includes practical steps to confirm a GSD IV
      diagnosis and best practices for medical management
- reference: PMID:29110179
  title: A double-blind, placebo-controlled trial of triheptanoin in adult polyglucosan body disease and open-label, long-term outcome.
  findings:
  - statement: >-
      Triheptanoin was safe and tolerated but did not establish efficacy over a
      six-month randomized crossover treatment period.
    supporting_text: >-
      We cannot conclude that triheptanoin was effective in the treatment of
      APBD over a 6-month period, but we found it had a good safety profile.
📚

References & Deep Research

References

6
ORPHA:206583
Adult polyglucosan body disease
1 finding
APBD is an adult glycogen storage disease with progressive upper and lower motor neuron dysfunction, progressive neurogenic bladder, and cognitive difficulties that can lead to dementia.
"A glycogen storage disease of adults characterized by progressive upper and lower motor neuron dysfunction, progressive neurogenic bladder and cognitive difficulties that can lead to dementia."
PMID:20301758
GBE1 Adult Polyglucosan Body Disease.
1 finding
GeneReviews summarizes classic GBE1-APBD as adult-onset neurogenic bladder, gait difficulty from spasticity and weakness, distal sensory loss, autonomic dysfunction, and mild cognitive difficulty.
"Most individuals with classic GBE1 adult polyglucosan body disease (GBE1-APBD) present after age 40 years with unexplained progressive neurogenic bladder, gait difficulties (i.e., spasticity and weakness) from mixed upper and lower motor neuron involvement, sensory loss predominantly in the..."
DOI:10.1002/ana.23598
Adult polyglucosan body disease: Natural History and Key Magnetic Resonance Imaging Findings
1 finding
Neurogenic bladder, spastic paraplegia with vibration loss, and axonal neuropathy were the most common clinical features in the natural-history cohort.
"The most common clinical findings were neurogenic bladder (100%), spastic paraplegia with vibration loss (90%), and axonal neuropathy (90%)."
PMID:33141444
GBE1-related disorders: Adult polyglucosan body disease and its neuromuscular phenotypes.
1 finding
APBD is caused by biallelic GBE1 pathogenic variants with deficient glycogen branching enzyme activity and polyglucosan storage across neuromuscular and nervous system tissues.
"Adult polyglucosan body disease (APBD) represents a complex autosomal recessive inherited neurometabolic disorder due to homozygous or compound heterozygous pathogenic variants in GBE1 gene, resulting in deficiency of glycogen-branching enzyme and secondary storage of glycogen in the form of..."
PMID:36796138
Diagnosis and management of glycogen storage disease type IV, including adult polyglucosan body disease: A clinical practice resource.
1 finding
Expert clinical practice recommendations support diagnosis and multidisciplinary management for GSD IV phenotypes including APBD.
"The educational resource includes practical steps to confirm a GSD IV diagnosis and best practices for medical management"
PMID:29110179
A double-blind, placebo-controlled trial of triheptanoin in adult polyglucosan body disease and open-label, long-term outcome.
1 finding
Triheptanoin was safe and tolerated but did not establish efficacy over a six-month randomized crossover treatment period.
"We cannot conclude that triheptanoin was effective in the treatment of APBD over a 6-month period, but we found it had a good safety profile."

Deep Research

1
Adult Polyglucosan Body Disease Deep Research Fallback ▸

Adult Polyglucosan Body Disease Deep Research Fallback

Date: 2026-05-07

Provider Attempts

  • Falcon provider: timeout 120s just research-disorder falcon Adult_Polyglucosan_Body_Disease timed out with no usable artifact.
  • OpenAI provider: timeout 120s just research-disorder openai Adult_Polyglucosan_Body_Disease timed out with no usable artifact.

Evidence Scope Used For Curation

The YAML curation was completed from regenerated Orphanet cache and cached primary literature:

  • ORPHA:206583: Orphanet structured record for APBD definition, inheritance, GBE1 gene association, prevalence, and phenotype frequencies.
  • DOI:10.1002/ana.23598: 50-patient APBD natural history and MRI cohort supporting neurogenic bladder, spastic paraplegia, axonal neuropathy, cognitive decline, GBE1 mutation data, and characteristic brain/spine MRI findings.
  • PMID:33141444: GBE1-related disorders review supporting APBD inheritance, GBE1 causality, glycogen branching enzyme deficiency, polyglucosan body storage, and neuromuscular phenotypic spectrum.
  • PMID:36796138: clinical practice resource for diagnosis and management of GSD IV/APBD.
  • PMID:25665141: deep intronic GBE1 variant evidence supporting molecular genetic testing and GBE1 causality.
  • DOI:10.3389/fneur.2023.1261125: APBD proteomics study supporting secondary proteostasis and cellular stress pathway dysregulation.
  • PMID:29110179 and clinicaltrials:NCT00947960: triheptanoin randomized crossover trial and registry evidence, including lack of demonstrated efficacy over six months.