GBE Deficiency (GSD IV and APBD) Natural History Study
Collection and review of clinical information related to glycogen branching enzyme (GBE) deficiency, diagnosed as Glycogen Storage Disease Type IV (GSD IV) or Adult Polyglucosan Body Disease (APBD generated during clinic visits.
‣ Diagnosis of GSD IV or APBD via:
⁃ Two variants in the GBE1 gene
• Deficient GBE activity in liver, muscle, skin fibroblast or other tissue
• One variant in GBE1 gene with evidence of disease that is pathogenic, per the clinician
‣ Able to provide informed consent for self (adults) or affected individual (minor or adults with a legally authorized representative)
‣ Able to provide consent for release of medical records
‣ Pregnant women with a diagnosis of GSD IV or APBD will be included
‣ Histology as confirmed by clinician