Rare Glycogen Storage Diseases Natural History Study

Inclusion Criteria: * Diagnosis of a rare GSD, including 0a, 0b, VII, X, XII, XIII, XV, PRKAG2 syndrome or Danon disease * Two variants in the gene associated with the specific GSD type (for autosomal recessive diseases) * One variant in the gene associated with the specific GSD type (for autosomal dominant or X-linked diseases) * Deficient enzyme activity in liver, muscle, skin fibroblast or other tissue * One variant in causative gene with evidence of disease, per a clinician * Histology as confirmed by a 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 a rare GSD will be included Exclusion Criteria: * Unable to provide informed consent for participation for one's self or by legally authorized representative/legal guardian/parent