GSD VI and GSD IX Natural History

This natural history study will serve as a repository of clinical, laboratory, and biochemical information on individuals with GSD VI or GSD IX. This information will allow a more definitive description of glycogen phosphorylase (GP) and phosphorylase kinase (PhK) deficiency to be developed, which will permit development of treatment strategies for these diseases.

Duke will be the only site where this study takes place. However, since these are rare disorders, participants who receive care at other institutions will be included. The investigators will collect retrospective data from patient charts on diagnosed individuals, as far back as necessary to capture the clinical course of the disorder. Prospective data collected from patient charts after enrollment will be captured as well. Participant's medical records will be continually reviewed for the duration of the study.

Data will be collected from medical records and will only pertain to clinically relevant information, including, but not limited to: demographic and diagnostic information, tissue biopsy results, medical and family history, review of systems, imaging studies, results of liver and/or muscle testing, and urine and blood laboratory results.

Inclusion criteria

• Diagnosis of GSD VI or GSD IX via:

• Two variants in the PYGL, PHKA1, PHKA2, PHKG1, PHKG2, or PHKB gene (or one variant with evidence of disease). Note: for males, one variant in the PHKA1 or PHKA2 gene is sufficient for inclusion.
• Deficient GP activity or PhK activity per enzymology
• Histology as confirmed by clinician
• Pregnant women with a diagnosis of GSD VI or GSD IX will be included
• 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

Exclusion criteria

• Unable to provide informed consent for participation for one's self or by legally authorized representative/legal guardian/parent