GSD VI and GSD IX Natural History

Collection and review of clinical information related to Glycogen Storage Disease Type VI (GSD VI) OR Glycogen Storage Disease Type IX (GSD IX) generated during clinic visits.

Study Overview

• Status: Recruiting
• Conditions: Glycogen Storage Disease VI; GLYCOGEN STORAGE DISEASE IXa1; GLYCOGEN STORAGE DISEASE IXa2; Glycogen Storage Disease IXB; Glycogen Storage Disease IXC; GSD 9 (All Subtypes); GSD 6
• Intervention / Treatment: Other: No intervention

Detailed Description

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.

• Study Type: Observational
• Enrollment (Estimated): 400

Contacts and Locations

• Study Contact: Name: Rebecca L Koch, PhD, RDN; Phone Number: 919-681-8823; Email: rebecca.koch@duke.edu
• Study Contact Backup: Name: Nisha Dalal, M.S. CCC-SLP; Phone Number: 919-668-3107; Email: nisha.dalal@duke.edu

Study Locations

• United States
  • North Carolina
    • Durham, North Carolina, United States, 27710
      • Recruiting
      • Duke University
      • Contact: Rebecca L Koch, PhD, RDN; Phone Number: 919-681-8823; Email: rebecca.koch@duke.edu
      • Contact: Nisha Dalal, M.S. CCC-SLP; Phone Number: 919-668-3107; Email: nisha.dalal@duke.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 1 second to 90 years (Child, Adult, Older Adult)
• Accepts Healthy Volunteers: No

• Sampling Method: Non-Probability Sample

Study Population

All patients with GSD VI or GSD IX, regardless of gender or ethnicity, are eligible for enrollment.

Description

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

Study Plan

How is the study designed?

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Time Frame
Progression of disease confirmed by medical record review	through study completion, an average of 10 years
Serum biotinidase activity	through study completion, an average of 10 years
Number of genotypes presented	through study completion, an average of 10 years
Number of phenotypes presented	through study completion, an average of 10 years

Collaborators and Investigators

• Sponsor: Duke University
• Collaborators: Kriya Therapeutics
• Investigators: Principal Investigator: Priya Kishnani, MD, Duke University

Publications and helpful links

General Publications

• Koch RL, Fares AH, Cocanougher BT, Lim J, Haijer-Schreuder AB, Derks TGJ, Grunert SC, Sharma R, Jones KA, Kishnani PS. PHKA1-associated phosphorylase kinase deficiency: a monogenic disorder of exercise intolerance and myalgia. NPJ Genom Med. 2025 Nov 10;10(1):71. doi: 10.1038/s41525-025-00527-y.

Study record dates

Study Major Dates

• Study Start (Actual): September 18, 2020
• Primary Completion (Estimated): January 1, 2030
• Study Completion (Estimated): January 1, 2030

Study Registration Dates

• First Submitted: June 29, 2020
• First Submitted That Met QC Criteria: June 29, 2020
• First Posted (Actual): July 1, 2020

Study Record Updates

• Last Update Posted (Actual): May 5, 2026
• Last Update Submitted That Met QC Criteria: May 4, 2026
• Last Verified: May 1, 2026

More Information

Terms related to this study

• Additional Relevant MeSH Terms: Metabolism, Inborn Errors; Genetic Diseases, Inborn; Metabolic Diseases; Carbohydrate Metabolism, Inborn Errors; Glycogen Storage Disease; Congenital, Hereditary, and Neonatal Diseases and Abnormalities; Nutritional and Metabolic Diseases; Glycogen Storage Disease Type VI; Glycogen Storage Disease, Type IXA2; Glycogen Storage Disease IXB; Glycogen Storage Disease IXC
• Other Study ID Numbers: Pro00104116

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: NO

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No