A Phase 1/2, Dose-Exploration Study to Evaluate the Safety and Efficacy of BEAM-301 in Patients With Glycogen Storage Disease Type Ia (GSDIa)

Inclusion Criteria: 1. Males or females age ≥18 years of age at the time of consent. 2. Diagnosis of GSDIa and homozygous or compound heterozygous for the G6PC1 c.247C\>T (p.R83C) variant (confirmed by genetic testing). 3. History of at least 1 episode of hypoglycemia \<60 mg/dL within the 2 years prior to signing the ICF. Exclusion Criteria: 1. Liver transplant recipient/on waiting list for liver transplant or known history of liver cirrhosis. 2. Presence of liver adenoma \>5 cm in size based on liver MRI or liver ultrasound performed at screening or within 6 months prior to screening. 3. Presence of liver adenoma \>3 cm and ≤5 cm with a documented annual growth rate of ≥0.5 cm per year. 4. Have aspartate transaminase or alanine transaminase \>upper limit of normal (ULN). 5. Total bilirubin levels \>ULN; if documented Gilbert's Syndrome, total bilirubin \>2 × ULN. 6. Previous treatment with any cell-, gene-, or viral vector-derived therapy Hospitalization for management of hypoglycemia within 4 weeks prior to signing the ICF. 7. Have triglycerides \>1000 mg/dL or a history of pancreatitis or a history of acute pancreatitis within 5 years that does not have a known and corrected etiology (eg, cholecystectomy for gallstone pancreatitis).