Our team at the Congenital Hyperinsulinism Center at CHOP is working on a research study to determine whether an experimental gene therapy product, DTX401, is safe and effective in people with glycogen storage disease type Ia (GSDIa). The FDA has not approved this drug for the treatment of GSDIa but has approved us to use this drug as part of this clinical trial. The purpose of this research study is to see if DTX401 can help people with GSDIa have normal blood sugar levels and fewer episodes of hypoglycemia. DTX041 works by delivering copies of the G6PC gene to your liver through a one-time infusion. Participation in this study will last for 2 years and will involve 30 study visits. It is possible that treatment with the study drug infusion may improve your blood sugar levels. Travel costs will be covered by the study and you will receive compensation for participating.