IMPORTANCE: Glycogen storage disease type Ib (GSDIb) is a rare metabolic disorder characterized by impaired glucose-6-phosphate transporter function with limited descriptions. OBJECTIVE: To describe the genetic and clinical features of Chinese patients with GSDIb. DESIGN, SETTING, AND PARTICIPANTS: This retrospective cohort study retrieved the medical records of 113 Chinese patients with GSDIb treated at a single institution in Shanghai from November 1, 2000, to June 30, 2024. MAIN OUTCOMES AND MEASURES: Biochemical parameters and clinical features (infections, inflammatory bowel disease [IBD], kidney and cardiovascular issues, growth and puberty) at baseline and the last follow-up, all-cause mortality, and mental and social development were assessed. RESULTS: A total of 113 patients (96 children [85%]
67 males [59%]) had GSDIb genetically diagnosed at a median age of 1.4 (range, 0.0-35.5) years. Thirty-eight novel SLC37A4 variants were identified. Hypoglycemia and metabolic derangements were the primary concerns in patients aged 2 years or younger (45%). Short stature (75%), infections (75%), and recurrent epistaxis (31%) became more prevalent in patients aged 2.1 to 5.0 years. The frequency of respiratory tract infection decreased after a median age of 7.0 (IQR, 3.5-10.5) years. Forty-four patients (46%) developed IBD at a median age of 6.0 (IQR, 3.0-12.0) years, 14% of whom developed IBD-associated arthritis at a median age of 10.5 (IQR, 5.8-19.6) years. The mean (SD) difference between the z scores of actual height and target height (Δ height z scores) at the final visit (-2.11 [1.76]) did not significantly increase even after uncooked cornstarch treatment. The mean (SD) Δ height z scores of the patients with IBD (-2.99 [1.70]) were significantly lower than those without IBD (mean [SD], -1.36 [1.44]) (P <
.001). Ten patients (9%) died due to complications of GSDIb, including metabolic derangements, sepsis, and/or severe pneumonia (n = 8), IBD (n = 1), and pulmonary hypertension (n = 1). CONCLUSIONS AND RELEVANCE: In this cohort study, the genetic and clinical spectra of GSDIb were broadened, suggesting associations between GSDIb and bowel, growth, and survival outcomes. To date, no previous study reported IBD-associated arthritis.