RESUMEN
Background: Glycogen storage disease type Ib (GSD Ib) is an autosomal recessively inherited deficiency of the glucose-6-phosphate translocase (G6PT). Clinical features include a combination of a metabolic phenotype (fasting hypoglycemia, lactic acidosis, hepatomegaly) and a hematologic phenotype with neutropenia and neutrophil dysfunction. Dietary treatment involves provision of starches such as uncooked cornstarch (UCCS) and Glycosade® to provide prolonged enteral supply of glucose. Granulocyte colony-stimulating factor (G-CSF) is the treatment of choice for neutropenia. Because long-term stimulation of hematopoiesis with G-CSF causes serious complications such as splenomegaly, hypersplenism, and osteopenia; hematopoietic stem cell transplantation (HSCT) has been considered in some patients with GSD Ib to correct neutropenia and avoid G-CSF related adverse effects. Whether HSCT also has an effect on the metabolic phenotype and utilization of carbohydrate sources has not been determined. Objective: Our objective was to measure the utilization of starch in a patient with GSD Ib before and after HSCT using the minimally invasive 13C-glucose breath test (13C-GBT). Design: A case of GSD Ib (18y; female) underwent 13C-GBT four times: UCCS (pre-HSCT), UCCS (3, 5 months post-HSCT) and Glycosade® (6 months post-HSCT) with a dose of 80 g administered via nasogastric tube after a 4 h fast according to our patient's fasting tolerance. Breath samples were collected at baseline and every 30 min for 240 min. Rate of CO2 production was measured at 120 min using indirect calorimetry. Finger-prick blood glucose was measured using a glucometer hourly to test hypoglycemia (glucose <4 mmol/L). Biochemical and clinical data were obtained from the medical records as a post-hoc chart review. Results: UCCS utilization was significantly higher in GSD Ib pre-HSCT, which reduced and stabilized 5 months post-HSCT. UCCS and Glycosade® utilizations were low and not different at 5 and 6 months post-HSCT. Blood glucose concentrations were not significantly different at any time point. Conclusions: Findings show that HSCT stabilized UCCS utilization, as reflected by lower and stable glucose oxidation. The results also illustrate the application of 13C-GBT to examine glucose metabolism in response to various carbohydrate sources after other treatment modalities like HSCT in GSD Ib.
RESUMEN
Glycogenosis type Ib (GSD1B) causes not only hypoglycemia but also infections and "Crohn's disease like" inflammatory bowel disease (IBD) that can significantly impair patient's quality of life. We retrospectively evaluated infectious and digestive complications in 9 French patients (3 girls, 6 boys) diagnosed at 0.8 years on average, with a mean follow-up of 19.1 years. Infections occurred earlier than IBD, at mean ages of 1.7 and 3.8 years, respectively. The number of acute hospitalizations was 0.7/year due to infectious (0.4/year) or digestive symptoms (0.4/year). Clinical presentations allowed separating patients into mild (n = 5) and severe (n = 4) intestinal involvement. Patients in the severe group had more serious digestive symptoms but also earlier neutropenia (median 0.3 vs. 1.5 years, p =0 .046) with a tendency to a lower neutrophil count (NC) during follow-up, and a higher number of acute hospitalizations (median 1.3/year vs. 0.2/year, p =0 .014) due to digestive symptoms (median 0.6/year vs. 0.05/year, p = 0,012) and infections (median 0.8/year vs. 0.2/year, p =0 .014). Treatments included G-CSF and cotrimoxazole (n = 7), 5-aminosalicylic acid (n = 2), and a polymeric solution enriched in the anti-inflammatory cytokine TGF-ß (n = 4, "severe" group), and immunomodulatory treatment (n = 1). In conclusion, infections and IBD are rare but severe complications in GSD1B. Neutropenia tended to be more prevalent in the severe IBD group than in the mild IBD group. Dietetic treatment with specific anti-inflammatory solutions seems particularly appropriate in these patients.