Potential use of other starch sources in the treatment of glycogen storage disease type Ia - an in vitro study.

BACKGROUND: Glycogen storage disease type Ia (GSD-Ia) is one of the most common hepatic GSD. Its treatment mainly consists of a diet including a high intake of slow-digestion carbohydrates such as raw cornstarch and the restriction of simple sugars. This enables the maintenance of euglycemia and prevents secondary metabolic disorders. Starch is a glucose polymer formed by amylose and amylopectin, which can be obtained from distinct sources. Although uncooked cornstarch has been successfully used in the treatment of GSD-Ia, it can lead to hyperglycemia and weight gain. in vitro andin vivo tests indicated that sweet manioc starch can be potentially used in the treatment of GSD-Ia. RESULTS: The moisture analysis revealed a variation from 10.3 to 12.8% in the sweet manioc starch samples, whereas the moisture content of uncooked cornstarch ranged from 7.3 to 11.1%. Quantifiable sugar was detected in 3/5 samples of sweet manioc starch and 1/3 samples of uncooked cornstarch. Notably, this uncooked cornstarch brand is widely employed in GSD-Ia treatment in Brazil. Products B and E had higher values of amylopectin and undetectable levels of sugars. A clinical trial is warranted to compare samples F and G and determine the impact of sugar trace in the same dietary source of starch. CONCLUSIONS: Collectively, the results demonstrated possible therapeutic alternatives for GSD-Ia in addition to traditional uncooked cornstarch.

Body composition in patients with hepatic glycogen storage diseases.

OBJECTIVES: The present study aimed to evaluate the body composition of hepatic glycogen storage disorders (GSDs) through dual energy x-ray absorptiometry. METHODS: This was an exploratory, observational, cross-sectional study. Twenty-four patients with GSD (type Ia: n = 13, Ib: n = 5, III: n = 2, and IX-α/ß/γ: n = 4; female sex: n = 13; age <8 y: n = 3, 8-19 y: n = 14, and >19 y: n = 7) were included. Three-day dietary records were collected in the week preceding dual energy x-ray absorptiometry. Body composition findings were correlated with clinical parameters, uncooked cornstarch (UCCS) regimen, dietary intake, and markers of treatment adherence. RESULTS: An elevated fat mass (FM) index was found in 16 of 21 patients (age 8-19 y: n = 10 and >19 y: n = 6; GSD type Ia: n = 12, Ib: n = 2, III: n = 1, and IX-γ: n = 1). A lean mass (LM) index evaluation showed no LM deficits in relation to corresponding reference populations. Relative skeletal muscle index values were decreased in 2 of 7 adult patients (type Ib: n = 1 and IX-α: n = 1). UCCS (g/d) correlated positively with the FM index (rs = 0.7; P ≤ 0.01). In contrast, relative UCCS intake (g/kg body weight) was negatively associated with LM/kg (rs = -0.8; P ≤ 0.01). CONCLUSIONS: These findings suggest a high frequency of elevated FM in patients with hepatic GSDs. We also suggest that treatment with UCCS is associated with excess weight in these patients. Additionally, the treatment strategy can impair protein intake, and lead to a decrease in LM.

Beyond predicting diagnosis: Is there a role for measuring biotinidase activity in liver glycogen storage diseases?

Introduction: Biotinidase synthesis is needed to recycle biotin for essential metabolic reactions. Biotinidase activity is lower than normal levels in advanced liver disease but is higher in hepatic glycogen storage disorders (GSDs), however the cause of this association remains unclear. Methods: In this study, biotinidase activity was measured in plasma samples from 45 individuals with hepatic GSDs; GSDI (a, b; n = 25) and GSD III (a, b; n = 20), complemented by a chart review to associate biotinidase activity levels with clinical laboratory and imaging findings known to be implicated in these GSDs. Results: Our findings showed variation in biotinidase activity levels among subjects with GSD I and III; biotinidase activity correlated positively with hypertriglyceridemia in subjects with GSD I (r = 0.47, P = 0.036) and GSD III (r = 0.58, P = 0.014), and correlated negatively with age (r = -0.50, P = 0.03) in patients with GSD III. Additionally, biotinidase activity was reduced, albeit within the normal range in subjects with evidence of fibrosis/cirrhosis, as compared to subjects with hepatomegaly with or without steatosis (P = 0.002). Discussions: These findings suggest that abnormal lipid metabolism in GSD I and III and progressive liver disease in GSD III may influence biotinidase activity levels. We suggest that a prospective, multi-center, longitudinal study designed to assess the significance of monitoring biotinidase activity in a larger cohort with hepatic GSDs is warranted to confirm this observation. Take-home message: Altered lipid metabolism and advancing liver fibrosis/cirrhosis may influence biotinidase activity levels in patients with hepatic glycogen storage disease. Thus, longitudinal monitoring of biotinidase activity, when combined with clinical and other biochemical findings may be informative.

A triple-blinded crossover study to evaluate the short-term safety of sweet manioc starch for the treatment of glycogen storage disease type Ia.

BACKGROUND: Glycogen storage disease type 1a (GSD Ia) is characterized by severe fasting hypoglycemia. The clinical management includes the administration of uncooked cornstarch (UCCS). Although such a diet approach is effective in achieving euglycemia, its impact on the quality of life of patients should be considered. In vitro analyses suggest a longer release of glucose when using sweet manioc starch (SMS). METHODS: We compared the efficacy and safety of the administration of SMS and UCCS during a short-fasting challenge in patients with GSD Ia in a randomized, triple-blind, phase I/II, cross-over study. GSD Ia patients aged ≥ 16 years and treated with UCCS were enrolled. Participants were hospitalized for two consecutive nights, receiving UCCS or SMS in each night. After the administration of the starches, glucose, lactate and insulin levels were measured in 1-h interval throughout the hospitalization period. The procedures were interrupted after 10 h of fasting or in a hypoglycemic episode (< 3.88 mmol/L). RESULTS: Eleven individuals (mean age: 21.6 ± 4.3 years; all presenting body mass index > 25 kg/m2) participated in the study. The average fasting period was 8.2 ± 2.0 h for SMS and 7.7 ± 2.3 h for UCCS (p = 0.04). SMS maintained euglycemia for a greater period over UCCS. Increased lactate concentrations were detected even in absence of hypoglycemia, not being influenced by the different starches investigated (p = 0.17). No significant difference was found in total cholesterol, HDL, triglycerides and uric acid levels in both arms. None of the patients showed severe adverse events. CONCLUSIONS: SMS appears to be non-inferior to UCCS in the maintenance of euglycemia, thus emerging as a promising alternative to the treatment of GSD Ia.