In vivo characterization of glycogen storage disease type III in a mouse model using glycoNOE MRI.

PURPOSE: Glycogen storage disease type III (GSD III) is a rare inherited metabolic disease characterized by excessive accumulation of glycogen in liver, skeletal muscle, and heart. Currently, there are no widely available noninvasive methods to assess tissue glycogen levels and disease load. Here, we use glycogen nuclear Overhauser effect (glycoNOE) MRI to quantify hepatic glycogen levels in a mouse model of GSD III. METHODS: Agl knockout mice (n = 13) and wild-type controls (n = 10) were scanned for liver glycogen content using glycoNOE MRI. All mice were fasted for 12 to 16 h before MRI scans. GlycoNOE signal was quantified by fitting the Z-spectrum using a four-pool Voigt lineshape model. Next, the fitted direct water saturation pool was removed and glycoNOE signal was estimated from the integral of the residual Z spectrum within -0.6 to -1.4 ppm. Glycogen concentration was also measured ex vivo using a biochemical assay. RESULTS: GlycoNOE MRI clearly distinguished Agl knockout mice from wild-type controls, showing a statistically significant difference in glycoNOE signals in the livers across genotypes. There was a linear correlation between glycoNOE signal and glycogen concentration determined by the biochemical assay. The obtained glycoNOE maps of mouse livers also showed higher glycogen levels in Agl knockout mice compared to wild-type mice. CONCLUSION: GlycoNOE MRI was used successfully as a noninvasive method to detect liver glycogen levels in mice, suggesting the potential of this method to be applied to assess glycogen storage diseases.

Physical therapy assessment and whole-body magnetic resonance imaging findings in children with glycogen storage disease type IIIa: A clinical study and review of the literature.

INTRODUCTION: Early recognized manifestations of GSD III include hypoglycemia, hepatomegaly, and elevated liver enzymes. Motor symptoms such as fatigue, muscle weakness, functional impairments, and muscle wasting are typically reported in the 3rd to 4th decade of life. OBJECTIVE: In this study, we investigated the early musculoskeletal findings in children with GSD IIIa, compared to a cohort of adults with GSD IIIa. METHODS: We utilized a comprehensive number of physical therapy outcome measures to cross-sectionally assess strength and gross motor function including the modified Medical Research Council (mMRC) scale, grip and lateral/key pinch, Gross Motor Function Measure (GMFM), Gait, Stairs, Gowers, Chair (GSGC) test, 6 Minute Walk Test (6MWT), and Bruininks-Oseretsky Test of Motor Proficiency Ed. 2 (BOT-2). We also assessed laboratory biomarkers (AST, ALT, CK and urine Glc4) and conducted whole-body magnetic resonance imaging (WBMRI) to evaluate for proton density fat fraction (PDFF) in children with GSD IIIa. Nerve Conduction Studies and Electromyography results were analyzed where available and a thorough literature review was conducted. RESULTS: There were a total of 22 individuals with GSD IIIa evaluated in our study, 17 pediatric patients and 5 adult patients. These pediatric patients demonstrated weakness on manual muscle testing, decreased grip and lateral/key pinch strength, and decreased functional ability compared to non-disease peers on the GMFM, 6MWT, BOT-2, and GSGC. Additionally, all laboratory biomarkers analyzed and PDFF obtained from WBMRI were increased in comparison to non-diseased peers. In comparison to the pediatric cohort, adults demonstrated worse overall performance on functional assessments demonstrating the expected progression of disease phenotype with age. CONCLUSION: These results demonstrate the presence of early musculoskeletal involvement in children with GSD IIIa, most evident on physical therapy assessments, in addition to the more commonly reported hepatic symptoms. Muscular weakness in both children and adults was most significant in proximal and trunk musculature, and intrinsic musculature of the hands. These findings indicate the importance of early assessment of patients with GSD IIIa for detection of muscular weakness and development of treatment approaches that target both the liver and muscle.

Whole-Body Muscle Magnetic Resonance Imaging in Glycogen-Storage Disease Type III.

INTRODUCTION: The main objective of this study was to describe muscle involvement on whole-body magnetic resonance imaging scans in adults at different stages of glycogen-storage disease type III (GSDIII). METHODS: Fifteen patients, 16-59 years of age, were examined on a 3-T system. The examinations consisted of coronal and axial T1-weighted images or fat images with a Dixon technique, and were scored for 47 muscles using Mercuri's classification. Muscle changes consisted of internal bright signals of fatty replacement. RESULTS: Distribution across muscles showed predominant signal alteration in the lower limbs and postural muscles. This finding is consistent with the overall clinical presentation of GSDIII and the results of heatmap scores. Review of the MRI scans provided new information regarding recurrent muscle changes, particularly in the soleus, gastrocnemius medial head, and thoracic extensor muscles. DISCUSSION: Whole-body muscle imaging provides clinically relevant information regarding muscle involvement in GSDIII. A severity score may contribute to improved patient management. Muscle Nerve, 2019.

Muscle Ultrasound in Patients with Glycogen Storage Disease Types I and III.

In glycogen storage diseases (GSDs), improved longevity has resulted in the need for neuromuscular surveillance. In 12 children and 14 adults with the "hepatic" (GSD-I) and "myopathic" (GSD-III) phenotypes, we cross-sectionally assessed muscle ultrasound density (MUD) and muscle force. Children with both "hepatic" and "myopathic" GSD phenotypes had elevated MUD values (MUD Z-scores: GSD-I > 2.5 SD vs. GSD-III > 1 SD, p < 0.05) and muscle weakness (GSD-I muscle force; p < 0.05) of myopathic distribution. In "hepatic" GSD-I adults, MUD stabilized (GSD-I adults vs. GSD-I children, not significant), concurring with moderate muscle weakness (GSD-I adults vs. healthy matched pairs, p < 0.05). In "myopathic" GSD-III adults, MUD increased with age (MUD-GSD III vs. age: r = 0.71-0.83, GSD-III adults > GSD-III children, p < 0.05), concurring with pronounced muscle weakness (GSD-III adults vs. GSD-I adults, p < 0.05) of myopathic distribution. Children with "hepatic" and "myopathic" GSD phenotypes were both found to have myopathy. Myopathy stabilizes in "hepatic" GSD-I adults, whereas it progresses in "myopathic" GSD-III adults. Muscle ultrasonography provides an excellent, non-invasive tool for neuromuscular surveillance per GSD phenotype.

Echocardiographic manifestations of Glycogen Storage Disease III: increase in wall thickness and left ventricular mass over time.

PURPOSE: Glycogen Storage Disease Type III, glycogen debranching enzyme deficiency, causes accumulation of glycogen in liver, skeletal, and cardiac muscle. Some patients develop increased left ventricular thickness by echocardiography, but the rate of increase and its significance remain unclear. METHODS: We evaluated 33 patients with Glycogen Storage Disease Type III, 23 with IIIa and 10 with IIIb, ages 1 month to 55.5 years, by echocardiography for wall thickness, left ventricular mass, shortening and ejection fractions, at 1 time point (n = 33) and at 2 time points in patients with more than 1 echocardiogram (13 of the 33). RESULTS: Of 23 cross-sectional patients with type IIIa, 12 had elevated left ventricular mass, 11 had elevated wall thickness. One type IIIb patient had elevated left ventricular mass but four had elevated wall thickness. For those with multiple observations, 9 of 10 with type IIIa developed increased left ventricular mass over time, with three already increased at first measurement. Shortening and ejection fractions were generally normal. CONCLUSION: Elevated left ventricular mass and wall thickness is more common in patients with type IIIa but develops rarely in type IIIb, although ventricular systolic function is preserved. This suggests serial echocardiograms with attention to left ventricular thickness and mass are important for care of these patients.

Bone mineral density and markers of bone turnover in patients with glycogen storage disease types I, III and IX.

Patients with glycogen storage disease (GSD) types I, III and IX show reduced bone mineral content, but there is scarce data on new serum and urine markers of bone turnover or their relationship to bone densitometry. Six GSD I, four GSD III and four GSD IX patients underwent bone mineral density (BMD) measurement by dual-energy X-ray absorptiometry. Free pyridinoline (fPYD):creatinine and free deoxypyridinoline (fDPD):creatinine ratios were analysed on random urines. Procollagen type I C-terminal propeptide, procollagen type I N-terminal propeptide (PINP), carboxyterminal telopeptide of type I collagen and bone-specific alkaline phosphatase were analysed in serum. Some GSD I and GSD III patients had low or very low BMD. There was no difference in total body BMD z-score between the GSD types after adjusting for height (p=0.110). Bone marker analysis showed no consistent pattern. Urine fPYD:creatinine ratio was raised in four GSD I and two GSD III patients, while serum PINP was inappropriately low in some of these patients. There was no clear correlation between any markers of bone destruction and total body z-score, but the patient with the lowest total body z-score showed the highest concentrations of both urinary fPYD:creatinine and fDPD:creatinine ratios. We conclude that some GSD I and GSD III patients have very low bone mineral density. There is no correlation between mineral density and bone markers in GSD patients. The inappropriately low concentration of PINP in association with the raised urinary fPYD:creatinine and fDPD:creatinine ratios seen in two GSD I patients reflect uncoupling of bone turnover. All these findings taken together suggest that some GSD I and GSD III patients may be at an increased risk of osteoporosis.

The prevalence of polycystic ovaries in the hepatic glycogen storage diseases: its association with hyperinsulinism.

OBJECTIVE: There has been much debate concerning the relative contribution of insulin resistance to the development of polycystic ovaries (PCO). We therefore aimed to assess ovarian morphology and insulin/androgen status in females with the hepatic glycogen storage diseases types Ia (GSD-Ia) and III (GSD-III), disorders associated with abnormalities of insulin secretion. DESIGN: A cross-sectional study of ovarian ultrasonography, oral glucose tolerance tests (oGTTs) and single measurements of gonadotrophins and androgens were performed. PATIENTS: Twenty-seven patients were evaluated: 13 with GSD-Ia, median age 11.2 years (range, 3.3-26.7) and 14 with GSD-III, aged 13.2 years (4.2-31.3). None had clinical signs of hyperandrogenism and only two of the 13 adults (15%) had menstrual irregularities. They were compared to 9 normal adult female controls, aged 21-28 years. MEASUREMENTS: Ovarian morphology and volume were measured. Blood glucose and plasma insulin concentrations were measured at the beginning and end of a 2-hour oGTT. Single measures of LH, FSH, testosterone, dehydroepiandrosterone sulphate, androstenedione, IGF-I and SHBG were made on samples taken at the beginning of the oGTT. RESULTS: In both GSD-Ia and III, all those older than 4.8 years of age had a polycystic ovarian appearance. Pre-pubertal GSD-Ia patients had lower basal and 2-hour blood glucose and plasma insulin concentrations than pre-pubertal GSD-III patients. In adults with GSD-Ia and GSD-III, although basal and 2-hour blood glucose concentrations did not differ, both basal and 2-hour plasma insulin concentrations were significantly higher than controls. Serum gonadotrophins, androgens, IGF-I and SHBG were mostly normal. CONCLUSIONS: A polycystic ovarian appearance is a common finding in patients with glycogen storage disease even before puberty. In GSD-III and adults with GSD-Ia, this ovarian appearance was associated with hyperinsulinism, suggesting an aetiological link, but this was not the case in pre-pubertal children with GDS-Ia. Inborn errors of carbohydrate metabolism may act as useful models for examining control mechanisms of ovarian physiology and development.

Hepatic ultrasound findings in the glycogen storage diseases.

Hepatic ultrasonography was performed on 70 patients with the hepatic glycogen storage diseases (GSDs) to assess parenchymal echogenicity. 27 patients had GSD-I, 24 had GSD-III and 19 had GSDs-VI/IX; ages varied from 0.6 to 35.7 years (median 11.7). 31 (44%) had normal or mild parenchymal changes, and 41% (11/27) of those with GSD-I, 25% (6/24) with GSD-III and 11% (2/19) with GSDs-VI/IX had marked changes. No relationships were found between the ultrasonographic appearances and other indices of metabolic control, including plasma triglycerides, total cholesterol or height standard deviation score. Seven adult patients (21-29 years) were found to have hepatic tumours: six with GSD-I and one with GSD-III. Those with GSD-I and tumours tended to have the more severe hepatic parenchymal changes. We conclude that ultrasonography may be useful in identifying patients with GSD-I at risk of hepatic tumour formation.

Liver-spleen scintigraphy in glycogen storage disease (glycogenoses).

Some forms of glycogen storage disease (GSD) primarily affect the liver, including types I, III, IV, VI, IX and 0. Scanning with Tc-99m sulfur colloid, while not being specific, does reveal some characteristic features. Most experience is with scanning in type I disease, though there are few reports in the literature. Six patients with type I, type III, type IV, and probably type VI disease are presented in this report. GSD should be considered in infants and young children presenting with hepatomegaly and abnormal liver-spleen scans. Sequential imaging is useful in following these patients. When focal defects are present, long term follow-up is indicated to detect hepatocellular adenocarcinoma.

Radiography of glycogen storage diseases.

Sixty-three patients with glycogen storage disease were evaluated. Findings on plain film examinations, excretory urography, barium gastrointestinal studies, ultrasonography, and angiography were categorized by type of glycogen storage disease. In type I findings include hepatomegaly with hepatic dysfunction, renomegaly with an increased incidence of renal calculi, and osteopenia with various associated osseous abnormalities. These changes were less pronounced in types III, IV, and VI. Type II displayed either cardiac or skeletal muscle glycogen deposition. Correlation with postmortem examination in 14 individuals is given.