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



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.


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.


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).


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.





Published Version (Please cite this version)


Publication Info

El-Gharbawy, Areeg, Adviye A Tolun, Carine A Halaby, Stephanie L Austin, Priya S Kishnani and Deeksha S Bali (2022). Beyond predicting diagnosis: Is there a role for measuring biotinidase activity in liver glycogen storage diseases?. Molecular genetics and metabolism reports, 31. p. 100856. 10.1016/j.ymgmr.2022.100856 Retrieved from

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Areeg Hassan El-Gharbawy

Associate Professor of Pediatrics

I am an Associate Professor in the Department of Pediatrics, Division of Medical Genetics at Duke University; pursuing a career in clinical/translational research with 70% protected time for research. My clinical background is broad encompassing residency and fellowship training in internal medicine, endocrinology, diabetes, nutrition, metabolism, and clinical and biochemical genetics. This uniquely positioned me to evaluate and study pediatric and adult patients with inborn errors of metabolism, mitochondrial disorders, and lysosomal storage diseases. I transitioned from clinical medicine to a career in translational research to address the needs of patients with rare inherited metabolic disorders due to the paucity of therapies and biomarkers. My strength comes from my experience in managing patients with different inborn errors of metabolism and optimizing their treatment based on their underlying clinical, molecular, and biochemical phenotypes. In the era of precision medicine and big data analysis, my aim is to utilize my clinical skills and available tools at Duke University to conduct studies with implications for new drug, mechanism, and biomarker discovery. Studies are and will be conducted at Duke clinical research center in collaboration with clinical and basic scientists including Priya Kishnani, MD, Dwight Koeberl MD, Ph.D., and Karl-Dimiter Bissig MD, Ph.D. who are well established and funded clinical and basic science investigators at Duke. This collaboration allows me to integrate clinical data generated from natural history studies, with result from animal models, and metabolomics. This has implications for discovering innovative therapies, mechanisms, and biomarkers that serve and optimize patient care. I am currently analyzing metabolomics data on patients with Glycogen storage diseases and new therapeutics. I hold an IND on a PI initiated (industry-funded) clinical trial (pilot study) for using triheptanoin an anaplerotic compound that promotes energy through the Krebs cycle in patients with glycogen storage disease type 1.


Priya Sunil Kishnani

Chen Family Distinguished Professor of Pediatrics


A multidisciplinary approach to care of individuals with genetic disorders in conjunction with clinical and bench research that contributes to:
1) An understanding of the natural history and delineation of long term complications of genetic disorders  with a special focus on liver Glycogen storage disorders, lysosomal disorders with a special focus on Pompe disease, Down syndrome and hypophosphatasia
2) ) The development of new therapies such as AAV gene therapy, enzyme therapy, small molecule and other approaches for genetic disorders through translational research

3) The development and execution of large multicenter trials to confirm safety and efficacy of potential therapies
4) Role of antibodies/immune response in patients on therapeutic proteins and AAV gene therapy

. Glycogen Storage Disease (GSD): We are actively following subjects with all types of Glycogen Storage Disease, with particular emphasis on types I, II, III, IV, VI and IX. The goal of the treatment team is to better determine the clinical phenotype and long term complications of these diseases. Attention to disease manifestations observed in adulthood, such as adenomas and risk for HCC, is of paramount importance in monitoring and treating these chronic illnesses. We are establishing clinical algorithms for managing adenomas, and the overall management of these patients including cardiac, bone, muscle and liver issues. A special focus is biomarker discovery, an Omics approach including metabolomics and immune phenotyping. We are working on AAV gene therapy for several hepatic GSDs

.Lysosomal Storage Disease: The Duke Lysosomal Storage Disease (LSD) treatment center follows and treats patients with Pompe, Gaucher, Fabry, Mucopolysaccharidosis, Niemann Pick, LAL-D and other LSD's. The Duke Metabolism Clinical Research Team is exploring many aspects of enzyme replacement therapy (ERT), including impact on different systems, differential response, and long term effects. Other symptomatic and treatment interventions for this category of diseases are also being explored in the context of clinical care.

. Pompe Disease: The care team has extensive experience in the care of infants and adults with Pompe disease and was instrumental in conducting clinical trials and the bench to bedside work that led to the 2006 FDA approval of alglucosidase alfa, the first treatment for this devastating disease. We are currently focusing on role of antibodies/immune response on patient outcome and role of immune modulation/immune suppression as an adjunct to ERT. Our team is also working on AAV gene therapy for Pompe disease. A focus is on newborn screening (NBS) and understanding the clinical phenotype and management approaches for babies identified via NBS

.  Hypophosphatasia: We follow a large cohort of patients with HPP. The goal is to understand the features of the disease beyond bone disease, development of biomarkers, role of ERT and immune responses in HPP

. Neuromuscular disorders: We are collaborating with neurologists, cardiologists and neuromuscular physicians to serve as a treatment site for clinical trials in these diseases. We are currently involved in trials of DMD and are working closely on setting up collaborations for studies in SMA.


Deeksha Sarihyan Bali

Professor of Pediatrics

1)Development of new non-invasive laboratory diagnostic methods using enzymology and molecular diagnostic techniques for Glycogen Storage Diseases (GSDs) and Lysosomal Storage Diseases (LSDs) like Pompe, Fabry, Gaucher, MPS - for early diagnosis and treatment modalities. Exploration of new high throughput diagnostic platforms with an idea of implementation into New born screening (NBS)of these diseases.

2)Clinical research studies associated with Pompe disease with a goal to improve the diagnosis, current therapies and patient care, with special emphasis on clinical development of Cross Reactive Immunologic Material (CRIM) diagnostic methods and association with underlying pathogenic GAA mutations and clinical correlations.

3) Clinical research studies involving other common LSDs (Fabry, MPSI,II,IVa and VI, Gaucher, Wolman disease and more) focusing on early diagnosis and new born screening.

4)Understanding the hepatocellular adenoma (HCA) and hepatocellular carcinomas (HCC) transformation in GSD I, using paired samples from resected adenomas and adjoining liver tissue. Experiments use SNP and expression microarray analysis, miRNA and CNV analysis in collaboration with other investigators.

5)Pursuing genotype-phenotype correlations for various clinical phenotypes of GSD IX, in order to better understand clinical heterogeneity. Severe phenotypes of GSD IX resulting in liver cirrhosis and Cardiac involvement are of special interest to us, especially their association with the underlying pathogenic mutations.

6)Research on Pompe/Mannose-6-phosphate receptor (M6PR300) double knock out mice to understand the role of M6PR in rhGAA uptake and glycogen clearance and also beta-agonist like Clenbuterol.

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