Abstract
Background Glycogen storage disease type IV (GSD IV) is an ultrarare autosomal recessive disorder that causes deficiency of functional glycogen branching enzyme and formation of abnormally structured glycogen termed polyglucosan. GSD IV has traditionally been categorized based on primary hepatic or neuromuscular involvement, with hepatic GSD IV subclassified as discrete subtypes: classic (progressive) and nonprogressive.Methods To better understand the progression of liver disease in GSD IV, we present clinical and histopathology data from 23 patients from around the world and characterized the liver involvement in the Gbe1ys/ys knockin mouse model.Results We propose an alternative to the established subtype-based terminology for characterizing liver disease in GSD IV and recognize 3 tiers of disease severity: (i) “severe progressive” liver disease, (ii) “intermediate progressive” liver disease, and (iii) “attenuated” liver disease. Analysis of liver pathology revealed that risk for liver failure cannot be predicted from liver biopsy findings alone in individuals affected by GSD IV. Moreover, analysis of postmortem liver pathology from an individual who died over 40 years after being diagnosed with nonprogressive hepatic GSD IV in childhood verified that liver fibrosis did not regress. Last, characterization of the liver involvement in a mouse model known to recapitulate the adult-onset neurodegenerative form of GSD IV (Gbe1ys/ys mouse model) demonstrated hepatic disease.Conclusion Our findings challenge the established subtype-based view of GSD IV and suggest that liver disease severity among patients with GSD IV represents a disease continuum.Trial registration ClinicalTrials.gov NCT02683512Funding None
Authors
Rebecca L. Koch, Bridget T. Kiely, Su Jin Choi, William R. Jeck, Leticia S. Flores, Vikrant Sood, Seema Alam, Gilda Porta, Katy LaVecchio, Claudia Soler-Alfonso, Priya S. Kishnani
Figure 2
Evaluation of extent of liver fibrosis by elastography, biopsy, and conventional imaging studies in patients with hepatic GSD IV.
