Evaluating and monitoring liver disease severity in glycogen storage disease type IX: Performance of novel and established clinical scores.

Purpose: Hepatic glycogen storage disease type IX (GSD IX) results from a deficiency of phosphorylase kinase. A noninvasive method of monitoring liver disease severity in this population is unavailable and liver biopsy remains the gold standard for classifying disease severity, particularly for liver fibrosis. Methods: We proposed 2 novel hepatic GSD IX-specific liver disease severity scoring systems: one that incorporated laboratory parameters ("novel lab-only score") and one that incorporated laboratory, abdominal imaging, and growth parameters ("novel comprehensive score"). We compared their performance with established scoring systems used for other liver diseases and liver biopsy to determine concordance. Results: Liver disease severity was assessed in 56 pediatric participants with hepatic GSD IX. The novel lab-only and comprehensive scores correctly differentiated between mild and severe liver disease in 72.4% and 66.7% of participants, respectively. The Pediatric Non-Alcoholic Fatty Liver Disease Fibrosis Score demonstrated the highest accuracy in liver disease severity classification, correctly differentiating between mild and severe liver disease in 82.4% of participants. Conclusion: Hepatic GSD IX requires longitudinal monitoring and liver disease severity prediction scores may be useful clinical tools to noninvasively grade the severity of liver disease. Liver biopsy remains an important part of clinical management to understand the extent of liver disease.