Late-Onset Pompe Disease Presenting as Acute Hypercapnic Respiratory Failure in an Adolescent Male: A Diagnostic Challenge

Background: Late-onset Pompe disease (LOP) is a rare inherited disorder also known as acid alpha-glucosidase deficiency (GAA deficiency) in which the acid alpha-glucosidase enzyme is either not made or does not work properly, causing a gradual build-up of glycogen in the muscles of the body, including those in the skeletal and respiratory systems. Proximal muscle weakness and respiratory insufficiency are common symptoms that are often misdiagnosed because the disease slowly progresses over several months. Case Presentation: We here describe the case of a juvenile patient (age 15) with progressive proximal muscle weakness, frequent upper and lower respiratory tract infections, orthopnoea and hypercapnic respiratory failure. Over the past 5 years the patient experienced gradually progressive weakness in the upper and lower limbs at the proximal articular surface and was experiencing difficulty climbing stairs and exercise intolerance. At the time of admission he complained of severe type 2 respiratory failure and the arterial blood gas showed severe respiratory acidosis (pH 6.885, pCO2 245 mmHg). The results of detailed investigations such as muscle biopsy, electrophysiological and autoimmune markers were not conclusive. Subsequently, diagnostic confirmation for the diagnosis of late-onset Pompe disease was made by an enzymatic assay that shows a decrease in alpha-1,4-glucosidase activity. Intensive supportive care, physiotherapy, and ventilator weaning led to a gradual improvement in the patient. Conclusion: Progressive proximal myopathy, scapular winging, orthopnoea, recurrent respiratory infections and unexplained hypercapnic respiratory failure are suggestive of late-onset Pompe disease in adolescents. Prompt diagnosis and disease-specific therapy begins with the ability to recognize and be able to test for the correct enzyme.

Keywords: Acid alpha-glucosidase deficiency (also known as Pompe disease), Late onset pompe disease, Hypercapnic respiratory failure, Proximal myopathy, Glycogen storage disease type II.