Regardless of presentation, Pompe disease is caused by the same underlying enzyme deficiency, leading to intralysosomal glycogen accumulation and progressive muscular degeneration. However, the disease encompasses a broad spectrum of clinical phenotypes, which differ in terms of age of onset, extent of organ involvement, and rate of disease progression.
Signs and symptoms can begin anywhere from early infancy up to late adulthood and may present individually or as a collection of symptoms, depending on the patient.
Most Common Signs & Symptoms
All patients with Pompe disease exhibit progressive muscular weakness. Proximal limb and respiratory muscles are the most commonly affected across all ages, while cardiomyopathy is the hallmark sign in infants.
Infants typically present with pronounced hypotonia and severe cardiomegaly. Other signs include frequent respiratory infections, failure to reach motor milestones, and difficulty feeding. Get full details on signs in infants
Children and adults show much greater heterogeneity. The most common clinical manifestations are progressive proximal muscle weakness and respiratory insufficiency,[3-5] ultimately leading to loss of ambulation and the need for ventilation support. Cardiac involvement is rare in this patient population. Get full details on signs and symptoms in children and adults
Disease Progression & Prognosis
In general, earlier presentation of Pompe disease usually correlates with a more aggressive disease course, and most patients who present as infants progress rapidly and die by age one from cardiac or cardiorespiratory failure., , , 
When the disease presents later in life, the rate of progression is much more variable across patients, and because a rapid decline can happen at any time, it can be difficult to predict even for an individual patient. Regardless of rate, Pompe disease is always relentlessly progressive, generally resulting in significant morbidity and often premature mortality, usually from respiratory failure., 
Find out more about Pompe disease progression and prognosis
Hirschhorn, Rochelle and Arnold J. J. Reuser. Glycogen Storage Disease Type II: Acid Alpha-glucosidase (Acid Maltase) Deficiency. In: Scriver C, Beaudet A, Sly W, Valle D, editors. The Metabolic and Molecular Bases of Inherited Disease. 8th Edition. New York: McGraw-Hill, 2001. 3389-3420.
Kishnani PS, Hwu W-L, Mandel H, Nicolino M, Yong F, Corzo D. A retrospective, multinational, multicenter study on the natural history of infantile-onset Pompe disease. J Pediatr 2006; 148:671-676.
Winkel LP, Hagemans ML, van Doorn PA, et al. The natural course of non-classic Pompe’s disease; a review of 225 published cases. J Neurol 2006; 252:875-84.
Kishnani PS, Howell RR. Pompe disease in infants and children. J Pediatr 2004;144:S35-43.
Hagemans MLC, Laforet P, Hop WJC, et al. Impact of late-onset Popme disease on participation in daily life activities: Evaluation of the Rotterdam Handicap Scale. Neuromuscul Disord 2007; 17:537-43.
Slonim AE, Bulone L, Ritz S et al. Identification of two subtypes of infantile acid maltase deficiency. J Pediatr 2000 Aug;137(2):283-5.
Van den Hout HMP. The natural course of infantile Pompe’s disease: 20 original cases compared with 133 cases from the literature. Pediatr 2003 Aug; 112 (2): 332-340.
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