Infantile Onset

The infantile-onset form of Pompe disease typically presents rapidly within the first few months of life, often with initial observations of profound hypotonia, muscle weakness, and a "floppy baby" appearance. Feeding difficulties and respiratory problems may manifest at early stages as well. Clinical investigation usually reveals moderate hepatomegaly and sometimes macroglossia, but the hallmark sign is marked cardiomegaly with left ventricular thickening, which may result in outflow track obstruction.

Head-lag may be clinically observable in infantile-onset patients.

A 2001 review studied the cases of 78 infantile patients (77 of whom were less than two years at age of onset) to determine the frequency of common clinical features. They found that 96% of patients demonstrated muscle weakness, 95% demonstrated cardiomegaly, 82% demonstrated hepatomegaly, and 65% demonstrated macroglossia. In comparison, they noted that of 51 late-onset patients (24 juveniles, 27 adults), only 2% displayed cardiomegaly, underscoring the distinguishing factor of cardiac involvement in the infantile-onset form.^[1]

Progressive muscle weakness

Profound hypotonia

Macroglossia (and in some cases, protrusion of the tongue)

Cardiomegaly (massive)

Respiratory insufficiency

Failure to meet developmental motor milestones

Hepatomegaly (moderate)

Difficulty swallowing, sucking, and/or feeding

Laxity of facial muscles

Areflexia

Although patients may not exhibit obvious symptoms at birth, the course of infantile-onset Pompe disease typically progresses rapidly. Spontaneous movements decline as muscle deterioration advances, and weakening of the diaphragm and other respiratory muscles compounded by pooling secretions begins to impair respiratory function. Most patients are never able to ambulate, but in contrast, mental development is generally not affected. Death from cardiorespiratory failure usually occurs by age one. ^{[1, 4]}

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1. Hirschhorn, Rochelle and Arnold J. J. Reuser. Glycogen Storage Disease Type II: Acid Alpha-Glucosidase (Acid Maltase) Deficiency. In: Wonsiewicz M, Noujaim S, Boyle P, eds. The Metabolic and Molecular Bases of Inherited Disease. 8th Edition. New York: McGraw-Hill; 2001; 3389-3420.

2. King, Frank J. Acid Maltase Deficiency Myopathy. eMedicine Specialties. Available at: http://www.emedicine.com/pmr/topic2.htm . Accessed November 7, 2002.

3. Personal communication with Jennifer Hofstein, MS, RD, and Alfred Slonim, MD, at North Shore University Hospital Pediatric Endocrinology & Metabolism, Manhasset, New York.

4. 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.