Pompe’s Disease (Acid Maltase Deficiency)

Pompe’s disease is caused by a congenital enzyme deficiency in the body

Pathophysiology

1) abnormal buildup of glycogen in the heart, liver, and skeletal muscles 2) cause is deficiency of alpha-1,4-glucosidase (acid maltase)

Signs and Symptoms

1) generalized hypotonia 2) decreased deep tendon reflexes 3) cardiomegaly 4) macroglossia (enlarged tongue) 5) death is usually caused by cardiac failure by age 2 years in the most common (infantile) variant 6) juvenile and adult variants have progressive cardiac, skeletal, and respiratory muscle weakness

Characteristic Test Findings

Laboratory – moderately increased serum CK

Histology/Gross Pathology

Liver – 1) hepatocytes are moderately enlarged with clear areas composed of lysosomes engorged with glycogen Muscle – 2) striking amounts of membrane-bound glycogen present in lysosomes 3) focal loss of myofibrils

Biochemistry

1) alpha-1,4-glucosidase is a lysosomal enzyme 2) buildup of glycogen occurs in the lysosomes because the alpha-1,4 links connecting the long chain of glucose molecules cannot be broken due to absence of enzyme 3) death results from buildup of glycogen

Inheritance/Epidemiology

1) autosomal recessive 2) defect is on chromosome 17q23 3) juvenile- and adult-onset variants have a better prognosis but cardiomyopathy is relentless and death eventually occurs by cardiac failure

Tips for USMLE

1) clinically resembles patients with Werdnig-Hoffman disease 2) hypoglycemia does not occur in this disease