Prevalence and Incidence • Worldwide prevalence on both forms of the disease is reported ~ 1 in 40,000 individuals. • Incidence of LOPD in Taiwan and Austria is 1/26,466 and 1/8,684 respectively. • Frequency of LOPD is estimated at 1 in 57,000 individuals.
	Age of onset Infantile-onset Pompe disease (IOPD): • Onset before age 12 months with cardiomyopathy.  Late-onset Pompe disease (LOPD):  • Onset before age 12 months without cardiomyopathy.  • All individuals with onset after age 12 months.

 

Classic form of the disease presents with hypertrophic cardiomyopathy and heart failure. 

Both infantile-onset and late-onset forms can present with muscle weakness and respiratory failure. Other shared clinical features may include hepatosplenomegaly and macroglossia.

However, the severity and onset of these symptoms can differ between the two forms of the disease, with the infantile-onset form being more severe and life-threatening than the late-onset form.

Infantile onset Pompe disease: This type may present from the first days after birth and is characterized by the following:
• Hypotonia since birth.
• Hyporeflexia/areflexia. 
• Contractures and joint deformities, such as lordosis and scoliosis.
• Pneumonia and upper respiratory tract infection.
• Respiratory insufficiency.
• Hypertrophic cardiomyopathy.
• Congestive heart failure.
• Conduction disorders.

Late onset Pompe disease (LOPD) - This type is characterized by the following:
• Progressive limb-girdle weakness followed by the diaphragm and accessory respiratory muscles.
• Hyporeflexia.
• Gait disturbances.
• Myalgia and cramps.
• Amyotrophy.
• Dyspnea on exertion.
• Orthopnea.
• Sleep apnea.
• Frequent respiratory tract infections.

Blood biochemistry analysis can provide important information for diagnosing Pompe disease, with elevated levels of creatine kinase (CK), transaminases, and lactate dehydrogenase (LDH) being sensitive but nonspecific indicators. 

Measurement of α-glucosidase activity in dried blood spots (DBS) is essential for diagnosis, along with confirmatory tests such as sequencing of the GAA gene. 

Imaging tests such as muscle MRI and chest radiography can provide valuable information, with echocardiography being particularly useful for detecting cardiac abnormalities.

Currently, there is no cure for Pompe. Enzyme replacement therapy (ERT) has been a major therapeutic advancement and is the treatment of choice. ERT has been shown to improve patients’ lives, however, its benefits may be attenuated by antibody formation.

The most serious complication is progressive muscle weakness, which can result in respiratory failure and ultimately, death. Other potential complications include developmental delays, feeding difficulties, aspiration pneumonia, and hearing loss. Without treatment, the infantile form of Pompe disease can be life-threatening, and many infants do not survive beyond their first year.