Infantile-onset Pompe disease
This becomes apparent from within a few days to a few months of birth. Infants typically experience myopathy (muscle weakness), hypotonia (poor muscle tone), and a severe thickening of the heart muscle called hypertrophic cardiomyopathy (see entry Cardiomyopathies in Children). The cardiomyopathy results in heart failure (i.e. accumulation of fluids on the lungs) and hepatomegaly (an enlarged liver). The combination of heart failure and with the decreased muscle strength means that children often have with breathing difficulties. Affected infants will also fail to gain weight and grow as expected. They also can suffer from swallowing difficulties. Sadly, if left untreated, this form of Pompe disease can lead to death from heart failure in the first year of life.
Non-classic Infantile-onset Pompe disease
This form of infantile-onset Pompe disease also appears by one year of age. Symptoms are the same as infant-onset except for the absence of the cardiomyopathy.
Late-onset Pompe disease
The late-onset type of Pompe disease may not become apparent until later in childhood, adolescence or more commonly adulthood. Late-onset Pompe disease is usually milder than the infantile-onset forms of this condition and again does not involve the heart. Most individuals with late-onset Pompe disease experience progressive muscle weakness, especially in the legs and the trunk and including the muscles that control breathing. As the condition progresses, breathing problems can become more serious.