Are there earlier onset, later onset, or variant forms of Pompe disease?
Pompe disease has an early onset, severe form called infantile onset Pompe disease (IOPD) and a later onset form, called late onset Pompe disease (LOPD). A person has IOPD when they have no acid maltase (also known as acid alpha-glucosidase) enzyme function and are born with muscle weakness and a larger than normal heart.
When a person has LOPD, they have a little enzyme function. Symptoms of LOPD can start anywhere from 1 year of age to anytime in adulthood. People with LOPD usually do not develop a large heart (cardiomyopathy). Some changes in the gene (called mutations or variants) causing Pompe disease, GAA, are known to be severe and some are known to be milder. Individuals with Pompe disease will typically have two different mutations. If one of these mutations is milder (regardless of whether or not the other one is mild or severe), they usually have LOPD.
Babies with Pompe disease are often diagnosed based upon the symptoms seen at birth, but later onset Pompe disease may be more difficult to diagnose and require the involvement of multiple doctors who specialize in areas such as neurology (the nervous system) and metabolics (how the body turns food into energy). The best person to help figure out if someone has Pompe disease is their main doctor, who can then order testing or make referrals to the appropriate specialists.
Pompe Disease - Health Care Professionals: Genetics & Epidemiology https://www.pompe.com/en/healthcare-professionals/genetics-epidemiology/mutations.aspx