Pompe disease is a rare genetic disorder caused by a deficiency of the enzyme acid alpha-glucosidase (GAA), leading to an abnormal accumulation of glycogen in various tissues of the body. The most visible accumulation is in the muscles. This condition can manifest in two distinct forms: infantile-onset Pompe disease and late-onset Pompe disease, often referred to as IOPD and LOPD.

Infantile-onset Pompe disease presents in early infancy and is characterized by severe and rapidly progressive muscle weakness, cardiac involvement, and respiratory issues. Late-onset Pompe disease typically manifests later in life, often during childhood, adolescence, or adulthood. It has milder and more variable progression of symptoms, primarily affecting the skeletal muscles and respiratory system. While both forms share the same underlying genetic cause, their clinical presentations and prognoses differ significantly.

Enlargement of the heart (cardiomegaly) tends to be more commonly associated with infantile-onset Pompe disease. In infantile-onset Pompe disease, the heart is often significantly affected, leading to cardiac complications at an early age. Although this can be seen in late-onset Pompe disease, it is not nearly as common.

Common Symptoms of Pompe disease

Infantile-onset Pompe disease
  1. Muscle weakness: This is one of the primary symptoms and can affect various muscle groups, including the muscles involved in breathing, sucking, swallowing, and crawling.
  2. Hypotonia: Babies with Pompe disease often have weak muscle tone, which can lead to difficulties with feeding, poor head control, and delayed motor development. This is sometimes called ‘floppy baby’.
  3. Enlarged heart (cardiomegaly): The accumulation of glycogen in heart muscle cells can result in an enlarged heart, leading to heart problems such as congestive heart failure. This is an important marker that helps distinguish between infantile-onset and late-onset Pompe disease.
  4. Respiratory problems: Pompe disease can affect the muscles responsible for breathing, leading to breathing difficulties, recurrent respiratory infections, and potentially respiratory failure.
  5. Poor weight gain and growth: Due to feeding difficulties and muscle weakness, infants with Pompe disease may have difficulty gaining weight and growing at a normal rate.
  6. Enlarged liver (hepatomegaly): The glycogen accumulation can also occur in the liver, causing it to become enlarged.
Late-onset Pompe disease
  1. Progressive muscle weakness: Less severe than infantile-onset Pompe disease, late-onset Pompe disease leads to progressive muscle weakness that may begin at any time from childhood to later in life.
  2. Respiratory problems: Muscle weakness can affect the respiratory muscles, causing shortness of breath, difficulty breathing, and respiratory insufficiency.
  3. Fatigue and exercise intolerance: Individuals with Pompe disease may experience fatigue and have limited stamina, making physical activities challenging. This can be challenging to notice because decline can be slow.
  4. Musculoskeletal complications: Over time, the progressive muscle weakness can lead to musculoskeletal complications such as scoliosis and lordosis (curvature of the spine), and joint contractures (limited range of motion).