Pompe disease is a genetic condition, but, as some rare diseases usually are, very serious.
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Our body uses the enzyme acid alfa glucosidase (GAA) to break down complex sugars. One of them is called glycogen and if there is a the deficiency of GAA glycogen can't be broken and it builds up in the cells. As you might expect when it builds in organs and tissues, that leads to the break down of those organs, and muscles are especially hit.
Mutations in the GAA gene are a cause of three variations of Pompe disease. First is one that appears after birth and it's called classic infantile onset, another appears 12 months or so after birth and is called non classic infantile onset, and another appears later in the kid's life and is called late onset.
Pompe disease is a genetic condition so that means it is inherited from a parent. That's bad news.
However, another bad news is that usually both parents show no symptoms.
But it gets even worse. There is a range of symptoms, depending on when the disease hit.
In the classic type there are weak muscles, enlarged liver, failure to gain weight and grow, trouble breathing, feeding problems, respiratory system infections, hearing problems.
In the non classic type there are: problems with motor skills, delayed moto skills, muscles get steadily weaker, there is an abnormally large heart, and there are breathing problems.
In the late onset type there are enlarged heart, muscle pain, the legs and the trunk get weaker, there are breathing problems, frequent lung infections, shortness of breath physical strain, morning headaches, tired during the day, can't swallow easily, irregular heartbeat, hearing difficulties, higher levels of enzyme creatine kinase (ck) that helps the body and provides energy to cells.
It is important to have all those symptoms in mind because they differ regarding the age of the patient.
How it is diagnosed? Since this is a genetic disorder, a blood sample is taken and enzymes are studied and counted. Lung capacity measurement and a test that measures how well the muscles work called electromyography are done too.
A pseudo-deficiency allele, p.[G576S; E689K] is relatively common in Asian populations and leads to falsely low measured enzyme activity. It was recently reported in 3.9% of Japanese. It has also been found in the Taiwanese population.
The therapy exists and it is an enzyme replacement therapy (ERT). A drug alglucosidase alfa is given intravenously and a genetically engineered enzyme acts as the natural acid alfa glucosidase enzyme.
Other specialists treat symptoms from their field.
Pompe disease can occur anytime from the newborn period through late adulthood. Patients who may be diagnosed later in life, because of neuromuscular and/or pulmonary symptoms, often recall symptoms in childhood that were not recognized as being pathologic.
Without treatment, infants with Pompe disease die. The rest have breathing and heart problems, and of the course there is muscle weakness because muscles are hit the most. Most patients need oxygen and wheelchairs later. ■