Pompe disease is a hereditary neuromuscular disease affecting infants, children and adults. It is caused due to deficiency of a key enzyme that converts glycogen into glucose. The deficient enzyme is called acid alpha-glucosidase (GAA). Due to lack of this enzyme, glycogen gets accumulated excessively in the muscles, tissue of various organs, most notably in the skeletal muscles and cardiac muscles. It is a disease that causes progressive muscle weakness and various other manifestations.
The enzyme deficiency occurs due to mutation in gene encoding the acid alpha glucosidase (GAAgene). The severity of Pompe disease depends on the age of its onset.In adults the disease can be mild but disabling. Pompe’s disease has no cure. The aim of treatment is to manage symptoms and delay its progression with enzyme replacement therapy.
What Are Causes Of Pompe Disease?
Pompe disease is a rare progressive debilitating neuromuscular disease. It was first identified by Dutch pathologist Joannes C. Pompe in 1932. Later in 1963 scientists were able to identify its inherited linkage with a deficient lysosomal enzyme called acid alpha glucosidase (GGA). Normally the enzyme GAA is involved in breakdown of glycogen into glucose in the tissues.Glycogen is a complex sugar which gets converted to glucose, a simple sugar to provide energy to each and every cell in the body. However, because of deficiency of GAA enzyme glycogen is not processed and as a result gets accumulated in the cells of muscles and tissues.
The deficiency of enzyme is due to mutation in the gene on chromosome 17q 25, that is involved in production of GAA enzyme. The defective gene must be from both the parents to cause Pompe disease. If mutation is in one gene and other gene is normal, than person becomes carrier without any symptom manifestation. Males and females are equally affected. 1 out of 40000 people are known to suffer from this condition. When glycogen gets accumulated without being properly processed into glucose, it can cause severe damage to the cells of tissues, muscles and organs.
Signs And Symptoms Of Pompe Disease In Adults
Pompe disease can be described into three categories depending on the age. The symptoms also differ in these types. There are three types of pompe disease; infantile, juvenile and adult type. Infantile form of Pompe disease progresses rapidly. It leads to cardiac and respiratory failure in first two years after birth.
Compared to that the symptoms of adult onset Pompe disease are relatively mild and progresses very slowly. Nearly two third of Pompe disease is late onset adult variety. It may develop in early adulthood or even later in life.
Here are some of the important symptoms of Pompe disease is adults:
- Progressive weakness of muscles in legs and hips.
- Patient finds difficulty in walking, climbing and getting up from sitting position.
- Waddling gait.
- Frequently loses his balance while walking hence there are several episodes of trips and falls.
- Low back pain.
- Deformity of spine (scoliosis).
- Difficulty in breathing since the lungs is affected in adults, especially after physical work or while lying down.
- Headache in morning.
- Sleepiness and weakness during daytime.
- Repeated infection in lungs causing bronchitis and pneumonia.
- Loss of weight.
- Due to muscle weakness, patient has problem in chewing and swallowing.
Diagnosis Of Pompe Disease
Recognizing Pompe disease is quiet challenging for the doctor because of its rare occurrence. Many other common diseases also manifest similar symptoms. As a result the disease often has diagnostic delays. Nowadays several tests are helpful to determine the extent of muscle weakness and progression of the disease.
Blood, skin and muscle enzyme test is the most confirmatory test. Diagnosis is confirmed when the test shows absence of enzyme or less than the normal range of enzyme. Other clinical tests used for diagnosis are: Blood tests to detect creatine kinase, electromyography, echocardiogram, X-ray chest, and electrocardiogram.
Alternative Therapies For Pompe Disease In Adults
The treatment of Pompe disease is multidisciplinary. It also depends on the age of patient and symptom severity. In adults treatment is aimed to manage the symptoms and give the patient supportive care since the disease is not curable. One of the key factors is to recognize the disease in its early stage for better outcome. Once the muscles are damaged it cannot be reversed. Till few years back the treatment was only supportive care. But recent enzyme replacement therapy (ERT) helps to slow the progression of muscle weakness and improve function of muscles.
Other supportive treatment measures besides enzyme replacement in adults include:
- Physiotherapy to strengthen the weak muscles.
- Breathing exercises.
- Use of cane, walker, wheelchair.
- Use of splints and braces for easy mobility.
- Dietary therapy is needed to maintain healthy weight. Low carbohydrate and high protein diet is usually given the adult patient of Pompe disease. Combing high protein diet with daily exercise is beneficial.
- Occupational therapy for adult so that he can maintain his livelihood.
- Surgical intervention whenever necessary.