Uncovering Pompe disease

Pompe disease is a rare genetic neuromuscular disorder that is best dealt with when diagnosed early.

Juan du Plessis is a typical bright-eyed two-and-a-half year old boy. When observing him you would have no idea the hardships this young boy has had to go through in his short life and what is sure to come in his future. Juan is one of two children in South Africa currently undergoing treatment for Pompe disease.

Pompe disease is an inherited and often fatal disorder caused by the deficiency of an enzyme acid, alpha-glucosidase’ (GAA). This enzyme is needed to remove a sugar molecule called “glycogen” from the body. Without the enzyme, glycogen cannot be removed or recycled.

The excess glycogen accumulates and is stored in the heart, skeletal muscle and other tissues, causing the progressive symptoms of Pompe disease.

Infantile onset Pompe disease affects an estimated one in 140 000 people. Childhood onset Pompe disease affects an estimated one in 60 000 people. Currently there are only four people diagnosed with Pompe living in South Africa. However, there are probably a great deal more people living with this disease without being diagnosed.

A reason for this is that many physicians are not aware of Pompe disease, or do not think about Pompe disease when diagnosing patients. Professor of Paediatrics and Medical Genetics from Duke University, USA, Professor Priya Kishnani is in South Africa to speak to many physicians around the country informing them of Pompe disease so that fewer cases are misdiagnosed.

“Pompe disease is an undiagnosed condition, we still see many missed diagnoses,” says Kishnani.

The classic symptoms of Pompe disease in infants are delayed motor milestones such as holding their head up or making an effort to sit up right or roll over, an enlarged tongue as well as an enlarged heart muscle. Pompe disease will cause progressive weakness in any muscle of the body.

“The first sign of his (Juan) condition was choking when he fed. I also noticed early on that Juan was ‘floppy’ compared to the other kids of his age. His head tended to roll back when he slept, making him snore,” says his mother, Kelly du Plessis.

It often happens that parents or physicians overlook these symptoms thinking that they will get better. Luckily for du Plessis she had a gut feeling that something was wrong with her son and she kept on pushing until she got the correct diagnosis.

Juan was finally diagnosed with Pompe disease at 11 months old, an age that, Kishnani says, is already very late in the process. Within 11 days of Juan’s diagnosis he was able to start treatment.

“The treatment used is called Enzyme Replacement Therapy (ERT). The goal of this treatment is to prevent, reverse, stabilise or slow down the progression of the disease. The goals of the treatment also depend on which stage the disease is at,” says Kishnani.

Within eight weeks of Juan being on the treatment, du Plessis could already see improvements. He went from making no effort at all to sit up right to being able to do it himself. They also started with intense physiotherapy to help build up Juan’s muscle strength.

ERT involves a six-hour drip once a week, with an hour of observation afterwards. This treatment will need to go on for the rest of the patient’s life. For the du Plessis family they are now able to do the treatment at home, where a nurse comes to put in the drip making it much for comfortable for them.

Without treatment, Pompe disease causes progressive weakening of the muscles, heart and respiratory system leading to profound disability, ventilator dependence and cardiac failure. Fifty percent of people will be in a wheelchair or ventilator dependent within 10 to 15 years from the onset of their symptoms. Pompe disease can occur at any age. However, the earlier the symptoms develop, the more severe the disease.

If infants show any of the symptoms of Pompe disease it is important to take them to a paediatrician who is familiar with the disease.

“When you have seen a child with Pompe disease you will not miss it when you see another child. The problem comes when you haven’t seen the disease and aren’t aware of the symptoms,” says Kishnani.