Juan du Plessis is one of only two patients in South Africa known to have Pompe disease
Juan lies down on white sheets on a bed in a spare room in his parents’ home and holds his breath. The three-year-old boy’s ink-blue eyes twitch. His head, covered with hair as fine as down, moves from side to side as he anticipates the injection below his right shoulder administered by a nurse or his mother. He has endured the same ritual since he was 11 months old.
“We don’t want to do it in his own room because he might start to associate his room with pain,” said his mother, Kelly du Plessis. “That’s why I try to use the nurse as much as I can. I don’t want to be the one who hurts him.”
A round disk with a small pipe attached to it has been implanted beneath Juan’s skin to allow the needle to connect to a vein more easily. Once the needle is inserted, he moves to a couch in the lounge to watch his favourite DVD. It is that ever-smiling purple creature, Barney the Friendly Dinosaur, that makes the first few hours of Juan’s treatment more bearable. Finally, he falls asleep.
For six hours every Friday, Juan is tied to a special machine with a drip that keeps him alive. It releases the biologically manufactured equivalent of an enzyme his body does not produce. Without the enzyme, the sugar molecule glycogen cannot be broken down, removed or recycled and it builds up in the heart and nearly every muscle of the body. Untreated, Juan’s muscles would weaken, probably to the point where he could not stand or walk.
The family lives in Fourways, Johannesburg.
Priya Kishnani, a paediatrician at Duke University in the United States, said without the enzyme many children’s hearts would also enlarge tremendously, thicken and become unable to pump effectively. Patients also often have breathing problems.
Misdiagnosed
Most children with Juan’s condition, known as Pompe disease, die before their first birthday. It is extremely rare and is often undiagnosed, or misdiagnosed. Only one in 100 000 babies are born without acid alpha-glucosidase.
Kishnani, internationally known for her work with Pompe patients, said: “There are special blood tests that can confirm the presence of the disease, but first doctors need to suspect the condition. And because many physicians are unfamiliar with the illness, they fail to test for it.”
She said Pompe disease sometimes mimicked the symptoms of other muscular disorders, making it even harder to diagnose.
Only Juan and one other child had been diagnosed with Pompe disease in South Africa, Kishnani said.
But “if all cases are diagnosed accurately, there should be at least two new Pompe cases identified each year in each of the country’s provinces”. They would include patients who did not display symptoms at birth but develop signs later in life.
Small hill
When he was four months old, Juan’s mother noticed something was wrong with him: he had difficulty breathing and struggled to lift his head. At seven months old, Juan could not sit up straight like other babies or hold his bottle.
Du Plessis took him to several paediatricians, an ear, nose and throat specialist and a specialist at a neurological clinic, but none could determine what was wrong with him.
“At that stage, out of desperation I camped outside the office of a paediatrician that someone had recommended and refused to leave until he had seen my child. It turned out that he was the first and only doctor who said we should test Juan for Pompe disease,” she said.
Although she was relieved finally to know what was wrong with her son, she was upset by the “small hill that had suddenly changed into a mountain. It was such a rare disease and there was just no help or support for me. I’ve often unfortunately thought that it would have been easier to deal with had Juan had cancer – at least people would then understand what I’m going through.”
Du Plessis and her husband both carry an abnormal gene they have passed on to Juan. It did not affect them, but there was a 25% chance that Juan would be born with Pompe disease.
“Had we known this beforehand, we would obviously have thought about having kids a lot more seriously than we did. But there’s no point in blaming and allowing feelings of guilt to swallow you, because it doesn’t change the situation,” she said.
When Juan was finally diagnosed at 11 months, Du Plessis was already pregnant with her second child, daughter Jordyn, who is now 19 months old. Du Plessis became “terrified” that Jordyn would also be born with Pompe disease and went for genetic tests. Amniotic fluid was drawn from her womb to analyse it for abnormalities, but the results showed that Jordyn did not have Pompe, although she could be a carrier of the defective gene.
Special permission
“She will have to get her husband tested one day, because if both of them are carriers they could also have a child with Pompe disease,” Du Plessis said.
In December last year, life-changing enzyme replacement therapy for Pompe disease, known as Myozyme, became commercially available in South Africa. It is manufactured by Genzyme, the same company that produced cultured skin for burn victim Pippie Kruger.
Before it was launched in the United States in 2006, there was nothing to help those suffering from Pompe disease other than pain relief from some of the symptoms.
The oldest known child with Pompe is a 13-year-old American, who was started on the treatment as a baby during a drug trial in the US.
When Juan was put on Myozyme two years ago with special permission because it was not yet registered in South Africa, he could not sit by himself or crawl. But the treatment worked fast.
“Within a month he was able to tuck his knees underneath him as if he wanted to crawl, and within two months he was able to crawl by himself,” Du Plessis said.
According to Kishnani, enzyme therapy could be compared to giving insulin to diabetics.
“Just like diabetes patients don’t have enough insulin, people with Pompe disease lack an essential enzyme. Myozyme provides the missing enzyme. It doesn’t cure Pompe patients from the illness, but it does enable them to live a quality life with the disease.”
Expensive Myozyme is extremely expensive.
Juan’s treatment costs more than R20000 a week and the price will increase as he grows because his body will need more of the enzyme as he gets heavier – and he will have to take it for the rest of his life.
Pompe is listed as a prescribed minimum-benefit condition and Du Plessis’s medical insurance company pays for Juan’s treatment. But as Du Plessis said: “Our medical aid only pays for the cost of the actual medicine. We have to cover all the extras, such as paying a nurse to administer the treatment, drip bags for the machine we use, needles for the infusions …”
The couple had to argue “almost every week” with the company to ensure it would pay for the medicine, until a month ago when they finally received long-term authorisation from their medical aid for Juan’s treatment. It has undoubtedly saved him from an early death, but Du Plessis is racked with doubt and “unknowns”.
“Because Myozyme treatment hasn’t been around for that long, we don’t really know what it will do in the long term. Today our son can walk and talk, also with the help of intensive speech, occupational and physiotherapy. We’re really hopeful that his progress will continue throughout his life. But, at the same time, we want to err on the side of caution. We just have to take it day by day.”
Tell-tale signs of Pompe
Early onset (infantile) symptoms begin in the first months of life with feeding problems, poor weight gain, muscle weakness, floppiness and head lag. Respiratory difficulties are often complicated by lung infections. The heart is often grossly enlarged. Many infants with Pompe disease also have enlarged tongues. Most babies die from cardiac or respiratory complications before their first birthday.
Late onset (juvenile or adult) Pompe disease can be as early as the first decade of childhood or as late as the sixth decade of adulthood. The primary symptom is muscle weakness progressing to respiratory weakness and death from respiratory failure after several years.
Source: National Institutes of Health, US government, ninds.nih.gov/disorders/pompe/pompe.htm
Mia Malan works for the Discovery Health Journalism Centre at Rhodes University