SINGAPORE – Mr Yeo Wee Chong, 36, used to play the bass clarinet in a concert band.

His career as a musician was abruptly cut short, however, when he was diagnosed with Pompe disease at the age of 29.

Pompe disease is a rare genetic disorder that can result in respiratory failure, a significant complication due to progressive respiratory muscle weakness, especially affecting the diaphragm. 

“I became extremely drowsy and unable to focus properly. On the advice of my family doctor, I went to the emergency department. I was admitted to the ICU (intensive care unit) and subsequently intubated while the doctors figured out the root cause of my feeling poorly,” said Mr Yeo, who is currently between jobs.

It took doctors another two to three weeks before they diagnosed his condition.

Dr Yong Ming Hui, a consultant from the department of neurology at the National Neuroscience Institute at Singapore General Hospital, told The Straits Times that affected patients lack the acid alpha-glucosidase (GAA) enzyme needed to break down glycogen.

Glucose, the fuel used by the body’s cells for energy, is normally stored as glycogen in the liver and muscles. In Pompe disease, glycogen builds up in the cells of certain organs and muscles, impairing their normal function. This leads to progressive muscle weakness, mobility problems and affected breathing.

Mr Yeo was told he could not continue playing the bass clarinet because of the weakness of his diaphragm. “This was a particular sore point for me as I was active in performing with bandmates and that was a big part of my social life and identity,” he said. “But I accepted and recognised the situation, and just try to do my best with what I have on hand.”

The reported incidence of Pompe disease is around one in 40,000, with some literature citing it as one in 17,000 to 37,000 in Asia.

Doctors say that when Pompe disease starts in infancy, it usually progresses faster and with greater severity compared with later onset, when the patient is an adult.

“(Infant patients) develop severe symptoms in the first few months of life. They classically have generalised weakness and loss of muscle tone, feeding difficulties, and continue to develop respiratory failure and require ventilator support. Important organs are also affected, leading to an enlarged heart and liver,” Dr Yong said.

According to medical literature, some cases even develop enlarged tongues. 

“If left untreated, the disease is fatal by the age of one to two years,” she added.

Adult patients with Pompe disease, on the other hand, have a less severe form that progresses gradually.

“The age at which the symptoms start can even be when they are in their 60s, and the severity depends on the degree of the deficiency (of the enzymes). These symptoms can include difficulty in walking, the inability to perform sit-ups, exercise intolerance and fatigue, shortness of breath, and sometimes difficulty in swallowing,” Dr Yong said.

Such adults generally do not develop heart failure or liver enlargement, but abnormalities of blood vessels in the brain have been diagnosed in a small number of patients, she added. On rare occasions, the latter can lead to a stroke.

The life expectancy for adult patients with late-onset Pompe disease varies with age of symptom onset and disease severity, but it decreases in patients with respiratory failure.

When Pompe disease is suspected in a patient, a dried blood spot test is performed to confirm abnormally low GAA enzyme activity in the subject. Then the diagnosis is confirmed with genetic testing.

Adults get a diagnostic test called electromyography, where a small needle electrode checks muscle activity to confirm if there is muscle damage.

Sometimes, a muscle biopsy is used to diagnose the disease, Dr Yong said.

Mr Yeo’s condition is currently managed by a team of doctors, nurses and allied health professionals from SGH, including a team of neurology pharmacists.

As his breathing was affected by the condition, he uses a bilevel positive airway pressure (Bi-PAP) machine at night, in case his airway gets blocked or he cannot breathe deeply when he sleeps. The Bi-PAP device pushes air into his lungs, to keep his airways open.

Mr Yeo said the initial weeks in the ICU were the hardest. His condition had to improve so he could get off the ventilator.

“A tracheostomy would have been needed if I was unable to do so – that was the most stressful part,” he said, referring to a surgical procedure where an opening is created in the trachea, or windpipe, to facilitate breathing. 

He needs to be on medication and bi-weekly enzyme replacement therapy for life, which costs $55,000 a month.

“The added financial burden of such expensive treatment is an ongoing source of stress,” he said.

“Thankfully, the Rare Disease Fund (RDF) now covers the costs of most of my medication. This has been an immense relief, as I can now focus on managing my health and maintaining my quality of life, without the burden of medical expenses that would have otherwise been beyond my means,” he said.

RDF, a charity fund that is managed by the KK Women’s and Children’s Hospital Health Fund (KKHHF) and supported by the Ministry of Health, provides long-term financial support for patients with rare diseases and who require treatments involving high-cost medicines. KKH and SGH are both part of the SingHealth group.

Receiving RDF’s help was a milestone and “is a big source of encouragement for myself”, Mr Yeo said. “As someone living with Pompe disease, managing the condition is already physically and emotionally demanding.”

On a brighter note, he has regained enough strength to perform ad hoc with the band again since 2023.