SINGAPORE – When people hear the word “MMA”, they likely think of mixed martial arts, a full-contact combat sport that combines various fighting styles.
But for property agent Daniel Lim, 56, and his wife Michelle Tan, 54, MMA has an entirely different meaning. It is an abbreviation for Methylmalonic Acidemia, the genetic condition their daughter Francesca is living with.
MMA is a rare genetic metabolic disorder that affects the body’s ability to break down certain proteins properly. When this process fails, toxic substances, particularly methylmalonic acid, accumulate in the blood, leading to serious health complications.
The life expectancy for someone with MMA varies significantly by type and age of onset. However, patients with severe cases with early onset have a poor prognosis, with many patients dying within 1½ years.
Typically detected at birth through routine newborn screening, Francesca, 17, was not diagnosed until she was four months old.
“She was not drinking well and was not even keeping her milk down. She vomited regularly as soon as she was breastfed. We took her to the GP (general practitioner) and to her paediatrician. Both told us the same thing – that it was milk reflux and that it was normal for babies to throw up,” Ms Tan, a procurement executive, told The Straits Times.
What Francesca actually has is a potentially life-threatening condition.
“It was a weekend in 2008, and I recall us trying to play with her, but she wasn’t responding. We rushed her to KKH (KK Women’s and Children’s Hospital),” Ms Tan said.
“You could call it either a coincidence or a blessing, as the doctor who was on duty in the emergency room at the time happened to be Dr Tan. She examined Francesca and asked for tests to be carried out. It was the following day when she diagnosed Francesca with MMA.”
Francesca Lim, 17, lives with a rare genetic condition that affects her body’s ability to break down certain proteins properly, causing toxic substances to accumulate in the blood, and resulting in serious health complications.
The “Dr Tan” Francesca’s mother was referring to is Associate Professor Tan Ee Shien, who heads Genetics Service at KKH.
To explain how MMA affects the body, Prof Tan drew the analogy of a complex factory in which a specific assembly line dedicated to breaking down certain proteins from food is given a faulty instruction manual.
“These errors affect the production of special proteins called enzymes – (the) workers on the assembly line. These enzyme workers either do not show up for work at all, or show up but cannot do their job properly. As a result, certain substances that should be broken down end up accumulating in the body, like packages piling up on a broken conveyor belt,” she said.
Prof Tan said that when the specific enzyme affected by MMA is not working correctly, these amino acids, which are the building blocks of proteins, store up to toxic levels in the blood and tissues, leading to the various symptoms and complications associated with MMA.
They include vomiting, dehydration, lethargy, developmental delays, seizures and an enlarged liver, with long-term complications such as intellectual disability, movement disorders, chronic kidney disease and pancreatitis.
MMA is considered very rare, with an estimated global prevalence of around one in 50,000 to one in 100,000 in newborns.
Francesca is the seventh person living with MMA in Singapore. Two more were diagnosed after her.
Prof Tan stressed the importance of newborn screening for MMA in effectively managing this serious metabolic disorder, enabling doctors to take timely action within the first few days of a baby’s life.
“A baby who seems healthy at birth might suddenly become seriously ill – refusing feeds, vomiting, or becoming unusually drowsy. As MMA is so rare, doctors often investigate more common conditions first, leading to precious time lost in reaching the correct diagnosis. These delays are critical as symptoms often appear when the baby starts regular feeding, triggering a metabolic crisis,” she said.
“(It is) only during hospital admission, and after ruling out more common conditions, would tests finally reveal the underlying MMA. By then, damage to the brain, kidneys or other organs may have already occurred.”
Early detection through screening allows medical teams to implement specialised diets and treatment plans immediately, preventing crises and significantly improving the child’s health outcomes.
However, having been born at a private hospital, Francesca was not tested at birth for any genetic condition, including MMA. All babies born at public hospitals are screened for MMA at birth under the National Expanded Newborn Screening programme.
The special diet for MMA patients is a low-protein one that focuses on restricting specific amino acids (methionine, threonine, valine and isoleucine) found in high-protein foods such as meat, dairy and eggs.
Francesca is the seventh person living with MMA in Singapore. Two more were diagnosed after her.
This diet comprises special metabolic formulas and medical foods to supply essential nutrients and calories, and provides enough energy to promote normal growth but avoids metabolic instability.
“We order a special protein mix directly from the United States and make sure she keeps to her regimen of medication and supplements. So far, she has been really good at following it,” Mr Lim said.
Prof Tan said the rare nature of MMA also poses unique challenges for doctors managing the condition, as it is often the first time many of them have come across patients with this disorder.
Mr Lim, whose job is flexible enough for him to be Francesca’s primary caregiver, recalled an incident when the teen was taken by ambulance to an acute hospital closest to their home.
Accustomed to frequent trips to the emergency room, Mr Lim has made it a habit to keep Francesca’s medical records readily accessible for when she needs urgent hospitalisation.
“She had over-hydrated herself and suffered a seizure. I understand that while the doctor at the emergency department had his protocols to follow, he should have taken the time to listen as I explained her condition. He was not even paying attention and kept dismissing me. I finally had to call KKH to have Prof Tan speak to him,” Mr Lim said.
Prof Tan explained that in busy emergency departments, doctors often follow well-established protocols to address common symptoms such as fever or vomiting, ensuring rapid and efficient care for a high volume of patients.
“Understanding rare metabolic conditions like MMA is crucial for both healthcare workers and the wider public,” she said.
“For healthcare workers, this knowledge helps them appreciate why these patients need specific protocols and urgent attention, even when presenting with seemingly common symptoms.”
With the complex nature of her condition, Francesca is a “frequent flier” at KKH – requiring biannual monitoring, is susceptible to metabolic crises, and needs various specialist consultations.
Mr Lim, who has to collect her medication every Tuesday, has also earned the nickname “Mr Tuesday” from the nurses and pharmacists at the hospital.
“Any illness, even a minor infection, can trigger a crisis requiring immediate medical attention, and (her) treatment plans often need regular adjustments. When Francesca was younger, she had the typical childhood viral illnesses, and they sometimes triggered metabolic crises that required admissions,” Prof Tan said.
Francesca used to attend a mainstream primary school but when she was 11 years old, her parents transferred her to APSN Chaoyang School, a special education school, “to help her cope with learning at her own pace”, Mr Lim said.
Francesca now attends APSN Delta Senior School for vocational training.
“She is being trained in culinary skills but due to her condition, being in a commercial kitchen would not suit her,” Mr Lim said.
He expressed hope that given her gentle, shy demeanour and weak muscles, she could be placed in a work environment that best suits her abilities.
“Perhaps opening a small bakery or, hopefully, working in a hospital as a nursing aid. There, she will be at a place she is most familiar with,” her father added.
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