Rare genetic condition keeps him smiling, laughing and hugging others

Mr Lucas Oon, who has Angelman syndrome, and his mother Vanessa Oon, pictured on Feb 17. The Straits Times/Asia News Network

SINGAPORE – Laughter fills the consultation room whenever Lucas Oon, 17, is with the team managing his care – pediatric neurologist Jeremy Lin, assistant nurse clinician Kimberly Quek and physiotherapist Melody Por.

Lucas has Angelman syndrome (AS), a rare neurogenetic condition characterized by a happy demeanor, with frequent smiling and laughing, and an easily excitable nature.

“He is happy every day, always smiling and laughing without a worry in the world,” said his mother and full-time caregiver, Mrs Vanessa Oon.

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In fact, Lucas is such a social butterfly who loves giving hugs that he sometimes scares strangers by trying to pull them towards him to interact with them, Mrs Oon told The Straits Times.

It is challenging for Mrs Oon, 49, to manage Lucas’ enthusiasm when it comes to making friends with strangers.

“I often need to explain his condition to them. While most are sympathetic, there are still those who feel scared or get angry. One has even threatened to call the police,” she said.

Beyond the happy demeanor, there are sombre realities: Lucas has physical and intellectual disabilities. He relies on gestures to communicate with others. While the condition does not affect his life expectancy, it is incurable.

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AS occurs in one in 15,000 live births and is caused by a loss of function of one of the genes (UBE3A gene) in the 15th chromosome inherited from the mother.

“(The condition) only gets more obvious when the child grows… In Singapore’s context, we might be looking at one or two cases each year,” said Dr Lin, who works at the Khoo Teck Puat – National University Children’s Medical Institute at the National University Hospital.

Dr Lin, who is also an assistant professor at the NUS Yong Loo Lin School of Medicine, said there had not been much awareness of the condition until recently, when Irish actor Colin Farrell spoke publicly for the first time about his older son James, who has AS.

Farrell launched a foundation to support adult children with intellectual disabilities through advocacy, education and innovative programs.

Dr Lin said AS is usually diagnosed after the child is two or three years old. There were two or three cases of children with the condition in Singapore who were labelled as having cerebral palsy, “until people relooked them with a different lens”, he added.

Dr Lin said the misdiagnosis could have occurred because both conditions share overlapping symptoms, and cerebral palsy is much more common than AS.

Unlike typical cases, Lucas was diagnosed at five months old.

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“Lucas’ case was very unique. He went straight for genetic testing at the beginning, and that was how his AS was found out,” Dr Lin said.

Mrs Oon recalled the first seizure Lucas had at two months old.

“(It was caused by) a fever from a urinary tract infection. He was taking the medication prescribed by a GP when he developed seizures and was trembling,” she said.

The series of seizures eventually led Lucas’ doctors to order genetic tests, which were sent overseas for analysis.

After a three-month wait, Lucas was officially diagnosed with AS.

He was referred to the Early Intervention Program for Infants and Children at the Early Childhood Development Agency. After he turned two, he attended Rainbow Centre, where he learnt to walk and swim.

Through early intervention, physiotherapy and occupational therapy, Lucas was able to hone his motor skills and communicate with his mother through text cards.

“There are a few core characteristics, such as (difficulty with) expressive speech. These children (with AS) may understand more than they can express themselves,” Dr Lin said.

READ: British man with rare genetic disease inspires 2-year-old with same condition

“They also have issues with standing and walking. If they are able to, (it involves) broad-based gait and unstable movements.

“Of course, the characteristic that stands out most is the happiness. They are always laughing, to the extent that some people may say inappropriately.”

Lucas was 10 when he was referred to Dr Lin, and has been under the care of his team for the past seven years.

“The main issue that brought him to see us was actually the repeated seizures. It is very common for AS patients to have epilepsy, and at that point, perhaps he was going through puberty, there were a lot of unprovoked seizures (and) he was hospitalized,” Dr Lin said.

“I felt there was a need to manage or to control his epilepsy because it affected his quality of life.”

Dr Lin noted that there is a limit to the amount of medication that can be given due to the potential side effects on the liver and kidneys.

Lucas was 10 when he was referred to Dr Lin and has been under the care of his team for the past seven years. The Straits Times/Asia News Network

“We started to think about non-pharmacological (treatment), so we implanted a vagus nerve stimulator on Lucas’ left chest. It is a battery-operated device that is supposed to last seven years, and it delivers electrical currents to try to stop seizures,” he said.

“He has had the device for probably close to five years, and his seizure control has actually improved significantly.”

His medical care team is also focused on improving Lucas’ mobility as part of a holistic care plan.

“He grew very tall and that was when all the orthopedic complications set in, and he started to lose his mobility. That was when we involved the physiotherapists,” Dr Lin said.

Lucas recently underwent tendon release surgery on his leg to improve his mobility.

Ms Quek, the assistant nurse clinician, worked alongside Dr Lin to calibrate the settings of Lucas’ stimulator. She also guided Mrs Oon on how to handle the challenges of raising a child with special needs. Such problems include difficulty in managing the child when he grows older and stronger, as well as caregiver depression.

Today, Lucas is able to walk with the assistance of a pacer walker, which lets him enjoy the outdoors.

He lives in a two-room rental flat with his mother and an elder brother, who is in government service. Mrs Oon said she feeds and changes Lucas on her own, without giving further details about their life.

Like other parents with children who need professional care, Mrs Oon is worried about Lucas’ future.

Now attending AWWA School, he is turning 18 and will be out of the system by the end of 2025.

“I hope there will be subsidized daycare centers set up for adults with special needs so that elderly parents can leave them there during the day… and perhaps a home when the parents are no longer around,” she said.

“I hope he will always be happy, and that he won’t suffer any more seizures.”