Teen smiles and laughs frequently due to neurogenetic condition

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

- Judith Tan

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

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 Sunday 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 demeanour, 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.

AS occurs in one in 15,000 live births and is caused by a loss of function of one of the genes 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 programmes.