Mrs Wendy Wong was set for a senior managerial role in her firm until the birth of her second son, Mr Wong Yong En, now 21, required her full attention.

She has an older son, 23, who does not have any health condition and works at an engineering firm.

At the Dignity Mama bookstore, Mrs Wong gets an allowance of $5 an hour - a far cry from what she could have made.

She said: "I was one of the few human resource executives in a startup firm and I knew if I had continued, I could have climbed up the corporate ladder and would have been a successful manager or someone in a senior position".

She said that the first 10 years of her second son's life were difficult.

"There was no room for my hopes and dreams. All my energy and time was spent on him."

Mrs Wong recounted how she found out her son had epilepsy.

"I knew about it six months after he was born. I was holding him when he suddenly started shaking violently in my hands.

"His hands became rigid, his body stiffened and his eyes rolled up until all I could see were the whites of his eyes. He also foamed at the mouth."

The doctor told her that each time her son suffered a seizure, there would be a few steps back in his mental development.

She explained: "It slows down his learning ability and motor skills."

To teach her son, Mrs Wong had to repeat her instructions several times. But on many occasions, her patience was tested when he made a mess or refused to learn.

Mrs Wong said she blamed herself.

"I kept asking, 'Why me?' Did I do something wrong during my pregnancy? Was I too greedy and ate something I was not supposed to?

"I thought that since my first son had no problems, I would not have to worry about Yong En. But I was wrong and I thought it was me."