By Genevieve Jiang

She scored a creditable 220 in the Primary School Leaving Examination (PSLE) which, considering she used to score zero in previous tests, is a small miracle in itself.

The bigger miracle is that Sia Jin Zhu did this despite having little control over her movements. She needs to be strapped tightly to a wheelchair and propped up with four small pillows, so that her body and head does not loll forward.

The 12-year-old girl has muscular dystrophy, a genetic disorder which causes her muscles to slowly waste away.

She has her sister, Miss Sharon Sia, 26, to thank for her remarkable turnaround.

For the past four years, Miss Sia has been Jin Zhu's main caregiver.

While most people in their 20s are busy with their careers or social life, she has put her future on hold so that her younger sister can have one.

Miss Sia said: 'I get satisfaction and happiness from giving my sister happiness. It's not something many people can understand, but I'm content.'

Hard to chew food

Her life revolves around her sister's.

She wakes up at 6am daily to prepare food for the family, takes Jin Zhu to Greenridge Primary - a 15-minute walk from their five-room flat at Bukit Panjang.

During lessons, Miss Sia stands outside the class with her own set of primary school textbooks and diligently takes notes. This is because Jin Zhu cannot write fast enough to keep up with the class.

At home, she bathes Jin Zhu, does the household chores and prepares dinner.

Jin Zhu takes at least an hour to eat, because her weak muscles makes chewing difficult.

At night, Miss Sia helps her sister with her homework.

Every Friday, she takes Jin Zhu to the Society for the Physically Disabled for physical therapy. On weekends, she takes Jin Zhu out for walks or shopping for toys.

Their parents sensed something wrong when Jin Zhu was 2 months old. She had little control over her movements and could barely lift her head.

She was diagnosed soon after and went for weekly physiotherapy at the KK Women's and Children's Hospital (KKH).

After two months, she stopped therapy as the family could not afford the cost - about $120 every month.

Her mother, 49, takes home $400 a month as a part-time hawker assistant and her father, 50, earns about $500 doing odd jobs.

The mother was the main caregiver for seven years, but it was a trying time.

Miss Sia said: 'My mother found it hard to accept my sister's illness because she blamed herself for it.

'Apart from school, she hardly took Jin Zhu out because she felt ashamed when people stared at her.'

Miss Sia's parents declined to be interviewed.

Even as a teenager, Miss Sia was saddled with responsibilities that her classmates did not have.

She said: 'I could not stay late in school for projects, take part in after-school activities, or go shopping or for movies.

'I even missed many lessons to rush home from school every day to help my mother with household chores and to take care of my sister before my mother went to work at night.

'Some days, I would go home to find diapers strewn all over the floor and my mother in tears or staring into space.'

Dropped out of school

As a result, Miss Sia was unable to complete her diploma in mechatronics at Singapore Polytechnic. She dropped out after about five months.

She took up accounting at the Clementi West Institute of Technical Education (ITE).

After she left school in 2004, she also tried three part-time jobs, but had to quit after two weeks because of her commitments at home.

A relative helped to hire a maid for the family, but four maids came and went within a few months as they could not cope, Miss Sia said.

At the time, Jin Zhu was doing poorly in school, failing almost every subject, and sometimes scoring zero.

At the end of 2004, Miss Sia decided to look after Jin Zhu full-time.

For the next two years, she juggled her home duties with night classes in higher accounting and secretarial skills at ITE twice a week.