Zhang Ying, the mother of Velo Zou, a 3-year-old patient with spinal muscular atrophy, or SMA, in Shanghai

During the year after my son was diagnosed, I cried almost all the time. My husband named our children after bicycles because he is so fond of cycling, but it was as if the chain on our son's bike had broken and it was game over.

After the diagnosis, I wrote a long article on Sina Weibo to encourage couples with a history of family disease to take genetic tests to avoid deaths.

I lost my sister to muscular atrophy when she was 13 and I was 6. The public, and even doctors, had little knowledge of rare diseases at the time. After my son's diagnosis, I associated his case with my sister's.

The article attracted 270,000 clicks and several people said they had family members with similar symptoms.

My article was meaningful. One day, I will witness what happened to my sister strike my son, but I hope many others can avoid such a tragedy.

When both parents are SMA carriers, there is a 25 percent chance that their child will be unaffected, a 50 percent chance of the child carrying the SMA gene and a 25 percent chance of the child developing SMA.

If a woman becomes pregnant again, couples who have had a child with SMA can have a DNA test conducted on the fetus through amniocentesis (a procedure used in prenatal diagnosis of chromosomal abnormalities and fetal infections).

I told the doctor when I became pregnant with my daughter that I had a sister who died from muscular atrophy. The doctor told me that the disease was not genetic.

My son could sit by himself when he was 6 months old, but he cannot do so today. We cannot help and his health is declining. He understands that he is disabled.

We do not know when he will leave us, but we try to surround him with happiness. Our family of four has traveled to Yunnan province, Japan and Europe, even though the medicines he requires took up half of our luggage.

I force him to practice moving the wheelchair for an hour each day and now he can move it 10 meters during this time.

I wish he could go to school and that he could be strong enough to hold a pen.

Zhang Ying spoke with Zhou Wenting.