'We do not know when he will leave us'

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.