When his 18-year-old son met with a road accident in the United States in 1983 and went into a coma, American doctors advised Dr Tan (not his real name) to 'let your son go'.

After all, the young man had permanent brain damage and could survive only as a human vegetable, they said.

As a medical doctor, he knew what that meant. But as a father, he could not bring himself to pull the plug.

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