Falsely Born into Islam: No Way Out?
An old news story, so perhaps no longer available, but:

A Malaysian Muslim man switched at birth in a hospital mix-up wants to change his name after being reunited with his ethnic-Chinese biological family and become a Buddhist.

I am quite curious as to how this turned out. Is the unlucky soul still alive?

A little on his Muslim upbringing:

As a child, Zulhaidi said, he was teased about his Chinese-like features and never felt accepted by the family in which he was brought up, so he left them when he was 13.

"My Malay father had left us when I was three," he said. "My mother remarried, but I could not get along with my stepfather, so I left."

About "religious freedom" in officially Muslim Malaysia:

Whether Muslims can convert to another faith is a tricky legal question in Malaysia, where Islam is the official religion, although freedom of worship is a constitutional right.