A MELBOURNE baby given no chance of survival has amazed doctors after being saved with one of the biggest long shots in medical history.

"Baby Z's" brain started virtually dissolving soon after she was born 18 months ago because she had too much toxic sulphite in her system.

But her parents and doctors refused to give in to the one-in-a-million genetic condition and stumbled on a highly experimental drug. The Herald Sun can reveal treatment began a month after she was born and within days Baby Z "woke up".

"It was really like awakening - it was just bang, and she was switched on," pioneering neonatologist Dr Alex Veldman said.

Baby Z's overjoyed mother said she had grown into a happy and determined little girl.

"She is absolutely delightful and as stubborn as anything - I don't know where she gets that from," she said. "She has just started saying a few words and is constantly moving around.

"Every day just gets better and better. We look at her every day and just think, 'Wow'."

The first person to be cured of molybdenum cofactor deficiency - a condition that poisons the brain and kills within months of birth - Baby Z has made world medical and legal history for Monash Children's at Southern Health.

The child and her parents cannot be named for legal reasons and to protect their privacy.

But her relieved mother told the Herald Sun she refused to accept her daughter would die, even when told she had no chance.

"(The procedure) was a tiny bit of hope but, when you have nothing, that is a lot of hope. She might have one bad gene but she has a lot of other good and strong genes."

Soon after she was born in 2008, Baby Z's toxic sulphite levels were almost 30 times higher than normal and were dissolving her brain.

After three weeks looking for answers, biochemist Dr Rob Gianello found a research paper by German plant biologist Prof Gunther Schwarz describing how he had developed an experimental drug that was able to save mice with the disease in 2004.

The drug had hardly been used in animals and nobody had more than an educated guess at what it would do in a human.

But Monash's Dr Alex Veldman contacted Prof Schwarz in Cologne and appealed to the hospital's ethics committee to use the drug on Baby Z. The long shot was backed because the only other option was a painful death.

The Office of the Public Advocate then called on special medical procedure powers - used just twice before - to convince the Family Court to allow the unique treatment to go ahead. Within an hour of the court's approval, Baby Z was given the drug.

Within hours of receiving her first daily dose of cPMP (cyclic pyranopterin monophosphate), tests showed Baby Z's sulphite levels immediately dropped from near 300 to below 100. Within three days they fell to the normal level of about 10.

Baby Z's neurological development is delayed due to some brain damage in the weeks it took to find the cure, but she is now improving.

The full details of the treatment are now being analysed for a planned human trial of the medication at Southern Health.

Victorian Public Advocate Colleen Pearce said she was thrilled everything had fallen into place for Baby Z and her family.

Originally published as Baby saved in medical miracle