A family from Wigan are desperately trying to raise £70,000 to get their six-year-old daughter life-saving treatment abroad.
Hallie Campbell was born with a rare genetic condition called AADCd (aromatic amino acid debarboylase enzyme deficiency).
It is so rare that Hallie is the only girl in the UK to have ever been diagnosed with the condition.
A hospital in Poland has offered her gene therapy but because the treatment is still being trialled, the NHS won't pay the £70,000 that it will cost.
The family have now launched a fundraising appeal to raise the money themselves.
Our Correspondent Mel Barham has this report: