A Tasmanian family are counting their blessings after a successful bone marrow transplant for their one-year-old baby.

Zoe van der Molen was one month old when she was diagnosed with the rare and incurable brain disorder, leukodystrophy.

Her three-year-old sister, Lucy, died from the condition last year.

Zoe has returned home to Launceston after eight months of treatment in Melbourne.

She needed high-dose chemotherapy and a bone marrow transplant.

Her mother Olivia says it has been a difficult time but Zoe is doing well.

"She had a high dose chemotherapy regime that went for 10 days," she said.

"Following that there were a few complications, she got really really sick.

"Then she had the cord blood transplant. It took a while for it to take and then it was just a matter of day-by-day recovery.

"The doctors are really, really happy with how she's going. They keep saying she's such an amazing baby for what she's been through."

Her father Daniel says the treatment should slow the progress of the disease.

"The outcome is still very unknown, she might live until she's 20 or we might get her for the next 10 years," he said.

Zoe will still need treatment interstate twice a year.