A New Brunswick baby is coming home for the first time in 15 months after she was treated in American hospitals for a rare genetic immune deficiency syndrome.

Katlyn Demerchant was born with adenosine deaminase severe combined immunodeficiency [ADA SCID], sometimes referred to a "bubble boy" syndrome.

The 18-month-old toddler has spent much of her life in a hospital room at the National Institute of Health in Maryland undergoing gene therapy.

Katlyn's doctors have decided that her health has improved enough that she can return to her home in Centreville.

"We've always been on this roller-coaster, you know," said Daisy Gallant, Katlyn's mother. "I think that after 15 months, you kind of try your best not to get your hopes up about things so I don't think the excitement's really going to hit us until we're on the road and headed towards New Brunswick."

Katlyn's return, expected by Friday, will mean drinking water in the family home will be boiled. A small amount of bleach will be put in her bath water. Carpets are also being ripped up and replaced with laminate flooring.

Gallant said Monday she expects the little girl to be surprised to have her own room and her own bed at home for Christmas, too.

"I think she'll be excited. When she gets there I imagine we'll hear her saying 'Whoa,' things like that because this is all going to be new to her."

The whole experience has reminded the family of the importance of being healthy and together, Gallant said.