She may also be the oldest person in the world with Tay Sachs disease, a degenerative neurological condition that affects the central nervous system.

It causes blindness, paralysis, seizures, and the child usually dies before the age of five.

Tuesday is Elsie’s fifth birthday, and it is a milestone mum Michelle Towers never expected the family would reach.

“She wasn’t expected to make it to five,” Ms Towers said.

“We were told we wouldn’t have her when she was three, so she’s done really well and she’s fighting it against the odds.”

“She’s doing quite well to be here with us today. She has a diagnosis of Tay Sachs disease and she’s enjoying it to the best of her ability.”

Tay Sachs is an extremely rare genetic condition, with a one in 460,000 chance of someone being born with it.

There are thought to be only two children in  Australia with the condition. Elsie suffers from constant infections and seizures, and needs to be fed through a gastronomy tube.

But even with her diagnosis, Elsie is like any other child her age, including laughing when her brother gets into trouble, Ms Towers said.

“She’s got a wicked sense of humour. I’ve got a six-year-old [Toby] who sometimes gets in trouble and ever since she was born, even though she couldn’t do much, she used to laugh every time he got in trouble and to this day she still does,” Ms Towers said.

“She loves music, she loves to be surrounded by people she loves and kids - she loves kids.”

Elsie celebrated her birthday at the weekend with a party at the Secret Garden cafe, and loved being surrounded by friends, music and laughter.

“She is loving having all the kids around her, all the noises,” Ms Towers said.

“She doesn’t have a lot of eyesight so she is enjoying all that sensory stimulation. She’s having a look around and doing what she can with all the kids.”

“I think she had a lovely day, it’s a beautiful spot here for the kids to run around and lots of people. It’s very special, she’s surrounded by a lot of love.”

The party was also a nice way to thank the people of Wongarbon, where the family live, and Dubbo for all of their support.

“We have a lot of special people,” Ms Towers said.

“We’ve had a lot of feedback and a lot of support. We live in Wongarbon and everyone in the community is really helpful. My son goes to school there and even the school rallies behind us and supports us, supports Toby because they know our situation and they also include Elsie in anything that happens in the community.”

“We’ve always just tried to give Elsie the best life we can based on her skills and what she can do, and her strengths. We just take everyday as it comes and we just make it the happiest we can.”