Emma Austin appeared to be a 'healthy, bubbly and happy' little girl.

But at the age of two-and-a-half, her mother Kirstie began to fear something was wrong when Emma began struggling to put on her shoes and use cutlery.

Her parents took her to see doctors, who said that her daughter was fine and didn't have any problems.

About six months later, however, and while driving Emma to pre-school, Ms Austin said she heard 'strange mumbling noises' in the back of the car and turned round to find her daughter was having a seizure.

What followed was a panicked trip to the hospital and a battery of genetic tests that diagnosed her with the rare one-in-200,000 condition CLN2 Batten Disease, a form of childhood dementia.

The disease causes children to gradually lose the ability to talk, walk, see and swallow and sufferers usually don't survive more than five years after symptoms develop.

Describing her daughter, Ms Austin — who is from Bridgetown, Texas — told Inside Edition: 'Emma was a healthy, bubbly, energetic, happy little girl. We had no problems, no signs, nothing.

'She started with a speech delay and then a little bit of motor delay. 

'In just six months, it was progressively getting worse and that mom and gut instinct in me was like, somethings wrong.'

In a video on TikTok, the mother also described how her daughter had gradually lost the ability to go to the potty and was having sleep disturbances and sudden rages as she approached her third birthday.

After the seizure in April 2021, Emma was diagnosed with Batten Disease the following month.

Her body lacks the TPP1 gene which is required to make an enzyme that clears waste out of the brain and spinal cord.

This leads to a gradual build-up of waste in cells, like in some Alzheimer's patients, causing patients to suffer a gradual mental decline.

Patients only live for a few years after symptoms begin, but doctors say that if a child develops symptoms around the age of 10 years it is possible for them to live into their early 20s. 

Revealing the diagnosis over a Zoom call, due to the Covid pandemic, doctors said Emma would gradually lose the ability to talk, walk, see and swallow and that there was no cure for the condition.

The family now battles the disease every day, with Ms Austin having quit her job to become her daughter's full-time carer.

Emma is now nearly seven years old and can still walk, run and see and is still able to eat for herself and swallow.

Her parents believe this is thanks to a twice-a-week infusion of the enzyme she is missing to help clear waste.

The enzyme replacement therapy is called Brineura, and is a man-made version of it that is administered directly to the brain.

It was listed as the eighth most expensive drug in the US by GoodRx in 2022, with one dose costing around $35,000.

Although it has improved her condition, Ms Austin said she is still struggling: 'The awareness when we have play dates or she is at a playground and she is around other children, she just stands there by herself and stares.

'And you can see it in her eyes, you can tell she's wondering: "Why can't I do that?".'

Her father Eric added: 'Now that she is getting older, you can see that she sees it — you can see that she recognizes that she is different and all her friends and her cousins have moved on beyond her.

'They are doing things that she can't do and that she knows she can't do, and it is really hard to watch that.'

The family is fundraising to help cover the cost of Emma's medications as well as the home alterations they need to make for her.

This includes the purchase of safety beds, safety chairs, wheelchairs, and a supply of diapers and wipes. 

It has so far raised $20,300 of the $50,000 goal on GoFundMe.

The family believes a cure for Emma's condition may have already been found in Brazil.

The concoction, which can stimulate the body to start making the enzyme Emma is missing, helped a patient during a clinical trial.

But the research was then abandoned because the company felt it could not turn a profit on the medication.

The family are now fundraising alongside the Batten Disease Support and Research Association (BDRSA) to buy the treatment's patent and then develop it.