The next year could be crucial in a five-year-old’s battle with a rare form of childhood dementia, his mother believes.

Tammy McDaid, from Swansea, said that instead of waking up excited to celebrate Tate’s birthday, she had a panic attack because she knows the clock is ticking for him.

He has Sanfilippo Syndrome – a form of dementia that just over 100 UK children have, and which can progress more rapidly after the age of five.

The family are pinning their hopes on a new drug that could be approved for use in the US later this year, allowing Tait to potentially start treatment in the summer, slowing the progress of the disease.

“I woke up and had a panic attack that morning because the next 365 days can be crucial because of what he has got,” said Tammy, 34, of her son’s birthday.

One of the hardest things to come to terms with would be when Tate’s condition began to impact on his mobility, she added.

If approved by the US Food and Drug Administration, the drug could delay the onset, and allow Tate to remain active for longer.

Describing him as her “handsome little man”, Tammy added: “I know it isn’t a cure but it will give him a significantly better quality of life.”

There is currently no cure for Sanfilippo Syndrome Type A, also called Mucopolysaccharidosis type III (MPS III).

But the drug which Tammy hopes her son can access could delay the onset of symptoms.

The condition, described as “childhood Alzheimer’s” or “childhood dementia” due to its neurodegenerative nature, causes the gradual loss of abilities, such as walking and eating.

The Society for Mucopolysaccharide Diseases (MPS Society), a charity which helps children living with Sanfilippo Syndrome, said about 140 children in the UK have the condition.

Tammy was told about the potential new UX111 drug, which would be administered by injection, by the Cure Sanfilippo Foundation.

She has raised £35,000 to help cover the costs of accessing a clinical trial, but she needs to raise even more as it would involve staying in the US for a year for monitoring.

“I know it’s going to be in the hundreds of thousands if we go out there for one injection and then monitoring for a year,” she said.

“We’ll get there.”

Tammy said she was also focusing on “living in the moment” and making precious memories with her son.

This included taking Tate on holiday to Fuerteventura in the Canary Islands to celebrate both of their birthdays – which are two days apart – in November.

She said her son is “such a water baby” and he loved spending time in the swimming pool, as well as visiting a water park.

“It was nice to get away and to forget reality,” she said.

“He’s such a happy kid and I really enjoyed us being in our bubble for a week.”

They are also hoping to visit family in Germany in March.

“I am trying to take him to visit as many countries as possible over the next year or two now and to see how many fridge magnets we can get from different countries,” Tammy said.

She said Tate is a joy to be around and it was “amazing he is doing things of his own accord” and learning new skills such as taking his plate into the kitchen after finishing a meal.

“One day, I got through the door, bags in hand, and by the time I came into the living room he had already taken his shoes off and put his socks in the washing machine and my heart melted,” his mum said.

He also started full-time school in September, and is interacting and playing with others.

“I need to live in the moment while he’s learning and is still progressing and he is a happy and healthy little man,” Tammy said.

She has been touched by the support shown by many people, including offers to raise money.

Tammy said Tate’s school were “really supportive and they couldn’t do any more for him”.

There was also a “really positive” meeting with staff at Noah’s Ark Children’s Hospital in Cardiff.

Tammy hopes Tate can undergo intensive speech and language therapy to use a device enabling him to communicate, as he is non-verbal.

By speaking out about her son’s condition, she also wants to raise awareness of childhood dementia.