The parents of Liam Heffernan say their son's seizures have increased and he has gone blind.
Liam, who has just celebrated his fifth birthday, lost his older sister Saoirse to the same disease - Battens - in 2010 when she was his age.
Now his parents - Tony and Mary Heffernan - are concentrating on giving their son the best quality of life available.
They have been told their son will more than likely pass away in the next twelve months.
In the last year, Liam has gone blind, lost nearly all mobility and has not be able to consume solid foods.
“It’s not easy, there are no resources," Tony said.
"At the moment, we don’t get much assistance. You keep asking and asking, and hoping something will happen, but that’s life. His lifespan is less than 12 months to live, apparently. His sister died at five and a half and he turned five on July 3rd."
Mr Heffernan splits his time between here and Oslo, where he is based with work.
“It’s a difficult period," he added.
"He’s going through a huge increase in seizure activity, but he’s coping reasonably well with going blind and losing his mobility. Then, there’s the emotional frustration as well.
“Children tend to learn things and improve all the time. However, children with Battens disease don’t.
"As the disease progresses, it removes those bit by bit. It takes away every single function eventually.
"Liam hasn’t eaten solid food for over a year, he’s on a liquid insertion. Soon, he’ll get a peg insertion in his stomach so that he can be fed through that.”
The Heffernans treasure each moment with their young son, who was once an active, 'average' little boy.
“You just try to hold yourself steady, my wife and I have a very strong relationship," Tony said.
"We try to give him the best quality of life. Liam’s needs are significant. One of us has to stay with him overnight. He wakes up on several occasions and you can’t leave him out of your sight for a second. He requires constant 24-hour care."
Tony added that he is determined to transform his own lifestyle into a healthier one in order to give Liam the best possible care.
“Myself and my wife recently ran a 10k, just to raise awareness under The Saoirse Foundation in Killarney.
"I’m a fairly large individual - well I still am and I had to lose two stone to get ready for the 10k. It’s all about getting yourself healthier and being able to provide the best quality of care for Liam."
Tony and Mary Heffernan are vocal campaigners for Batten's disease awareness, which is one of the rarest conditions in the world.
The couple also run the Saoirse Foundation, supporting other Irish families in similar positions.
And little Liam is the inspiration behind 'Liam's Lodge' - Ireland's first respite centre for children with rare diseases and genetic conditions.
The project is now underway.
It is hoped that Liam's Lodge will welcome it's first family in 2015, initially catering for 520 families each year, and increasing to 1,560 when built.
Visit www.liamslodge.com for more information.