"His ability to crawl or walk was stolen from Heath the day he was born," his mum Anna Sutherland said of his condition, Spinal muscular atrophy (SMA).
"Slowly SMA will rob Heath of every physical ability he has. From holding his water bottle to cuddling his teddy. Eating, drinking, talking, smiling and eventually his ability to breath unassisted will all be stolen away from him."
The condition means the brave toddler faces becoming "trapped in his own body".
"Heath has spent his short, almost three years of life, fighting spinal muscular atrophy [SMA] …," Sutherland, of Rotorua, wrote on crowdfunding site Givealittle.
Heath's family is appealing for help to pay for a medicine that could halt the effects of the type 1 SMA diagnosed when he was 15-months-old.
SMA is a rare genetic disorder that causes a shortage of a protein called SMN, resulting in loss of motor nerve cells and progressive muscle wasting.
Sutherland has told the Rotorua Post that around 80 per cent of children with type 1 SMA die before their fourth birthday.
The SMA medicine Spinraza is government-funded in Australia but not New Zealand.
The Pukekohe family of toddler Charlotte Bond, who has SMA, organised a petition to Parliament, signed by more than 12,000 people, supporting state funding of Spinraza.
The drug causes the body to produce more SMN protein. It isn't a cure, but has been shown to slow or stop the effects of the disease.
Sutherland said, "Spinraza has been proven to stop the disease in its tracks and give the sufferer the strength and abilities they had never had. The younger a person receives treatment the more responsive their body will be. Every day without Spinraza motor neurons are dying, irreversible damage is being done."
In his first year on the drug, Heath would need six doses, given as injections in the lower back, each costing $110,000 - a total of $660,000 for the year.
"We are trying to fund treatment for Heath for one year while we continue to fight our system to value all SMA fighters here in New Zealand and publicly fund Spinraza," Sutherland said.
"Please, please help us save Heath and give him a better quality of life."
"This treatment is the only chance he has at a better, longer life. He's never been able to crawl or walk - at almost three years old his knees are already starting to lock in place and both hips are out of joint due to lack of weight bearing.
"Heath's mind and personality is 100 per cent unaffected. He will one day be trapped in his body. The treatment, Spinraza, will change it all!!!" Sutherland wrote on her crowdfunding page.
Pharmac, the Government's medicine-buying agency, evaluated an application for Spinraza funding last year.
Its pharmacology and therapeutics advisory committee supported deferring a decision until studies on the longer-term benefits for patients on Spinraza, also called nusinersen, were published.
Committee minutes said the reported short-term outcomes were promising, "however, the outcome of sustained preservation of function and motor milestones needs to be demonstrated in long-term data to inform a recommendation".
"The committee noted the high health need of patients and families living with SMA and the high level of consumer interest in nusinersen.
"Members acknowledged the many personal submissions that were considered by the [rare disorders] subcommittee describing the impact of SMA. The committee considered that the expectations of benefit are not supported by the currently available evidence for nusinersen in SMA due to the short-term duration of the clinical trials."
