Genetic testing eventually revealed not only did Oscar have the extremely rare dyskeratosis congenita, but so did his mother Michelle Corcoran, older brother Nathan and sister Heidi.

Ms Corcoran’s mother and brother were also tested after Oscar’s diagnosis.

Oscar’s family and a five-year-old Sydney boy are the only known Australian sufferers of dyskeratosis congenita, which affects just one in a million people worldwide. 

There are only 149 families affected across the globe.

Oscar’s father Grant and his eldest son Justin don’t have the disease, which has no cure or treatment, though bone marrow transplants can be a risky

option.

“People don’t know how bad or how quickly it will evolve,” Mr Possingham said.

“It’s very hard to know your kids will only get worse.”

He said the illness basically aged sufferers prematurely but on the inside, not externally.

Obvious symptoms include abnormally shaped nails and teeth, skin pigmentation, narrow tear ducts, hair loss or prematurely greying hair and white patches inside the mouth.

Sufferers have an increased risk of developing life-threatening conditions, particularly bone marrow-related ones such as aplastic anaemia, leukaemia and certain cancers.

They can also develop pulmonary fibrosis, which causes scar tissue build-up in the lungs, hip and shoulder joint degeneration and liver disease.

With Mr Possingham the family’s full-time carer, a fund-raiser is being held next month to send Ms Corcoran, Justin and Nathan to a special American camp in October.

Camp Sunshine will include other dyskeratosis congenita sufferers and their families, along with medical specialists.

Funds raised will also go towards the family’s medical costs, mainly transport and accommodation for regular Royal Children’s Hospital visits.

A quiz night will be held at the Learmonth Football Club on Friday, September 19, at 7pm. 

Tickets for $20 each can be bought from the Stag Hotel, Learmonth, through the family’s Our Rare Kids Facebook page or on 0439 559 448.

Any businesses wishing to donate goods for the night can also contact the mobile number or drop items at the Stag Hotel.

The family, which is heavily involved with the Learmonth Football Netball Club, has also been given permission to tin rattle at this year’s CHFL grand final.

fiona.henderson@fairfaxmedia.com.au