Then on their death in July 2017, they left behind a surprise bequest: $10 million for medical research at the Australian National University, the largest endowment in the university's history.

No one in their extended family had realised the wealth of the couple known for their humility - $12 million was also set aside for the University of Sydney's Wesley College and hockey club, where Mr Pryor played in between a career as an architect.

Nephew James Graham said the couple were devoted to each other and had worked hard to generate a lasting legacy before they both fell ill.

At the ANU, that legacy could include finding a cure for a rare autoimmune disease known as dermatomyositis (or DM).

Mrs Pryor was diagnosed in her final years with the often debilitating condition, which causes chronic muscle inflammation, pain and weakness.

She bore it largely without complaint, Mr Graham said, as her husband battled motor neuron disease.

Now a research fellowship into the disease at the ANU Centre for Personalised Immunology will bear the Pryor name.

Centre co-director Carola Vinuesa said that, while rare diseases didn't often attract big money, this donation could unlock new treatments and build the world's most comprehensive DM research program ever.

"This changes everything," Professor Vinuesa said.

"We still don't have effective therapies because we don't really understand autoimmune diseases."

While the donation came as a "complete shock", the couple had visited the centre once before. A collaboration with ACT Health, it offers precision treatments where research and medicine collide through gene editing.

"We begin with the patient and we tailor the treatment to their particular genetic mutation we think is behind the disease," Professor Vinuesa said.

"We can then use the technology to replicate those mutations and test them against [therapies]."

The centre has already sequenced the genomes of more than 2000 people, but more people with DM will be needed as the research takes off.

Canberra student Mike was diagnosed with juvenile DM at just four years old. Now 21, he undergoes treatment every month.

While the therapy has greatly reduced his symptoms, it is also time-consuming - and knocks him out with headaches for several days.

"It's difficult, I missed a lot of school but I'm studying now full-time," Mike said.

"I'm quite lucky, I haven't gone into remission like a lot of people who get the disease young but it's not having too big an impact on my life."

Professor Vinuesa said the new funding would offer the strongest chance yet at finding a cure for both DM and its juvenile form.

"We hope to do clinical trials soon," she said.

"We've sort of been pioneers here in Australia for tailored genomic medicine and research, people are now realising it's the future of medicine. We're determined to make a difference [with] this money."

Vice-chancellor Brian Schmidt said the ANU was humbled by the "quiet generosity" of the Pryors, and their faith in the university.

"Great breakthroughs are founded in great research," Professor Schmidt said. "And great research is boosted by generous donations like this.

"People who they have never met, and will never meet, will benefit."

The Canberra Times