Jo Cameron smells her smouldering flesh before realising she has even been burnt and scoffs down chilli peppers with ease — and now doctors believe the 71-year-old could hold the key to new treatments for chronic injuries, after discovering she feels virtually no pain.

Key points: Jo Cameron was referred to pain geneticists after doctors discovered she underwent serious surgery without painkillers

Jo Cameron was referred to pain geneticists after doctors discovered she underwent serious surgery without painkillers Her genetic mutations suppress pain and anxiety and boost happiness, wound healing and memory loss

Her genetic mutations suppress pain and anxiety and boost happiness, wound healing and memory loss Researchers believe the findings point towards a "novel painkiller discovery"

The former teacher has a rare genetic mutation that means she feels less pain, heals faster and experiences less anxiety than most people.

From broken limbs and cuts to childbirth and surgery, Ms Cameron — who resides in Inverness in northeast Scotland — should be no stranger to discomfort.

But for the first 65 years of her life, she was blissfully unaware of her condition.

It wasn't until she underwent serious surgery on her hand that doctors sensed something was amiss.

"When [the doctor] found I hadn't had any [painkillers], he checked my medical history and found I had never asked for painkillers," Ms Cameron told the BBC.

"If you don't need them you don't question why you don't … you are what you are, until someone points it out.

"I was just a happy soul who didn't realise there was anything different about me."

'It would be nice to have warning'

Ms Cameron was referred to pain geneticists at University College London (UCL), who looked into her DNA to determine what made her so unique.

The results, published in the British Journal of Anaesthesia this month, revealed two mutations that simultaneously suppressed pain and anxiety and encouraged happiness, wound healing and memory loss.

The first mutation lessened the activity of a gene called FAAH, which is central to regulating pain sensation, mood and memory.

The second discovery, however, took researchers by surprise.

The mutation suppresses pain, meaning Ms Cameron never needed to use painkillers. ( Pexels/JESHOOTS, CC0 )

Its been dubbed FAAH-OUT — and while scientists previously thought it was a "junk gene" that was not functional, they now believe it "mediates FAAH expression".

To put it simply, it acts as a volume control on pain, mood and memory.

As part of her mutation, Ms Cameron has a "microdeletion", which prevents that control from working normally.

"She reported numerous burns and cuts without pain, often smelling her burning flesh before noticing any injury, and that these wounds healed quickly with little or no residual scar," the report noted.

"She reported eating Scotch bonnet chilli peppers without any discomfort, but a short-lasting 'pleasant glow' in her mouth.

"She reported long-standing memory lapses … she also reported never panicking, not even in dangerous or fearful situations, such as in a recent road traffic accident."

Researchers believe the mutation may have been passed down from Ms Cameron's father, who himself "had little requirement for pain killers".

Further testing revealed that her son also exhibited some signs of pain insensitivity, though the same traits were not observed in her daughter.

For Ms Cameron, the revelation has been enlightening. While able to reflect on events like childbirth as "quite enjoyable really", she believes her condition means she has missed "alarm bells" along the way.

"It would be nice to have warning when something's wrong," she told the BBC.

"I didn't know my hip was gone until it was really gone, I physically couldn't walk with my arthritis."

What does the discovery mean?

Researchers say the discovery could help shine a light on the role of genetics in pain management — and believe there could be more people out there with the same mutation.

"People with rare insensitivity to pain can be valuable to medical research as we learn how their genetic mutations impact how they experience pain," one of the study's lead researchers, James Cox said in a statement.

James Cox said the findings could contribute to clinical research for post-operative pain and anxiety. ( Supplied: University College London )

"We hope that with time, our findings might contribute to clinical research for post-operative pain and anxiety, and potentially chronic pain, PTSD and wound healing, perhaps involving gene therapy techniques."

Ms Cameron is continuing to work with the research team in order to better understand the pseudogene, including undergoing further tests in cell samples.

"The implications for these findings are immense," said Devjit Srivastava, co-lead author of the paper.

"The findings point towards a novel pain killer discovery that could potentially offer post-surgical pain relief and also accelerate wound healing.

"We hope this could help the 330 million patients who undergo surgery globally every year."