A woman in Scotland can feel virtually no pain due to a mutation in a previously-unidentified gene, FAAH-OUT, according to a new research paper in the British Journal of Anaesthesia.
She also experiences very little anxiety and fear, and may have enhanced wound healing due to the mutation
At age 65, the woman sought treatment for an issue with her hip, which turned out to involve severe joint degeneration despite her experiencing no pain. At age 66, she underwent surgery on her hand, which is normally very painful, and yet she reported no pain after the surgery. Her pain insensitivity was diagnosed by Dr Devjit Srivastava, Consultant in Anaesthesia and Pain Medicine at an NHS hospital in the north of Scotland and co-lead author of the paper.
The woman tells researchers she has never needed painkillers after surgery such as dental procedures.
She was referred to pain geneticists at UCL and the University of Oxford, who conducted genetic analyses and found two notable mutations. One was a microdeletion in a pseudogene, previously only briefly annotated in medical literature, which the researchers have described for the first time and dubbed FAAH-OUT. She also had a mutation in the neighboring gene that controls the FAAH enzyme.
Further tests by collaborators at the University of Calgary, Canada, revealed elevated blood levels of neurotransmitters that are normally degraded by FAAH, further evidence for a loss of FAAH function.
The FAAH gene is well-known to pain researchers, as it is involved in endocannabinoid signalling central to pain sensation, mood and memory. The gene now called FAAH-OUT was previously assumed to be a 'junk' gene that was not functional. The researchers found there was more to it than previously believed, as it likely mediates FAAH expression.
Mice that do not have the FAAH gene have reduced pain sensation, accelerated wound healing, enhanced fear-extinction memory and reduced anxiety.
The woman in Scotland experiences similar traits. She notes that in her lifelong history of cuts and burns (sometimes unnoticed until she can smell burning flesh), the injuries tend to heal very quickly. She is an optimist who was given the lowest score on a common anxiety scale, and reports never panicking even in dangerous situations such as a recent traffic incident. She also reports memory lapses throughout life such as forgetting words or keys, which has previously been associated with enhanced endocannabinoid signaling.
The researchers say that it's possible there are more people with the same mutation, given that this woman was unaware of her condition until her 60s.
The research team is continuing to work with the woman in Scotland, and are conducting further tests in cell samples, in order to better understand the novel pseudogene.