A Scottish woman goes through dental treatments, childbirth and hip surgery – needing only a very low dose of painkillers. She only notices skin burns once she smells charred flesh; her family makes her aware that she has cut wounds. How can this happen?
For almost four years, the 65-year-old Scot has not been very mobile. She often seeks help from her family doctor. Yet the patient is pain-free, her complaints are not considered serious. Only when she cannot walk any more does the doctor look more closely – and he is astonished when he notices in X-ray images severe degeneration of the joints. Her osteoarthritis has progressed so far that the woman has to undergo hip surgery.
Painkiller? No thanks
The procedure goes well, the implant of the new hip is a problem-free success. Following that, the patient baffles her doctors again: she does not need any pain killers. She recovers very quickly and is released. Less than a year later she needs to undergo surgery again, this time on her hand. Many sufferers find such procedures very painful, but here as well the Scottish woman does not need painkillers after surgery. Her anaesthetist, Dr Devjit Srivastava, is awake to the matter and refers her to pain experts at University College London and Oxford University.
Research in Scotland, England and Canada
By conducting an on-site gene analysis, biologists find two striking mutations associated with fatty acid amide hydrolase (FAAH). One is a pseudogene microdeletion which had been undescribed until now. The doctors have named it FAAH-OUT. The other mutation is found by the researchers to be in a neighbouring gene which controls the FAAH enzyme. The woman travels to Canada for further tests and is examined at the University of Calgary.
There the researchers' suspicions are confirmed. Blood tests show that the patient has an elevated level of neurotransmitters in the blood – these are normally reduced by FAAH. FAAH function in her body is obviously limited. Pain experts know this function well: it is involved in the endogenous cannabinoid system and is important for pain sensations, mood and memory functions. Rats and mice lack the enzyme, which leads to reduced pain sensation, accelerated wound healing, and decreased anxiety.
Presumed junk gene with great impact
The previously recognised, but never named, FAAH-OUT had been treated as a sort of junk-DNA gene without a function. But in the Scottish woman it apparently has similar effects to those in the small rodents. In her medical interview, she recalls never needing painkillers and often not even noticing cut wounds. Whenever the woman, a vegan, suffered burns, she often only noticed them when she detected the smell of burned flesh. And in a serious car accident, in which she was involved and survived unhurt, she had been very calm, whereas the other driver was shaking all over.
Even after dental treatment or when giving birth, the woman has never needed painkillers. Looking back, she describes the birthing process as pleasant and painless. Her daughter has inherited none of the extremely rare mutations. Her son, however, also has reduced pain perception. Specialists hope that by publishing their results, more of those people who carry similar mutations – and had simply put their experiences down to luck, as did the now 71-year-old Scot – can be found. Advanced research on analgesics and anxiolytic drugs, and in the treatment of post-traumatic stress disorder (PTSD), could benefit significantly, according to the biologists.
Sources: British Journal of Anaesthesia, Science Daily
Image Source: Molly Belle, Unsplash