An extensive meta-analysis of data from the UK Biobank has found a different genetic basis for chronic pain in women compared to men.
The results are still preliminary, but so far, this is one of the largest genetic studies on chronic pain to analyze female and male separately.
“Our study highlights the importance of considering sex as a biological variable and showed subtle but interesting sexual differences in chronic pain genetics,” says population geneticist Keira Johnston of the University of Glasgow in Scotland.
Chronic pain conditions are among the most common, disabling, and costly conditions in public health. In the United States, chronic pain affects more people than heart disease, diabetes, and cancer combined, but it receives a fraction of global funding.
Even when studies are done, the underlying sexual differences are often overlooked, and this is a huge and detrimental oversight. Compared to men, women are much more likely to develop multiple chronic pain disorders, and yet historically, 80 percent of all pain studies have been conducted in mice or human humans. This means that we know very little about how and why women suffer more and what treatments can help them better.
Although there are likely to be multiple biological and psychosocial processes in this sexual discrepancy, current genome-wide study suggests that there is also a genetic factor in the mix.
Comparing genetic variants associated with chronic pain in 209,093 women and 178,556 men at the UK Biobank, researchers have tried to find at least part of the answer to our biology.
In the end, the researchers found 31 genes associated with chronic pain in women and 37 genes associated with chronic pain in men with virtually no overlap. The authors admit that some of the differences here may be derived from the size of the lowest male sample, but the results are fascinating.
When the researchers tested the expression of all these genetic variants in various tissues of mice and humans, they observed that the vast majority were active in a cluster of spinal cord nerves, known as the dorsal root ganglion. , which transmits messages from the body to the brain.
Several genes on the exclusively male or female list were associated with psychiatric problems or immune function, but there was only one gene, known as DCC, in both lists.
DCC encodes a receptor that binds to a protein crucial for the development of the nervous system, especially the dopaminergic system; In addition to being a reward center, the latter has recently been linked to pain modulation in the body.
DCC is also believed to be a risk gene for the pathology of depression, and DCC mutations appear in those with congenital mirror movement disorder, which results in the reproduction of movements from one side of the body to the other. ‘other side.
It is not yet clear exactly how DCC relates to chronic pain, but the authors claim that its results support several theories “of the strong nervous system and immune involvement in chronic pain in both sexes,” which they hope will be ‘use to develop better treatments in the future.
If chronic pain is most strongly associated with immune function in women, for example, the side effects of drugs aimed at immunity may be very different from men. On the other hand, treatments such as chronic opioid use can also have different outcomes. Opioids are known to negatively affect immune function, suggesting that they could make things worse and not improve them for women with chronic pain.
For now, at least, they are just ideas. More research needs to be done on pain and much more needs to be done among women before we can begin to understand the real sexual discrepancies at stake and what we can do about it.
“All of these lines of evidence, together, suggest supposed central and peripheral neural roles for some of these genes, many of which have historically not been well studied in the field of chronic pain,” the authors conclude.
The study was published in PLOS Genetics.