What is "Neuropathic Pain" and is it genetic?
While your environment does play a role in developing this chronic nerve condition, new research suggests a surprising genetic link.
Neuropathic pain (or NP) is a type of chronic pain in the nerves. It can feel like a burning or stabbing sensation or sharp and sudden like an electric shock. NP can also make your skin sensitive to the touch or to other sensations like cold. It's painful to live with and very uncomfortable.
Neuropathic pain is a consequence of damage or injury to the nerves. In particular, NP is caused by damage to the nerves responsible for transferring information between the brain and spinal cord from the skin, muscles, and other parts of the body.
Common risk factors for neuropathic pain include advancing age, female sex, smoking, high body mass index (BMI), poor general health, and low socioeconomic status. NP is a serious health problem for many Americans. In fact, researchers estimate that as many as 1 out of 10 Americans over 30 experience neuropathic pain (with estimates ranging from 7-10% of the U.S. adult population).1 Meaning NP could be an issue for anyone over 30!
However, the factors listed above don't fully explain the risk of developing neuropathic pain. Scientists now believe genetic factors can also play a role in your risk of developing this debilitating condition.
Neuropathic pain -- the genetic connection
A recent twins study from the United Kingdom revealed the major role genes can play in developing neuropathic pain. By comparing identical and fraternal twins, the authors hoped to determine whether nature (genes) or nurture (environment) plays a bigger role in determining NP. They do this by determining something called heritability. Heritability simply measures what percentage of the variability of a trait in a population is due to genetic differences. In this case, the UK researchers estimate a heritability of 37% for neuropathic pain.
However, while several candidate gene association studies have reported associations of genetic variations with NP, these studies lack consistent replication (aka continuous results). And only 3 genome-wide association studies (called GWASs) have been published, and they identified no genome-wide significant variants. In other words, we haven't proven which genes are associated with NP with any certainty.
But...
Recently, researchers conducted a large meta-analysis (meaning a data analysis of multiple studies) to identify the underlying genetic influence on neuropathic pain susceptibility.* Individuals with neuropathic pain** and individuals with no pain (control participants) with or without diabetes were identified using validated self-completed questionnaires. The meta-analysis of this data yielded a novel genome-wide significant variant for the first time. The CAB39L gene was significantly expressed in the tissues relevant to neuropathic pain generation, including spinal nerve bundles and the brain cortex.***
Researchers also found a weak association with pain-related traits, including disc problems and fibromyalgia. They also found the suggestive variant was associated with lower limb ulcer and neck/shoulder pain. While these associations are interesting, they need to be confirmed by independent data sets.
To learn more, check out the study HERE. And if you'd like to learn about your own genetic risk factors for neuropathic pain, log-in to your Genomelink Traits to see this genetic trait.
* Study participants came from the Genetics of Diabetes Audit and Research in Tayside, Scotland (GoDARTS), Generation Scotland: Scottish Family Health Study (GS:SFHS), and the United Kingdom Biobank (UKBB).
** This refers to case participants: those with pain of 3 months' duration.
*** In addition, rs77526294, rs7336018 in the CAB39L gene, rs34932751 in the SLC17A4, and rs4688956 were associated with NP with suggestive significance.
1 Yawn BP, Wollan PC, Weingarten TN, Watson JC, Hooten WM, Melton LJ 3rd. The prevalence of neuropathic pain: clinical evaluation compared with screening tools in a community population [published correction appears in Pain Med. 2011 Aug;12(8):1294]. Pain Med. 2009;10(3):586-593. doi:10.1111/j.1526-4637.2009.00588.x
