Hot Topics in Life Sciences: Genetic Variability, Pain and Disability
Most pain states are temporary, i.e. the pain intensity is reduced along with the healing process. For some patients, however, pain persists and may become chronic. Such persistent pain conditions are often associated with a prolonged inflammatory process, which in turn may be related to functional cellular changes in the pain pathways.
Earlier studies show that tissue damage associated with long-lasting inflammation enhances the neuronal activity in the sensory system. For example previous findings show that intervertebral disc herniation, and subsequent leakage of nucleus pulposus (NP) out of the disc, increases the excitability of the primary afferent nerve roots and dorsal horn neurons. NP induces inflammatory and immunological responses that involve interleukin-1 (IL-1) and human leukocyte antigen II (HLA II). In addition, the mu-opioid receptor 1 (OPRM1) and the enzyme Catechol-O-metyltransferase (COMT) in the brain may be important for the supraspinal nociceptive modulation.
We all carry the same genes, but the exact DNA code may vary between individuals that affects a number of physiological processes. Hence, genetic variability may also be important for pain. The present lecture emphasizes that genetic variability may affect both the local inflammatory and immunological responses following disc herniation mentioned above, as well as the supraspinal nociceptive modulation. Better understanding of the mechanisms underlying these neurobiological features may be important for future management of persistent pain conditions.
 Moen A, Schistad EI, Rygh LJ, Roe C, Gjerstad J. Role of IL1A rs1800587, IL1B rs1143627 and IL1RN rs2234677 genotype regarding development of chronic lumbar radicular pain; a prospective one-year study. PLoS One. 2014;9(9):e107301.
 Dominguez CA, Kalliomaki M, Gunnarsson U, Moen A, Sandblom G, Kockum I et al. The DQB1 *03:02 HLA haplotype is associated with increased risk of chronic pain after inguinal hernia surgery and lumbar disc herniation. Pain. 2013;154(3):427 – 33.
 Olsen MB, Jacobsen LM, Schistad EI, Pedersen LM, Rygh LJ, Roe C et al. Pain intensity the first year after lumbar disc herniation is associated with the A118G polymorphism in the opioid receptor mu 1 gene: evidence of a sex and genotype interaction. The Journal of Neuroscience. 2012;32(29):9831 – 4.
 Jacobsen LM, Schistad EI, Storesund A, Pedersen LM, Rygh LJ, Roe C et al. The COMT rs4680 Met allele contributes to long-lasting low back pain, sciatica and disability after lumbar disc herniation. European journal of pain. 2012;16(7):1064 – 9.