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Common Missense Variant of SCN9A Gene Is Associated with Pain Intensity in Patients with Chronic Pain from Disc Herniation

Objective
Lumbar intervertebral disk herniation (LDH) is considered one of the major risk factors for lower back pain, mainly caused by irritation of a spinal nerve or its root. One of the genes related to pain perception is SCN9A, which encodes the voltage gated sodium channel NaV1.7, a key molecule involved in peripheral pain processing. It had been presented before that a common polymorphism within SCN9A (rs6746030: G > A, R1150W) might influence nociception in the general population. Hence, the present study was aimed at investigating the association between SCN9A polymorphism and pain sensitivity.


Methods
Pain intensity was measured by means of the visual analog pain scale (VAS) in 176 Caucasian patients with a history of leg and back pain who had been diagnosed with LDH and underwent lumbar discectomy. SCN9A polymorphism was determined by means of TaqMan assay.


Results
A significantly higher preoperative back pain intensity was observed among rs6746030 A minor allele carriers, compared with GG homozygotes (VAS = 7.5 ± 2.4 vs 6.5 ± 2.7, P = 0.012). Similarly, A allele carriers were characterized by higher values of leg pain prior to surgery (VAS = 7.8 ± 2.3 vs 6.8 ± 2.6, P = 0.013). However, postoperative improvement in pain reduction was similar in both groups.


Conclusions
Our results suggest that the SCN9A rs6746030 polymorphism may be associated with pain intensity in patients suffering from symptomatic disc herniation.