Objective: To screening mutations of exons 15, 18 and 26 of sodium channel Nav1.7 (SCN9A) gene, and to assess its association with pain related to Parkinsonism.
Methods: Respectively, 101 patients with primary Parkinson's disease (PD) and 104 similar-aged volunteers without PD were recruited from March, 2008 to January, 2011. Mutations of above 3 exons in SCN9A gene was detected with PCR and direct sequencing. For 100 patients with Parkinsonism, the pain was scored with a McGill pain rating scale. Statistical analysis was performed with SPSS.
Results: The prevalence of pain in Parkinsonian was 57%. 43.86% patients with pain were males, and 56.14% were females. Based on Chaudhuri criteria, the pain symptoms may be classified as musculoskeletal pain (10.52%), radicular pain (10.52%), dyskinesis pain (54.38%), pain from akathisia and restlessness (14.04%), dyskinesis combined with radicular pain (5.26%), skeletal muscles pain and headache (1.75%), and arthralgia (3.50%). Two missense mutations were identified, which included 2794A/C (0.941/0.059) (rs12478318) (M932L) in exon 15 and 3448C/T (0.988/0.012) (rs6746030) (R1150W) in exon 18. The wild type A/C for the 2794 locus had a higher prevalence in PD patients with pain, but this was not statistically different. All of the 5 heterozygotes for 3448 (C/T) were found in Parkinsonian patients with pain. No homozygotes were found.
Conclusion: The prevalence of pain was higher in Parkinsonian patients than general population, and the proportion of males to females was similar. More patients have suffered dyskinesis pain. A 3448 (C/T) mutation of SCN9A gene may be related to pathogenesis of pain in Parkinsonism.