Effect of pain-related sodium channels SCN9A and SCN10A polymorphisms in migraine chronification.

Objective: Based on the frequency of attacks, migraine is classified into two subtypes: episodic (EM) and chronic (CM). Migraine progression from EM to CM is supposed to be affected by various factors, which is known as "migraine chronification. However, the pathophysiology of migraine chronification is multifactorial and still not fully understood. Ion channels are hypothesized to play a role in migraine pathophysiology and are essential for generating and suppressing action potentials, which lie under the pain and related symptoms. Two sodium channel genes, SCN9A and SCN10A, have been reported to be associated with various pain sensitivities. Studies have shown that patients with EM and CM are more sensitive to chronic pain and that pain sensitivity may be a risk factor for chronification. Thus, the current study aimed to determine whether pain sensitivity-related SCN9A and SCN10A polymorphisms affect the EM-to-CM transition.

Methods: For this purpose, genotyping was performed using TaqMan SNP Assay for the (i) SCN9A rs7595255, rs12622743, and rs11898284, (ii) SCN10A rs6795970, rs6801957 SNPs in Turkish EM and CM patients.

Results: The results showed that SCN9A and SCN10A polymorphisms did not play a role in the development of chronicity. However, the results indicated that the SCN10A rs6795970 polymorphism was associated with osmophobia (p = 0.036).

Conclusion: SCN10A rs6795970 polymorphism may be necessary to predict the EM-to-CM transition and identify therapeutic targets. However, further studies are required to confirm the osmophobia association of the SCN10A rs6795970 polymorphism and to investigate the role of these SNPs in chronification.