Background: Nitric oxide (NO) is an important autocrine and paracrine signaling molecule that plays a crucial role in cardiovascular physiology and pathology regulation. NO is an important molecule involved in regulation of cerebral and extra cerebral cranial blood flow and arterial diameters. Reduced bioavailability of NO in the endothelium is an important precursor for impaired vasodilation and arterial hypertension (AH). Furthermore, NO is involved in nociceptive processing. A NO-induced biphasic response with immediate and a delayed headache is typical for chronic tension-type headaches (TTH) in humans. The aim was to study the association of allelic variants and genotypes of the single nucleotide variant (SNV) rs3782218 of the NOS1 gene with the TTH and AH overlap syndrome development in middle age adults.
Materials and methods: We observed 91 Caucasian participants who resided in Krasnoyarsk city: group 1 (TTH and AH overlap syndrome)-30 patients; group 2 (AH without headache)-30 patients; group 3 (control)-31 healthy volunteers. The diagnosis of AH was based on criteria of the European Society of Cardiology and the European Society of Hypertension (2018) и criteria of the Russian Society of Cardiology (2020). Diagnosis of TTH was based on criteria of the International Classification of Headache Disorders (2018). Real-time polymerase chain reaction was used for the determination of allelic variants and genotypes of the SNV rs3782218 of the NOS1 gene in all groups of participants.
Results: The frequency of the minor allele T of rs3782218 was statistically significantly higher by 16.7 times in group 1 (TTH and AH) compared to group 3 (control): 26.7% versus 1.6%, respectively (p-value = 0.000065) and 3.2 times higher in group 1 (TTH and AH) compared to group 2 (AH without headache): 26.7% versus 8.3%, respectively (p-value = 0.008). The frequency of the heterozygous (CT) genotype was statistically significantly higher in group 1 (TTH and AH) compared to group 3 (control): 40.0% versus 3.2% (p-value = 0.000454) and in group 1 (TTH and AH) compared to group 2 (AH without headache): 40.0% versus 16.7% (p-value = 0.045). The minor allele T was statistically significantly associated with a high risk of developing the TTH and AH overlap syndrome compared with the controls (odds ratio (OR) = 22.2 (95% confidential interval (CI): 2.8-173.5)) and compared with AH without headache (OR = 4.0 (95% CI: 1.4-11.8)). Although the frequency of the minor allele T was 5.2 times higher in group 2 (AH without headache) compared with group 3 (control), there were not statistically significantly differences (p-value = 0.086).
Conclusion: Thus, the minor allele T of rs3782218 of the NOS1 gene is an important genetic biomarker for a high risk of developing the TTH and AH overlap syndrome in hypertensive patients.
Keywords: NOS1; arterial hypertension; comorbidity; genetic biomarker; nitric oxide; overlap syndrome; rs3782218; tension-type headache.