INVOLVEMENT OF CGRP RECEPTOR RAMP1 IN CLUSTER HEADACHE - A SWEDISH CASE-CONTROL STUDY

Background: Increased levels of the potent vasodilator calcitonin gene-related peptide (CGRP) have been found in ipsilateral jugular vein blood during the active phase of cluster headache (CH) and this is hypothesized to cause distinctive vasodilation. The receptor activity-modifying protein 1 (RAMP1) is part of the CGRP receptor complex responsible for ligand binding and specificity and therefore constitutes a promising candidate gene for CH. The aim of this study was to investigate the possible genetic association of RAMP1 with CH in Sweden, with focus on two RAMP1 single nucleotide polymorphisms, rs3754701 and rs7590387, and quantify RAMP1 mRNA expression levels in biological tissue from CH patients and controls. Methods: rs3754701 and rs7590387 were genotyped by quantitative polymerase chain reaction (qPCR) in 542 CH patients and 585 control subjects. RAMP1 mRNA expression was determined by reverse transcription qPCR in tissue from 12 CH patients and 12 controls. Results: We identified a significant difference between the CH patient and control groups for rs3754701 ( p = 0.0088). In addition, RAMP1 mRNA expression was enhanced in primary fibroblasts from CH patients compared to controls ( p = 0.0073). Conclusion: The association between rs3754701 and CH and the enhanced RAMP1 mRNA expression in CH patients support the hypothesis that CGRP and its receptor component RAMP1 are involved in CH pathophysiology.