RTN4R and migraine disorder: We looked at the frequency of 15 SNPs from five genes primarily associated with Nogo-type signaling; the ligands RTN4, OMGP and MAG, the key receptor RTN4R, and the co-receptor LINGO1. The most recent GWAS of migraine identified 38 suspected loci [20], none of them a part of Nogo-type signaling.