In the study reporting 123 common (minor allele frequency (MAF) > 2%) migraine variants, subtype analysis showed that 5 associate specifically with migraine subtypes—3 with MA (in or near CACNA1A, HMOX2 and MPPED2) and 2 with MO (near SPINK2 and FECH)11,13. This evidence concerns the gene HMOX2 and migraine disorder.