GDF15 and migraine disorder: Increased genetic risk for migraine was correlated with genetic factors for increased levels of six blood proteins (Fig. 2a), including matrix metallopeptidase 7 (MMP7, r = 0.0141, P = 2 × 10–6), CUB and zona pellucida like domains 1 (CUZD1, r = 0.0114, P = 1 × 10–4), KIT ligand (KITLG, r = 0.0094, P = 2 × 10–3), vascular endothelial growth factor A (VEGFA, r = 0.0090, P = 3 × 10–3), haemoglobin subunit theta 1 (HBQ1, r = 0.0089, P = 3 × 10–3), and growth differentiation factor 15 (GDF15, r = 0.0087, P = 4 × 10–3).