In two subsequent targeted gene studies, the authors investigated the association of VDR gene polymorphisms rs2228570, rs1544410, and rs731236 with cluster headache susceptibility (Papasavva, Vikelis, Siokas, et al., 2022), as well as the HFE H63D variant and cluster headache (Papasavva, Vikelis, Katsarou, et al., 2022), but no associations were found. The gene discussed is HFE; the disease is Cluster headache.