It should be noted that these two patients had no accompaniment of migrainous features, such as nausea, vomiting, and phonophobia or photophobia, and it has ever been reported that the initial head pain of “ascending CH” had the pain trajectory and pain character same as that of LH [12], thus, the “clustering episodes” style of headache attacks might also be suggestive of CH. This evidence concerns the gene PLOD1 and cyclic hematopoiesis.