KIR3DL2 and endometriosis: Considering the other NK cell regulatory genes that were significantly altered in the majority of the endometriosis datasets (4–6/6), either a particular receptor (e.g. KIR3DL2) or the ligand (e.g. NECL2) was differentially expressed, but paired alteration of both the receptor and its ligand was not observed (Additional file 2: Table S1).