IGHG4 and cholesteryl ester measurement: A recent study identified that 12 immunoglobulin-related genes (IGKC, IGHG1, IGHG4, IGLC3, IGHG3, IGLC2, IGHA1, IGKV3-20, IGLC1, IGHG2, JCHAIN, and IGHA2) were upregulated in the CE endometria (38).