Chorionic gonadotrophin subunit alpha (CGA),a member of the glycoprotein hormones subunit alpha family, is also known as glycoprotein hormones alpha chain, choriogonadotropin alpha chain, follicle-stimulating hormone alpha chain (FSH-alpha), luteinizing hormone alpha chain (LSH-alpha) and thyroid-stimulating hormone alpha chain (TSH-alpha). The hormones human chorionic gonadotropin (hCG), luteinizing hormone (LH), follicle-stimulating hormone (FSH), and thyroid-stimulating hormone (TSH) are dimers consisting of alpha and beta subunits that are associated noncovalently. The alpha subunits (CGA) of these four human glycoprotein hormones are nearly identical, however, their beta chains are unique and confer biological specificity.