Alpha chain of HCG is identical to all except ?

Ans. is 'd' i.e., ACTH Human chorionic gonadotropin (HCG) HCG is a placental hormone. It is synthesized by the syncytiotrophoblasitc cells of the placental villi It is a glycoprotein It is a dimer and has two dissimilar subunits a Subunits b Subunits But only the b subunit of HCG is typically measured as a tumour marker because of specificity of the b subunit The b subunit of HCG has unique sequences that are not shared with other human glycoprotein hormones. It is detected by radioimmunoassay using antibodies to the b chain. HCG is not used as tumour marker because a unit of the FSH, LH and TSH are identical So there can be cross reactivity between a subunits of these hormone. That is why in case of testicular tumours the patients also undergo simultaneous assay of LH to be ceain that the marker detected is b HCG.