activ ation ▁and ▁it ▁takes ▁the ▁advantage ▁of ▁having ▁different ▁m eth yl ation ▁status ▁of ▁a ▁gene ▁called ▁H U MA RA ▁( short ▁for ▁Human ▁And ro gen ▁re ceptor ) ▁that ▁is ▁located ▁on ▁X ▁chrom os ome . ▁Consider ing ▁the ▁fact ▁that ▁once ▁one ▁X ▁chrom os ome ▁is ▁in activ ated ▁in ▁a ▁cell , ▁all ▁other ▁cells ▁derived ▁from ▁it ▁will ▁have ▁the ▁same ▁X ▁chrom os ome ▁in activ ated , ▁this ▁approach ▁becomes ▁a ▁great ▁tool ▁to ▁differenti ate ▁a ▁mon oc l onal ▁population ▁from ▁a ▁poly cl onal ▁ ▁one ▁in ▁a ▁female ▁t issue . ▁H U MA RA ▁gene , ▁in ▁particular , ▁has ▁three ▁important ▁features ▁that ▁make ▁it ▁highly ▁convenient ▁for ▁the ▁purpose . ▁▁ 1 -) ▁The ▁gene ▁is ▁located ▁on ▁X ▁chrom os ome ▁and ▁it ▁goes ▁through ▁in activ ation ▁by ▁m eth yl ation ▁in ▁normal ▁emb ry ogen esis ▁of ▁a ▁female ▁infant . ▁The ▁fact ▁that ▁most - but ▁not ▁all - gen es ▁on ▁X ▁chrom os ome ▁under go ▁in activ ation , ▁this ▁feature ▁becomes ▁an ▁important ▁one . ▁▁ 2 -) ▁Human ▁And ro gen ▁Re ceptor ▁gene ▁alle les ▁have ▁varying ▁numbers ▁of ▁C AG ▁repe ats . ▁Thus , ▁when ▁DNA ▁from ▁a ▁health y ▁female ▁t issue ▁is ▁ampl ified ▁by ▁PC R ▁for ▁a ▁specific ▁region ▁of ▁the ▁gene , ▁two ▁separated ▁bands ▁can ▁be ▁seen ▁on ▁the ▁gel . ▁▁ 3 -) ▁The