▁is ▁a ▁single ▁nucle ot ide ▁polym orphism ▁on ▁the ▁mit och ond rial ▁chrom os ome . ▁m t - SN P s ▁are ▁often ▁used ▁in ▁mat ernal ▁gene alog ical ▁DNA ▁testing . ▁ ▁SN P ▁markers ▁A ▁single ▁nucle ot ide ▁polym orphism ▁( SN P ) ▁is ▁a ▁change ▁to ▁a ▁single ▁nucle ot ide ▁in ▁a ▁DNA ▁sequence . ▁The ▁relative ▁mut ation ▁rate ▁for ▁an ▁SN P ▁is ▁extremely ▁low . ▁This ▁makes ▁them ▁ideal ▁for ▁mark ing ▁the ▁history ▁of ▁the ▁human ▁gen etic ▁tree . ▁SN P s ▁are ▁named ▁with ▁a ▁letter ▁code ▁and ▁a ▁number . ▁The ▁letter ▁indicates ▁the ▁lab ▁or ▁research ▁team ▁that ▁discovered ▁the ▁SN P . ▁The ▁number ▁indicates ▁the ▁order ▁in ▁which ▁it ▁was ▁discovered . ▁For ▁example ▁M 1 7 3 ▁is ▁the ▁ 1 7 3 rd ▁SN P , ▁documented ▁by ▁the ▁Human ▁Population ▁Gen et ics ▁Labor atory ▁at ▁Stan ford ▁University , ▁which ▁uses ▁the ▁letter ▁M . ▁ ▁See ▁also ▁ ▁Y - SN P ▁Single - n uc le ot ide ▁polym orphism ▁Short ▁tan dem ▁repeat ▁H ap lo group ▁H ap lot ype ▁Gene alog ical ▁DNA ▁test ▁ ▁Category : Single - n uc le ot ide ▁polym orph isms <0x0A> </s> ▁Cord ell ▁D . ▁Me eks ▁Sr . ▁( Se ptember ▁ 2 5 , ▁ 1 9 1 4 Dec ember ▁ 8 , ▁ 1 9 8 7 ) ▁was ▁the ▁first ▁black