Tg(SNCA)83Vle alphaS<+> A53T alpha-synuclein PRP Transgene transgene insertion 83, Virginia M-Y Lee alphaS<+>|Tg(SNCA)83Vle|M83|A53T alpha-synuclein PRP http://identifiers.org/mgd/MGI:3057168 Tg(Prnp-SNCA*A53T)83Vle M83 MGI:3057168 transgene O