The Wldsmutation and transgene. The spontaneous mutation discovered in the Wldsmouse and the transgene used to make the various transgenic Wldsanimals including Tg4836 mouse, Tg23 and Tg79 rat lines. The triplication results in the Wldsmouse having one full copy of Nmnat1 (shown in orange) and Ube4b (shown in brown) at either ends if the triplicated region. Within the triplicated region are 2 copies of an in frame fusion of the N70 amino acids of Ube4b linked to the whole coding region of Nmnat1 leading to the expression of 18 amino acids which are normally contained within the 5' untranslated region of Nmnat1 (termed Wld-18 shown in red) which has been used for antibody targeting. Primers against the Wldssequence were designed to amplify bases 810–885 in the Genbank sequence AF260927 that correspond to a portion of the Nmnat-1 sequence in the chimeric Wldsproduct. Arrows indicate approximate site of amplification on the gene schematic. Figure modified from Gillingwater et al., 2006 .