Rarity of the Alzheimer disease-protective APP A673T variant in the United States. - Wang LS; Naj AC; Graham RR; Crane PK; Kunkle BW; Cruchaga C; Murcia JD; Cannon-Albright L; Baldwin CT; Zetterberg H; Blennow K; Kukull WA; et al. (JAMA neurology, 2015)