However, pure AD is increasingly recognized as not being the most prevalent form of the disease.1, -, 3 Concomitant forms of pathologic proteins such as α-synuclein (α-syn) and TAR DNA-binding protein 43 (TDP-43) have been reported in over 40%4 and 50%5 of the AD cases, respectively. Here, SNCA is linked to Alzheimer disease.