SNCA and early-onset autosomal dominant Alzheimer disease: For example, aggregated alpha‐synuclein, a hallmark of Parkinson's disease, can also be found in Alzheimer's disease (Hamilton, 2000; Mandal et al, 2006), and aggregated TDP‐43, a hallmark of Amyotrophic Lateral Sclerosis (ALS), can also be found in both Alzheimer's disease and Parkinson's disease (Higashi et al, 2007; Nakashima‐Yasuda et al, 2007).