Aside from the fact that such frameworks typically subsume DLB into a wider identity centred around PD, the ability of SAA to identify distinct disease states is predicated upon seed-competent α-synuclein pathology being relatively specific for primary Lewy body diseases; however, Lewy body pathology is a common feature of other conditions, particularly Alzheimer’s disease, where it occurs in over 50% of cases [14]. This evidence concerns the gene SNCA and Parkinson disease.