It is also possible that anti-ARHGAP26 autoantibodies, as a rare autoimmune disease, may be the cause of the subject's clinical and laboratory features with altered dopamine transporter uptake, dementia, and mild Parkinsonian symptoms rather than idiopathic DLB (fulfilling only two core features and with inconsistent cognitive and imaging findings). This evidence concerns the gene ARHGAP26 and autoimmune disease.