Issues to overcome include developing tracers for intracellular targeting with ideal lipophilicity and tracer selectivity for α-syn over amyloid and tau aggregates.369,370 More recently, however, a newly developed α-syn PET tracer, 18F-ACI-12589, was shown to bind to basal ganglia and cerebellar white matter in a small cohort, although this was confined to MSA patients.371 Larger studies examining diagnostic accuracy for distinguishing PD from MSA will be critical. This evidence concerns the gene MAPT and Parkinson disease.