To provide further clarity, future studies are now required in post-mortem human brains to evaluate whether Lewy pathology is a major feature of VPS35-linked PD [7], and furthermore, whether SNCA-linked PD brains exhibit reduced retromer subunits in affected regions or neurons similar to observations in AD, tauopathy and ALS brains [19, 33, 44, 45]. This evidence concerns the gene VPS35 and Parkinson disease.