SNCA and Parkinson disease: Studies which use human cell lines, such as iPSCs derived from PD patients, do not replicate the differential expression patterns found in brain tissue but iPSC-derived dopaminergic neurons share similar expression signatures to dopaminergic neurons isolated post-mortem, while iPSCs harbouring SNCA mutations cluster with genetic animal models of PD, suggesting the ability of these study types to replicate relevant gene expression patterns in PD.