PPARGC1A and Parkinson disease: While there have not been many studies conducted in iPSC-derived midbrain neurons that have examined the status of mitochondrial biogenesis compared to patient-derived fibroblasts, it is worth noting that a similar reduction in mitochondrial biogenesis - as evidenced by a significant reduction in mitochondrial content and PGC-1α mediated mitochondrial biogenesis, has been observed in Parkin-deficient iPSC-derived midbrain DA neurons from PD patients compared to their respective isogenic controls [89].