PRKN and Parkinson disease: Furthermore, the reduced expression of GHS-R1α was verified in induced pluripotent stem cells with a mutated or disrupted PARK2 gene, which is a mitochondrial gene implicated in mitochondrial quality control, mitophagy, and the development of early-onset PD (Pickrell and Youle, 2015), and in the SNpc of an in vivo model of PD (Suda et al., 2018).