GPX4 and Parkinson disease: Furthermore, reducing vesicular monoamine transporter 2 (VMAT2), exclusively found in neurons and an indicator of PD progression that has been clinically useful for early PD diagnosis (20), suggested that neurons were damaged and DA metabolism was disordered in A53T/Gpx4 CKD mice (Supplemental Figure 5D), accompanied by disordered DA metabolism (Supplemental Figure 5E).