Furthermore, the same perturbation of expression, being the downregulation of HDAC4-regulated genes TSPAN7, ATP1A3, RTN1, and PRKCB and the upregulation of ER stress genes ERO1A, PDIA6, and FKBP9, was seen in the same two idiopathic PD cases exhibiting HDAC4 mislocalization. The gene discussed is ERO1A; the disease is Parkinson disease.