Known examples include the human Parkinson's disease-related PACRG-PARK2 gene pair, the highly homologous mouse surfeit Surf1-Surf2 gene pair, and the non-homologous mouse Sars2-Mrps12 gene pair, in which the expression of two genes is delicately regulated by a transcription factor: in these cases N-myc, YY-1, and NF-Y, respectively [13-15]. Here, PACRG is linked to Parkinson disease.