Recently, mutations of F-box only protein 7 (FBXO7), an adaptor protein in Skp-Cullin-F-box ubiquitin E3 ligase complex (SCF complex), were found to induce early-onset juvenile autosomal recessive PD with rapidly progressive and serious PD symptoms (Parkinson disease-15, PARK15) [99]. Here, KITLG is linked to Parkinson disease.