TPBG and Parkinson disease: Nonetheless, it is still obscure whether Tpbg deficiency directly causes such transcriptomic alteration, because this result might also have been an indirect consequence of the pathological changes manifested in the SNc of aged Tpbg KO mice; that is, up-regulation of genes involved in PD may reflect the occurrence of mDA degeneration in aged Tpbg KO mice.