Here, we tested the therapeutic efficacy of CRISPR/Cas9-mediated downregulation of PMP22 via targeting TATA-box of PMP22 P1 promoter region in the C22 mouse, a model of CMT1A by overexpressing human PMP22 gene (20), allowing for direct translation of the target sequence to the clinic. The gene discussed is PMP22; the disease is Charcot-Marie-Tooth disease type 1A.