Given the potential role of PMP22 regulatory sequences in the gene-dosage effect, we decided to analyze an extended region of the 5′UTR sequence encompassing 5000 kb and the coding sequence of the PMP22 gene in patients with CMT1A/HNPP (duplication/deletion of the PMP22 gene). This evidence concerns the gene PMP22 and Charcot-Marie-Tooth disease type 1A.