Furthermore, the CSA of the right vagus nerve was higher in comparison to the left vagus nerve in PD as well as in CIDP patients and controls (PD, 2.2 ± 0.6 mm2 versus 2.0 ± 0.6 mm2, P = 0.0064; CIDP, 2.9 ± 1.2 mm2 versus 2.3 ± 1.0 mm2, P = 0.0004; controls, 2.5 ± 0.6 mm2 versus 2.1 ± 0.5 mm2, P = 0.0157) (Table 1, Supplemental Fig. 1). This evidence concerns the gene PMP22 and chronic inflammatory demyelinating polyradiculoneuropathy.