Recent advances in genetics have revealed that patients with certain CMT types, such as those with GJB1 or MPZ mutations, can also exhibit abnormal temporal dispersion or conduction block (Ginsberg et al., 2004, Gutierrez et al., 2000, Marques et al., 2010, Michell et al., 2009, Miki et al., 2013, Murphy et al., 2011, Street et al., 2002, Tabaraud et al., 1999) The utility of these parameters for differentiating CIDP from non-CMT1A genotypes remains uncertain. The gene discussed is PMP22; the disease is Charcot-Marie-Tooth disease.