Over the past decade the genetics behind the majority of cases of Charcot-Marie-Tooth (CMT) disease have been revealed with speed and accompanying astonishment. The findings have been so interesting, and provided so many paradigms, that they are studied by all students of molecular genetics down to undergraduate level. The dominant disorder CMT1 provided the first well documented example of a large scale DNA rearrangement, mediated by flanking long repeat sequences, resulting in a disease causing gene duplication of the myelin protein PMP-22. CMT1 was split into the subclasses a and b, after the identification of mutations in P0, providing an early and excellent example of the “positional candidate gene” approach to gene identification …