GDAP1 and Charcot-Marie-Tooth disease type 2: CMT2 is a highly heterogeneous genetic disorder but 4 genes are the most frequently involved : the GJB1 (connexin-32), MPZ (P0 or myelin protein-zero), MFN2 (mitofusin 2) and GDAP1 (ganglioside-induced differenciation-associated protein 1).