MFN2 is an essential transmembrane GTPase which mediates mitochondrial fusion. Fusion of mitochondria occurs in many cell types and constitutes an important step in mitochondria morphology, which is balanced between fusion and fission. MFN2 acts independently of the cytoskeleton, plays a central role in mitochondrial metabolism and may be associated with obesity and/or apoptosis processes. Overexpression induces the formation of mitochondrial networks. It plays an important role in the regulation of vascular smooth muscle cell proliferation. Defects in MFN2 lead to Charcot-Marie-Tooth disease, the most common inherited disorder of the peripheral nervous system.