MFN2 and nervous system disorder: In a recently published study in Science, Naòn et al. report two uncharacterized splice variants of Mitofusin 2 (MFN2) that specifically shape and tether the endoplasmic reticulum (ER) to mitochondria.1 This work sheds new light on the pleiotropic effects previously ascribed to MFN2 loss-of-function mutations, and has important implications for associated metabolic and neurological diseases.