MFF and optic atrophy: Its targeting to the ER portion of MERCs greatly increases mitochondrial fission (Ji et al., 2017) Neuronal defects result, for instance, upon mutation of the MFF gene in the Leigh-like basal ganglia disease-optic atrophy-peripheral neuropathy syndrome, also referred to as encephalopathy due to defective mitochondrial and peroxisomal fission 2 (EMPF2, MIM#617086), due to defective mitochondrial and peroxisomal fission (Shamseldin et al., 2012).