MFN2 and cardiomyopathy: Even in the presence of endogenous mammalian Mfn2 or Drosophila dMfn, the 400Q mutant that was bioinformatically predicted to be the more pathological of the two mutants induced mitochondrial dysmorphology and conferred a severe cardiomyopathy phenotype, demonstrating dominant inhibition of endogenous mammalian and invertebrate Mfns by Mfn2 400Q.