Defective mitochondrial fusion, altered respiratory function, and distorted cristae structure in skin fibroblasts with heterozygous OPA1 mutations

► Heterozygous OPA1 mutations are associated with defective mitochondrial fusion. ► Mitochondrial morphology may be elongated despite defective mitochondrial fusion. ► Mutant OPA1 cells have altered mitochondrial dynamic response to nutritional stress. ► Mitochondrial activities are significantly altered in mutant OPA1 cells. ► Physical link between OPA1 and OXPHOS proteins is widespread.