Restoration of complex V deficiency caused by a novel deletion in the human TMEM70 gene normalizes mitochondrial morphology

► We report a complex V deficient patient due to a novel homozygous TMEM70 deletion. ► Mitochondria are swollen and irregularly shaped with loss of cristae. ► The mitochondrial network is fragmented.► Mitochondrial morphology is restored by complementation of the TMEM70 defect. ► TMEM70 is not restricted to higher multi-cellular eukaryotes.