Chen C, et al. - Using postmortem human midbrain, substantia nigra neurons exposed to various types of mitochondrial defects (including mitochondrial DNA point mutations, single and multiple deletions) were contrasted with neurons from healthy aged and Parkinson disease cases (either gender) at a single neuronal level in order to understand the pathological significance of mitochondrial defects for neuronal survival. Data recommended that in people with pathogenic mitochondrial defects, neurons respond to mitochondrial defects to survive and such an adaptation may involve transcription factor A.