Mitochondrial DNA deletion mutation levels are elevated in ALS brains.

This study was performed to explore the potential role of mitochondrial DNA mutations in the neurodegenerative process in amyotrophic lateral sclerosis (ALS). Using a semi-quantitative assay, a common mitochondrial DNA deletion mutation (mt DNA4977) was assayed in brain tissue obtained from six sporadic ALS patients and compared to four controls. In each brain, levels of this mutation were measured in a brain region affected by neurodegeneration, the motor cortex (Brodmann area 4), and compared to the temporal cortex (Brodmann area 17). In the ALS but not control brains, levels of mt DNA4977 were an average of more than 30-fold (range 15-250) higher in Brodmann area 4. These results support and extend those of previous studies implying that mitochondria may participate in the neurodegenerative process in ALS.