Profound downregulation of the RNA editing enzyme ADAR2 in ALS spinal motor neurons

► Inefficient GluA2 RNA editing is a cause of death of motor neurons. ► The RNA editing enzyme ADAR2 specifically catalyzes the GluA2 RNA editing. ► Motor neurons expressed unedited GluA2 in all the ALS cases examined. ► ADAR2 expression was reduced universally in ALS motor neurons. ► ADAR2 downregulation began preclinically in sporadic ALS.