Table 1.

Reasons why RNA species in human brain are vulnerable to oxidative insults.

RNA species	(i) Abundance in a cell (ii) Mostly single-stranded form and less protection by proteins (iii) Localization in the vicinity of mitochondria, the major source of ROS (iv) No known repair mechanisms for oxidized RNA
Human brain	(i) High oxygen consumption rate (ii) High content of easily peroxidizable polyunsaturated fatty acids (iii) High content of transition metals that catalyze ROS-generating reactions (iv) Low content of antioxidant enzyme catalase

ROS: reactive oxygen species.