Mo' mA, mo' problems.

CAG-repeat expansions underlie fatal neurodegenerative disorders. In a lodestar study published in a recent issue of Nature, Sun et al. identify a writer and eraser of N-methyladenosine (mA) modifications of CAG-repeat RNA. They establish that mA modifications in CAG-repeat expanded RNA promote neurodegeneration and aberrant phase transitions of TDP-43. These findings suggest therapeutic strategies for CAG-repeat expansion disorders.