  In this note, we use entanglement entropy as a tool to explore the universal
properties of CFTs dual to extremal BTZ black holes. We demonstrate that the
entanglement entropies computed in the CFTs at the boundary of the extremal BTZ
and the boundary of the near-horizon limit of the extremal BTZ are in perfect
agreement and have the form appropriate to a two-dimensional CFT with only the
chiral part excited and the anti-chiral in the ground state. Furthermore, we
analyze the universal limits of the entanglement entropy and recover the
correct value of the thermal entropy for large entangling intervals and the
first-law like relation for the small interval.
