  We prove that a $q$-deformation $\Disc k\X q$ of the powers of the
discriminant is equal, up to a normalization, to a specialization of a
Macdonald polynomial indexed by a staircase partition. We investigate the
expansion of $\Disc k\X q$ on different basis of symmetric functions. In
particular, we show that its expansion on the monomial basis can be explicitly
described in terms of standard tableaux and we generalize a result of
King-Toumazet-Wybourne about the expansion of the $q$-discriminant on the Schur
basis.
