  We study polynomial identities satisfied by the mutation product $xpy - yqx$
on the underlying vector space of an associative algebra $A$, where $p, q$ are
fixed elements of $A$. We simplify known results for identities in degree $4$,
proving that only two identities are necessary and sufficient to generate them
all; in degree 5, we show that adding one new identity suffices; in degree 6,
we demonstrate the existence of a number of new identities.
