The 12 Bar Blues in Ab contains the chords Ab7 (I chord), Db7 (IV chord) and Eb7 (V) chord. Below is the 12 Bar Blues starting on Ab7.
12 Bar Blues in Ab (Jazz Variation)
The Jazz variation of the 12 Bar Blues in Ab adds some extra chords. The 12 Bar Blues structure remains the same, but certain chords are substituted. For example, the Ab7 chord in the fourth bar is substituted with a Ebm7 moving to an Ab7 chord.