Associated Askey-Wilson polynomials as Laguerre-Hahn orthogonal polynomials

One looks for [formal] orthogonal polynomials satisfying interesting differential or difference relations and equations (Laguerre-Hahn theory). The divided difference operator used here is essentially the Askey-Wilson operator $$Df\left( x \right) = \frac{{E_2 f\left( x \right) - E_1 f\left( x \right)}}{{E_2 x - E_1 x}} = \frac{{f\left( {y_2 \left( x \right)} \right) - f\left( {y_1 \left( x \right)} \right)}}{{y_2 \left( x \right) - y_1 \left( x \right)}}$$ where y1(x) and y2(x) are the two roots of Ay2+2Bxy+Cx2++2Dy+2Ex+f=0.