Let $u$ be a form and the corresponding Hankel determinants $\Delta_n(u)$ ; suppose that there exists $r\in\mathbb{N}$ such that $\Delta_n(u)\neq 0$ for $0\leq n\leq r$ and
$\Delta_{r+1}(u)= 0$. We are posing the question: for what supplementary conditions is it possible to construct a monic polynomial sequence $\{P_{n}\}_{n\geqslant 0}$ orthogonal with respect to $u$ such that $\deg P_n=n,\ n\geqslant 0$ ? Otherwise stated $\cal P$ must be generated by $\{P_{n}\}_{n\geq 0}$, which leaves out finite sequence.