We study the zeros in connection with perturbed recurrence coefficients of polynomials satisfying a certain three-term recurrence relation. As a particular case, we consider the Askey para-orthogonal polynomials on the unit circle, ${_2}F_1(-n, a+b i; 2 a; 1-z)$, $a,b \in \re$, generalizing a recent result about the monotonicity of their zeros with respect to the parameter b. Finally, as a direct consequence of our approach, we obtain new results on monotonicity of zeros of orthogonal polynomials on the real line.
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