Isospin breaking in supersymmetric left-right models

We construct a supersymmetric Pati-Salam model in which spontaneous breaking of parity invariance leads to new one-loop contributions to the D-quark masses only. It is argued that this mechanism may resolve the apparent inconsistency of the inequality $m_u$$m_d$ with the ones $m_c$>$m_s$ and $m_t$>$m_b$. We discuss possible embedding of the model in SO(10).