  We consider a supersymmetric SO(10) model with a SU(3) symmetry of flavour in
which fermion masses emerge via the see-saw mixing with superheavy fermions in
16+16bar representations. In this model the dangerous D=5 operators of proton
decay are naturally suppressed and flavour-changing supersymmetric effects are
under control. The mass matrices for all fermion types (up and down quarks,
charged leptons as well as neutrinos) appear in the form of combinations of
three rank-1 matrices, common to all types of fermions, with different
coefficients that are successive powers of small parameters, related to each
other by SO(10) symmetry properties. Two versions of the model are considered,
in which approximate grand unification of masses takes place between quarks and
leptons of the first family (with very small \tan\beta) or for the ones of the
second family (predicting moderate \tan\beta ~ 7-8). The second version
exhibits an interesting mechanism of unification of the determinants of the
Yukawa matrices of all types of fermions at the GUT scale and it provides a
perfect fit of the known data for fermion masses, mixing and CP-violation. It
predicts a hierarchical pattern of neutrino masses with non-zero theta_e3,
within 2-7 degrees. In addition, it predicts the correct sign of the baryon
asymmetry of the Universe via the leptogenesys scenario.
