Due to SUSY threshold corrections GUT scale Yukawa coupling ratios depend strongly on the SUSY spectrum. We phenomenologically constrain the parameter space of three common SUSY breaking schemes and find in this way possible GUT scale Yukawa coupling ratios. These are compared to group theoretical considerations where only due to the underlying GUT structure Yukawa coupling ratios are predicted. We find new viable relations useful for flavour model building. On that basis we propose a supersymmetric $A_4\times SU(5)$ model incorporating quasi-degenerate neutrinos via a type II seesaw contribution. Tri-bimaximal neutrino mixing arises from a type I seesaw contribution via $A_4$ family symmetry and constrained sequential dominance."
