A SUSY SU(5) Grand Unified Model of Tri-Bimaximal Mixing from A4
  We discuss a grand unified model based on SUSY SU(5) in extra dimensions and on the flavour group A4xU(1) which, besides reproducing tri-bimaximal mixing for neutrinos with the accuracy required by the data, also leads to a natural description of the observed pattern of quark masses and mixings. 
Guido Altarelli, Ferruccio Feruglio and Claudia Hagedorn