Binary Icosahedral Flavor Symmetry for Four Generations of Quarks and   Leptons
  To include the quark sector, the $A_{5}\equiv I$ (icosahedron) four generation lepton model is extended to a binary icosahedral symmetry $I'$ flavor model. We find the masses of fermions, including the heavy sectors, can be accommodated. At leading order the CKM matrix is the identity and the PMNS matrix, resulting from same set of vacua, corresponds to tribimaximal mixings. 
Chian-Shu Chen, Thomas W. Kephart, and Tzu-Chiang Yuan
hep-ph