“…The simplest GUT gauge symmetry group is SU(5) [59], in which matter fields of standard model are assigned to be5 and 10 dimensional representations. In a generical GUT scheme the down-type quark and charged lepton Yukawa matrices are the crucial factor to produce GUT relations that connect θ 13 with Cabibbo angle, see [60,61]. We remark that a series of models based on discrete flavor symmetry group together with a GUT gauge group have been proposed, for example the SU(5) ×A 4 [62][63][64], SU(5)×S 4 [26,[65][66][67][68][69] and SU(5)×T [70], SO(10)×A 4 [71][72][73], SO(10)×S 4 [74][75][76][77][78][79][80], SO(10)×P SL 2 (7) [81,82] and SO(10)×∆ 27 [83].…”