On quasidegeneracy of Majorana neutrinos and the observed pattern of   Leptonic mixing
  We relate the observed pattern of leptonic mixing to the quaidegeneracy of three Majorana neutrinos. We show how lifting the degeneracy may lead to the measured value of $|U_{13}|$ and to sizeable CP violation of Dirac-type. We show some of the correlations obtained among physical observables, starting from some of the most interesting schemes proposed in the literature. 
M. N. Rebelo
hep-ph