  We make an attempt to study the present status of the tetra-maximal neutrino
mixing (TMM) pattern. It predicts all the three leptonic mixing angles
$\theta_{13} \approx 8.4^\circ, \theta_{12} \approx 30.4^\circ, $ and
$\theta_{23} = 45^\circ $ together with the three CP-violating phases $ -
\delta = \rho = \sigma = 90^\circ $. However, the latest global analysis of
neutrino oscillation data prefer relatively higher best-fit value of $
\theta_{12} $ as well as non-maximal values of both $ \theta_{23}, \delta $. In
order to explain the realistic data, we study the breaking of TMM pattern. We
first examine the breaking of TMM due to renormalization group (RG) running
effects and then study the impact of explicit breaking terms. We also examine
the effect of RG-induced symmetry breaking on the effective Majorana neutrino
mass in neutrinoless double beta decay experiments.
