In this talk we discuss \textit{solar} neutrino mixing sum rules, arising from charged lepton corrections to Tri-bimaximal (TB), Bi-maximal (BM), Golden Ratios (GRs) and Hexagonal (HEX) neutrino mixing.
We also discuss \textit{atmospheric} neutrino mixing sum rules, arising from preserving one of the columns of the above types of mixing.
We consider the sum rule predictions for θ12 and the cosine of the Dirac CP phase δ,
in terms of the other mixing angles, using up-to-date global fits of the neutrino oscillation data.
We also consider Littlest Seesaw models, based on constrained sequential dominance CSD(n) with n=2.5, n=3 and n≈3.45 (the latter favoured by modular symmetry),
using a new analysis to accurately predict the observables θ12, θ23 and δ.
