  In this paper we study an SU(5) x A5 flavour model which exhibits a neutrino
mass sum rule and golden ratio mixing in the neutrino sector which is corrected
from the charged lepton Yukawa couplings. We give the full renormalizable
superpotential for the model which breaks SU(5) and A5 after integrating out
heavy messenger fields and minimising the scalar potential. The mass sum rule
allows for both mass orderings but we will show that inverted ordering is not
valid in this setup. For normal ordering we find the lightest neutrino to have
a mass of about 10-50 meV, and all leptonic mixing angles in agreement with
experiment.
