  Flavour symmetries have been used to constrain both quark and lepton mixing
parameters. In particular, they can be used to completely fix the mixing
angles. For the lepton sector, assuming that neutrinos are Majorana particles,
we have derived the complete list of mixing patterns achievable in this way, as
well as the symmetry groups associated to each case. Partial computer scans
done in the past have hinted that such list is limited, and this does indeed
turn out to be the case. In addition, most mixing patterns are already 3-sigma
excluded by neutrino oscillation data.
