  Adding right-handed neutrino singlets and/or fermion triplets to the particle
content of the Standard Model allows for the implementation of the seesaw
mechanism to give mass to neutrinos and, simultaneously, for the construction
of anomaly-free gauge group extensions of the theory. We consider Abelian
extensions based on an extra U(1)_X gauge symmetry, where X is an arbitrary
linear combination of the baryon number B and the individual lepton numbers
L_{e,mu,tau}. By requiring cancellation of gauge anomalies, we perform a
detailed analysis in order to identify the charge assignments under the new
gauge symmetry that lead to neutrino phenomenology compatible with current
experiments. In particular, we study how the new symmetry can constrain the
flavor structure of the Majorana neutrino mass matrix, leading to two-zero
textures with a minimal extra fermion and scalar content. The possibility of
distinguishing different gauge symmetries and seesaw realizations at colliders
is also briefly discussed.
