  We investigate the viability of thermal leptogenesis in type-I seesaw models
with leptonic flavour symmetries that lead to tribimaximal neutrino mixing. We
consider an effective theory with an A4 x Z3 x Z4 symmetry, which is
spontaneously broken at a scale much higher than the electroweak scale. At the
high scale, leptonic Yukawa interactions lead to exact tribimaximal mixing and
the heavy Majorana neutrino mass spectrum is exactly degenerate. In this
framework, leptogenesis becomes viable once this degeneracy is lifted either by
renormalization group effects or by a soft breaking of the A4 symmetry. The
implications for low-energy neutrino physics are discussed.
