  We consider $SO(10)$ Grand Unified Theories (GUTs) with vacuum expectation
values (vevs) for fermion masses in the $\mathbf{10} + \mathbf{\overline{126}}$
representation. We show that the baryon asymmetry generated via leptogenesis is
completely determined in terms of measured low energy observables and of one
single high energy parameter related to the ratio of the $\mathbf{10}$ and
$\mathbf{\overline{126}}$ $SU(2)$ doublet vevs. We identify new decay channels
for the heavy Majorana neutrinos into $SU(2)$ singlet leptons $e^c$ which can
sizeably affect the size of the resulting baryon asymmetry. We describe how to
equip $SO(10)$ fits to low energy data with the additional constraint of
successful leptogenesis, and we apply this procedure to the fits carried out in
ref.~\cite{Dueck:2013gca}. We show that a baryon asymmetry in perfect agreement
with observations is obtained.
