  In this work we propose a renormalizable model based on the $SU(5)$ gauge
group where neutrino mass originates at the two-loop level without extending
the fermionic content of the Standard Model (SM). Unlike the conventional
$SU(5)$ models, in this proposed scenario, neutrino mass is intertwined with
the charged fermion masses. In addition to correctly reproducing the SM charged
fermion masses and mixings, neutrino mass is generated at the quantum level,
hence naturally explains the smallness of neutrino masses. In this set-up, we
provide examples of gauge coupling unification that simultaneously satisfy the
proton decay constraints. This model has the potential to be tested
experimentally by measuring the proton decay in the future experiments. Scalar
leptoquarks that are naturally contained within this framework can accommodate
the recent B-physics anomalies.
