  It is pointed out that there are infinite classes of cases based on gauge
groups of the form SU(p)xSU(q)xU(1) in which gauge anomalies cancel
non-trivially for small sets of fermion multiplets that include symmetric
tensor representations. These cancellations are non-trivial in the sense that
no group-theoretic explanation in terms of embedding in a larger simple group
is apparent. The cases presented here could be useful for model building and
lead to models with extra leptons and an extra U(1) gauge interaction under
which the Standard Model fermions have distinctive charges. In many cases the
SU(q)xU(1) groups act as family symmetries.
