  The transition distribution of a sample taken from a Wright-Fisher diffusion
with general small mutation rates is found using a coalescent approach. The
approximation is equivalent to having at most one mutation in the coalescent
tree of the sample up to the most recent common ancestor with additional
mutations occurring on the lineage from the most recent common ancestor to the
time origin if complete coalescence occurs before the origin. The sampling
distribution leads to an approximation for the transition density in the
diffusion with small mutation rates. This new solution has interest because the
transition density in a Wright-Fisher diffusion with general mutation rates is
not known.
