  We focus on Fuchsian equations with four accessory parameters and three
singular points. We see that the Fuchsian equations admit a "degeneration
scheme" in some sense, which is expected to give rise to a degeneration scheme
of discrete isomodromic deformation equations with four-dimensional phase
space. We compute an example of discrete isomonodromic deformation equations of
a certain Fuchsian equation.
