Cassiopeia Delta VII (also known as Serafin's Planet) was a planet in the Alpha or Beta Quadrants, and the location of a Human colony established by individuals suffering from an unnamed genetic disease. Their ability to overcome their illness also served them in taming this harsh planet.
In late 2365 or early 2366, seismic shifts on Serafin's Planet exposed a new and unknown radiation source, which had the effect of curing the colonists' illness, but also created within them the need to feed on the life-force of other living beings. These seismic activities gradually intensified to the point where the planet was literally tearing itself apart, and the colonists had to call for evacuation. The USS Enterprise-D responded to this call on stardate 43201.8. (TNG comics: "Serafin's Survivors", "Shadows in the Garden")