From an article found here
we found that "technically, there is no such thing as a black panther
—it’s a term used for any big black cat. What we call black panthers are in fact jaguars or leopards and yes, they have spots, too. Their hair shafts produce too much melanin thanks to a mutation in their agouti genes, which are responsible for distributing pigment in an animal’s fur. Look carefully and you can see a panther’s spots as the sunlight hits them in just the right way."
Also found in the same article "Even though their coloring is what gives them (cats) a bad reputation, these felines may be getting the last laugh after all. The mutation that causes a cat’s fur to be black is in the same genetic family as genes known to give humans resistance
to diseases like HIV. Some scientists think
the color of these cats may have less to do with camouflage and more to do with disease resistance. They’re hoping that as more cat genomes are mapped, we may get a step closer
to curing HIV."