More color options.

I know that we already have alot of colors and markings,but there are 2 othere colors that I feel like nobody has ever herd of one is called the pearl gene.The other gene is called brindle it kind of looks like chocolate syrup.

These have both been planned for the future.

There is no brindle gene in horses. The only confirmed genetic form of brindle is a skin disease in grey horses that is passed on maternally. Brindle is typically either a somatic mutation or skewed grey or roan.

Isn't it common for Chimerism to be mistaken for brindle as well in some cases? Or am I thinking of somethin else?

I think it's more of people mistaking brindle phenotype for a horse having chimerism. Chimerism is more rare even than somatic mutations. Certain SOME horses that can appear to have some brindle type pattern COULD be chimeras, but most are not tested.