This locus works similarly to the D-locus and CO-locus. The B-locus needs two copies of the testable chocolate gene in each of its alleles for the testable color to be expressed. A French bulldog that is blue (d/d) and testable chocolate (b/b) is called Isabella the French Bulldog. A dog that is blue (d/d), cocoa (co/co), or testable chocolate (b/b) is also called an Isabella French Bulldog. A dog that is blue (d/d), cocoa (b/b), and only carries one or no copies of testable chocolate is called a Lilac French Bulldog.
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