A favourite disability assistance breed in many countries, Labradors are frequently trained to aid those with blindness or autism, act as a therapy dog, or perform screening and detection work for law enforcement and other official agencies. The breed is best known for their obedience, loyalty, and playful composure. Additionally, they are prized as sporting and hunting dogs. A dog with the recessive e allele will produce only phaeomelanin pigment and will be yellow regardless of its genotype at the B locus. The genes known about previously have had their number increased by the introduction of the K locus, where the dominant 'black' allele KB is now known to reside. Black or chocolate Labradors therefore must have the KB allele.