Sequence comparison of the dopamine receptor D4 exon III repetitive region in several species of the order Carnivora.

It was previously demonstrated that the dog dopamine receptor D4 (DRD4) gene is polymorphic in terms of the repeat number and/or order of 39- and 12-bp sequences located in the third exon. To examine whether or not the repetitive region is present in other species of the order Carnivora, the homologous region of DRD4 genes were sequenced in the gray wolf, raccoon dog, Asiatic black bear, common raccoon and domestic cat. In the family Canidae, the wolf had an identical sequence to that of the dog 447b allele, and a repetitive sequence similar to the dog DRD4 was also recognized in the raccoon dog. On the other hand, no obvious repeated structure was observed in the sequences of the bear, raccoon and cat.