Harlequin is a pattern seen in Great Danes resulting from the complex interaction of the Merle and Harlequin genes on black pigment.
Phenotype: Harlequin Great Danes display a pattern of irregular dark patches on a white background. The show standard, officially recognized Harlequin pattern is black and/or gray patches on a white background, but patches may also be dilute blue ("blue harlequin" or "bluequin"), brindle ("brindlequin"), or sable ("fawnequin").
Mode of Inheritance: Autosomal dominant
Alleles: N = Normal (non-Harlequin), H = Harlequin
Breeds appropriate for testing: Great Dane
Explanation of Results:
Dogs with N/N genotype will not display Harlequin patterning; they lack this Harlequin variant. They cannot pass this Harlequin variant to any of their offspring.
Dogs with N/H genotype are expected to express the Harlequin coat pattern if they also possess the Merle gene and produce black pigment. They may transmit this Harlequin variant to 50% of their offspring. Breedings between two N/H genotype dogs are expected to result in 25% embryonic lethal offspring.
Dogs with H/H genotype are expected to terminate in utero (embryonic lethal genotype).
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The interaction of many genes is involved in the variety of colors and patterns of dog coat color. Harlequin is a pattern seen in Great Danes resulting from the complex interaction of the Merle (PMEL17) and Harlequin (PSMB7) genes on black pigment. The dominant Merle gene by itself produces dark spots on a dilute background on eumelanistic dogs. If a merle dog also inherits 1 copy of the Harlequin gene, the dark spots increase in size and the background pigment is removed altogether. Dogs that are not merle, or only have red pigment, cannot express the Harlequin gene. Two copies of Harlequin have not been observed and is presumed to be embryonic lethal, thus all Harlequin patterned dogs have only 1 copy of the mutation.
1 copy of the Harlequin mutation is present. If the dog has merle and is black pigmented, the Harlequin pattern is expressed. Breedings between N/H dogs are expected to result in 25% embryonic lethal offspring.
Clark, L.A., Tsai, K.L, Starr, A.N., Nowend, K.L, & Murphy, K.E. (2011). A missense mutation in the 20S proteasome β2 subunit of Great Danes having harlequin coat patterning. Genomics,97(4), 244-248. doi: 10.1016/j.ygeno.2011.01.003