Harlequin (Coat colour H-Locus Dog)

• The dog shows black patches on a white base coat.
• The colour is caused by the H allele of the H locus.
• Homozygous animals (H/H) die before birth.
• The Harlequin colouration is a modified version of the Merle colouration.
• All dogs showing Harlequin in the phenotype also have a copy of the mutation that causes Merle (M/m).
• Dogs without the mutation for merle (m/m), may be carriers for harlequin, but not show the harlequin colour pattern in the phenotype.
• Officially, the Harlequin phenotype has only been clearly identified in Great Danes.

Locus Information: H-Locus

This test detects a change in a single base pair in exon 2 of the PSMB7 gene.

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Inheritance: autosomal dominant.

→ Animals with one or two copies of the gene (H/h, H/H) show the Harlequin phenotype. Homozygous animals (H/H), however, die before birth.

Genotypes:

h/h = two copies non-functional

No predisposition for Harlequin, the dog has no Harlequin spotting.

H/h = One copy intact and one copy non-functional

Harlequin colouration is pronounced, the dog has black patches on a white base coat. (If a copy of the merle factor is also present M/m).

H/H = Two copies functional

Homozygous dogs die before birth.

Clark, LA., Tsai, KL., Starr, AN., Nowend, KL., Murphy, KE.: A missense mutation in the 20S proteasome β2 subunit of Great Danes having harlequin coat patterning. Genomics 97:244-8, 2011. Pubmed reference: 21256207. Doi: 10.1016/j.ygeno.2011.01.003.

Further information is available at Online Mendelian Inheritance in Animals.