Harlequin (Coat colour H-Locus Dog)
Harlequin dogs show black patches on a white base coat. It is a modified version of the Merle colouration. This means that all dogs showing the Harlequin pattern in the phenotype also have one copy of the Merle mutation. Dogs without the mutation for Merle (m/m), can be carriers for Harlequin.
The colour is caused by the H allele of the H locus. Homozygous animals (H/H) die before birth.
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- 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.
Genotype and Lab Report
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.
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.