(H-Locus) Harlequin Pattern In Great Danes
Harlequin is a coat pattern recognized only in Great Danes. The harlequin pattern is a result of a complex interaction between variances in the merle and the harlequin loci (M and H loci). The harlequin variant acts as a modifier of merle. All harlequin dogs must have one or two copies of the mutation responsible for the merle coloration pattern. Harlequin patterns cannot be expressed in dogs that are not merle or only have red pigment.
The dominant merle gene produces a coat consisting of dark spots on a diluted background. If a merle dog also inherits a single copy of the harlequin gene, the dark spots increase in size and the background pigment is eliminated.
Harlequin is presumed to be homozygous embryonic lethal. This means that if a dog inherits two copies of the H locus allele (H/H), the dog typically dies as an embryo and does not survive once born. No animals have been observed with 2 copies of the mutated gene. Therefore, all harlequin patterned dogs have only copy of the mutated gene (H/n). This means that all dogs are either n/n for harlequin (no harlequin pattern) or H/n (harlequin pattern).
According to research conducted Dr. Leigh Anne Clark at Clemson University, over 59% of harlequin-bred black or non-merle dogs (including those with the mantle coloration) carry the harlequin mutation.
H Locus Testing:
Animal Genetics offers a test for the H-Locus to determine if your dog carries a copy of the gene mutation. Dogs can be DNA tested at ANY age.
Animal Genetics accepts buccal swab, blood, and dewclaw samples for testing. Sample collection kits are available and can be ordered at Canine Test Now.
Testing Is Relevant For The Following Breeds:
Animal Genetics offers DNA testing for PSMB7 mutation. The genetic test verifies the presence of the mutation and presents results as one of the following:
Harlequin Pattern Results:
|N/H||Black||Animal tests positive for 1 copy of the PSMB7 mutation. Harlequin mutation is present. In order to express the Harlequin pattern the dog must carry at least one copy of both Merle (M) and on copy of black (E) pigment. When breeding 2 N/H dogs there is a 25% chance of an embryonic lethal offspring.|
|N/N||Brown||Animal tests negative for PSMB7 mutation. No copies of Harlequin mutation are present.|
Clark LA, KL Tsai, AN Starr, KL Nowend and KE Murphy. 2011. A missense mutation in the 20S proteasome β2 subunit of Great Danes having harlequin coat patterning. Genomics 97(4):244-248.