Coat Colour H-Locus (Harlequin)

Coat colour in dogs is controlled by a wide range of different genes working together. These genes are often referred to as ‘loci’. The Harlequin, or H-locus, which corresponds to the gene PSMB7, is a particular locus that can affect the coat colour and pattern of the Great Dane. In dogs that also express Merle (M-locus mutation), the dominant mutation to the H-locus further modifies the coat colour, resulting in an unpigmented white base with irregular black spots. Harlequin cannot be expressed if the dog does not produce dark pigment (governed by the E-locus).
The Harlequin mutation is believed to be homozygous lethal, meaning that only carriers will be born.