Clinical Comments: Harlequin coat pattern in Great Danes is influenced by the PSMB7 gene, also known as H-Locus. Harlequin is a pattern resulting from interaction of the Merle (M-locus) gene and the Harlequin (H-locus) gene on black pigment. The Harlequin pattern is only expressed if a dog has at least one copy of the M allele in combination with at least one copy of the E or Em allele on the E-locus. If a Merle dog also inherits one copy of the Harlequin gene, the dark spots increase in size and the background pigment is removed (turns white). The result is the characteristic "torn" spots as opposed as the round spots on a Dalmatian. The coat pattern starts to become apparent within a few hours after birth, to full expression several weeks after birth. Please note, that the Harlequin mutation in Great Danes is in homozygous state (two copies of the mutation) considered embryonic lethal as no live dogs with two copies of the mutation have been observed. Many registration bodies and Breed Clubs ban or discourage any matings between Harlequin x Harlequin dogs for this reason.