Merle Genes
What is merle?
Merle is a highly dominant marking gene which dilutes random sections of the coat to a lighter shade, thus leaving patches of the original coat colour in tact. Unlike piebalding, the patches can appear anywhere on the body.
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Patches can appear as smooth spots, or may have 'jagged' or 'torn' edges.
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The gene only affects eumelanin (so Black ('KK', 'Kk' or 'kk'), Blue Dilution ('BBdd'), Liver ('bb') or Isabella Dilution ('bbdd').
It will not affect phaeomelanin (Red ('ee'), Lilac Dilution ('bedd'), Seal ('KS'), or Champagne Dilution ('eedd').
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Merle affects the coat, eye colour, and nose and may affect all, or only part of, the body depending on what other genes are in play.
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Some genes Merle may 'mask':
Sable
Shading
Brindling
Saddle
Merle is indicated by the gene 'Mm' or 'MM'. The gene is dominant, and so you are likely to get multiple merles in one litter.
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If your 'Mm' character partners with another 'Mm' canine, a standard litter of 4 will typically contain;
1 'Double Merle' ('MM')
1 'Non-Merle' ('mm')
and 2 'Regular Merles' ('Mm')
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The Range of Merle
On the canines displayed above, we have;
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Heavy Merle - Almost all the black colouring is turned blue.
Standard Merle - 50-90% of the body is blue.
Blanket Merle 30-40% of the body is blue.
Cryptic Merle - 1-20% of the body is blue.
This range is universal across all phenotypically Merle patterned canines.
bLUE MERLE
Blue Merle can be any shade of blue from near white to near black, all with black patching. Other genes may be present in the coat at the same time such as tan points, white spotting, masking, grizzle, domino...even ticking!
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To be classed as a 'true blue merle', your character must also be 'DD' - non-dilute- on the D Locus (so 'DD-Mm' or 'DD-MM').
rED mERLE
Red Merle can be any shade of red from near white to near liver, all with liver patching. Other genes may be present in the coat at the same time such as tan points, white spotting, masking, grizzle, domino...even ticking!
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To be classed as a 'true red merle', your character must also be 'bb' on the B Locus (Solid Liver), and 'DD' on the D Locus (Non-Dilute), thus making part of their genotype; 'bb-DD-Mm' or 'bb-DD-MM'.
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Dilute Blue Merle
Dilute Merle is what happens when a canine carrying the 'dd' gene also carries the 'Mm' gene.
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Where a 'Blue' Merle has black patches, a 'Dilute' has blue.
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The genotype denoting this manifestation is 'dd-Mm'.
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Dilute Red Merle
A diluted version of Red Merle.
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The genotype is denoted by 'bb-dd-Mm'.
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Muddy Merle
Also known as 'Ticked Merle' but does not require the the Ticking gene to appear.
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Muddy merle may be presented in any colour merle and is represented by 'Mmt'
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Double Merle
Also known as 'lethal merle'. Double merle is associated with a whole host of health problems including deafness, blindness, skin conditions, neurological disorders and sensitivity to sunlight. Double merle may manifest in any colour associated with the merle gene.
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The gene is represented by 'MM' in a genotype.
Double merle creates an extensive range of white masking all over the body unrelated to harlequin modifiers, piebalding or tweed.
Phantom Cryptic Merle
Denoted in a genotype by 'CRMm'.
Phantom Cryptic merle is a canine who looks completely normal in colour with little to absolutely no indication of merle. The only way to tell is via their nose and eyes (eyes will either be or partly be a bright vibrant blue, and nose will be either pink with black spotting or vice versa).
pseudo harlequin
Because the dilution caused by Merle has such an extensive range, the lightest colours often tend to look 'white' and give the appearance of 'Harlequin' (below).
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This is why these canines are referred to as being 'Pseudo Harlequin'.
Merle mODIFIER Genes
wHAT aRE mERLE mODIFIERS AND WHAT DO THEY DO?
A merle modifier is a gene that, when paired with merle affects how the merle gene itself is translated onto a canine. A canine which has a modifier gene but not the merle will not be affected.
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tWEED (pATCHWORK)
Standard Tweed causes the diluted part of a canine caused by merle to turn into various shades of brown, tan and grey. It is represented by 'Tw' in a genotype.
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Patchwork Tweed is somewhat rarer than its standard counterpart and can cause white patches in the coat unrelated to piebalding or harlequin. This variant is represented by 'TwP'.
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tWEED (Irregular)
Irregular Tweed is slightly different to the two other variants as it only presents minimal patching with large amounts of the original coat colour remaining intact but heavily 'ticked', though this is nothing to do with the Ticking gene.
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This gene is represented by 'TwT'.
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Harlequin
Turns the dilution between the dark patching on a blue or red merle totally white. A canine can be a Harlequin without merle being present, in which case; random white areas will be created within the coat.
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Harlequin is represented by 'Hh'.
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A canine can never be 'Double Harlequin' ('HH') as this is a lethal gene and will cause the affected puppy to be absorbed in the womb.
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Dilute Harlequin
As above but applicable only to canines carrying the 'dd' gene.
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Fawnequin
Harlequin markings which break up a 'standard sable' coat.
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To be classed a 'Fawnequin', the canine MUST carry the 'Ay', 'Em' and 'Hh' gene without Merle ('Mm' or 'MM').
oTHER MANIFESTATIONS
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Brindlequin
(Kbr-Ay-Hh)
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Few Spot Harlequin
(HhT)
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Irish Harlequin
(Hh-sisi)
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