the supplementary category on "M(merle) Locus" part. Since the original section only talk about just one allele M, but there are some variation on the one allele and derive a number of new alleles, which will lead to the other production of pigment. Cryptic merle (Mc and Mc+) One of the variation of M allele is Mc and Mc+. Although just one copy of Mc is not long enough to make visible change on coats, the combination of Mc or more than two copies of Mc would lead to odd shade of black/liver. Atypical merle (Ma and Ma+) Another type of variation of M allele is Ma and Ma+. This kinds of allele would lead to visibly merle-patterned dog if there are two copies of Ma. It is important to be supplement because if the dog with atypical merle bred to dog with any longer merle allele, the double merle health problems might occur. S (spotting) locus The alleles at the S locus (the microphthalmia-associated transcription factor gene or MITF) determine the degree and distribution of white spotting on an animal's coat. There is disagreement as to the number of alleles that occur at the S locus, with researchers sometimes postulating a conservative two or, commonly, four alleles. The alleles postulated are: S = Solid color/no white (very small areas of white may still appear; a diamond or medallion on the chest, a few toe tips/toes, or a tail tip) si = Irish-spotting (white on muzzle, forehead, feet, legs, chest, neck and tail) sp = Piebald (varies from coloured with Irish spotting plus at least one white marking on the top or sides of the body or hips, to mostly white which generally retains patches of colour around the eyes, ears and tail base) sw = Extreme piebald spotting (extremely large areas of white, almost completely white) In 2014, a study found that a combination of simple repeat polymorphism in the MITF-M Promoter and a SINE insertion is a key regulator of white spotting and that white color had been selected for by humans to differentiate dogs from their wild counterparts. Based on this research the degree of White Spotting is dependent on the Promoter Length (Lp) to produce less or more color. A shorter Lp creates less white (Solid Colored and Residual White dogs) while a longer Lp creates more white (Irish Spotting and Piebald). What separates Piebald from