The coat color phenotype ‘sable’ occurs in the English Cocker Spaniel dog breed. It closely resembles other canine color patterns known as domino/grizzle/pied (e^A allele) and grizzle/domino (e^G allele) determined by variants in the melanocortin 1 receptor gene (MC1R; ‘extension’ or E locus), a key multi-allele regulator of coat color. We examined genetic variation in MC1R, and found one new non-synonymous variant, c.250G>A (p.(Asp84Asn)), consistently associated with the English Cocker Spaniel ‘sable’ phenotype. We propose calling this newly identified allele e^H and further show that the e^A, e^H and e^G (previously known as E^G) alleles associate with similar phenotypes in dogs impacting genotypes regulated by beta-defensin 103 gene (CBD103; K locus) and agouti signaling protein gene (ASIP; A locus) in the absence of the E^M and E alleles. This suggests that all three alleles are putative reduced-function variants of the MC1R gene. We propose the revised and updated E locus dominance hierarchy to be E^M > E > e^A/e^H/e^G > e^1–3.

中文翻译：

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犬毛色 E 基因座更新：鉴定出一种新的 MC1R 变体，导致英国可卡犬出现“黑貂”毛色，并对 E 基因座优势等级进行更新

毛色表型“紫貂色”出现在英国可卡犬品种中。它与其他犬科动物的颜色模式非常相似，称为多米诺骨牌/灰色/斑纹（e ^A等位基因）和灰色/多米诺骨牌（e ^G等位基因），由黑皮质素 1 受体基因（MC1R ；“延伸”或 E 位点）的变异决定，黑皮质素 1 受体基因是关键的基因毛色的多等位基因调节剂。我们检查了MC1R的遗传变异，发现了一种新的非同义变异 c.250G>A (p.(Asp84Asn))，与英国可卡犬“黑貂”表型一致相关。我们建议将这个新发现的等位基因称为^e H ^，并进一步表明e ^A、e ^H和e ^G（以前称为EG ）等位基因与影响受β-防御素 103基因（CBD103；K 基因座）调节的基因型的狗的相似表型相关。）和agouti信号蛋白^基因（ASIP；A基因座），但缺少EM和E等位基因。这表明所有三个等位基因都是MC1R基因的推定功能降低的变体。我们建议修订和更新的 E 位点优势等级为E ^M  > ​​ E  >  e ^A / e ^H / e ^G  >  e ^1-3。