, ▁various ▁mut ations ▁of ▁the ▁MC 1 R ▁gene ▁result ▁in ▁red ▁hair , ▁bl ond ▁hair , ▁fair ▁skin , ▁and ▁sus cept ibility ▁to ▁su nd am aged ▁skin ▁and ▁mel an oma . ▁A e um el an ic ▁hair ▁co ats , ▁associated ▁with ▁mut ations ▁of ▁the ▁MC 1 R ▁gene , ▁have ▁also ▁been ▁identified ▁in ▁m ice , ▁cattle , ▁dogs , ▁and ▁horses . ▁These ▁coat ▁colors ▁are ▁called ▁" yellow " ▁in ▁m ice ▁and ▁dogs , ▁" red " ▁in ▁cattle ▁and ▁ch est nut ▁in ▁horses . ▁The ▁loss ▁of ▁e um el an in ▁in ▁the ▁coat ▁is , ▁in ▁these ▁species , ▁har ml ess . ▁The ▁distinction ▁between ▁a e um el an ism ▁and ▁hyper pha e om el an ism ▁– ▁over ▁abund ance ▁of ▁ph ae om el an in ▁– ▁is ▁semantic . ▁ ▁A pha e om el an ism ▁A pha e om el an ism ▁is ▁the ▁ab normal ▁absence ▁of ▁ph ae om el an in ▁from ▁the ▁inte g ument ary ▁system ▁and / or ▁eyes . ▁Ph ae om el an in ▁is ▁produced ▁by ▁mel an ocy tes ▁in ▁the ▁absence ▁of ▁mel an oc ort in ▁ 1 ▁re ceptor . ▁This ▁absence ▁is ▁medi ated ▁by ▁ag out i ▁sign alling ▁protein , ▁which ▁ant agon izes ▁mel an oc ort in ▁ 1 ▁re ceptor . ▁L oss ▁of ▁function ▁of ▁ag out i