▁True ▁white ▁horses ▁have ▁un p ig ment ed ▁skin ▁and ▁hair ▁due ▁to ▁the ▁incomplete ▁migration ▁of ▁mel an ocy tes ▁from ▁the ▁neural ▁cr est ▁during ▁development . ▁▁ ▁No ▁health ▁defect s ▁are ▁associated ▁with ▁the ▁cre am ▁gene . ▁ ▁This ▁is ▁also ▁true ▁of ▁the ▁normal ▁variations ▁in ▁skin , ▁hair ▁and ▁eye ▁color ▁encoded ▁on ▁the ▁human ▁M AT P ▁gene . ▁True ▁white ▁coat ▁color ing ▁can ▁be ▁produced ▁by ▁at ▁least ▁half ▁a ▁dozen ▁known ▁gen es , ▁and ▁some ▁are ▁associated ▁with ▁health ▁defect s . ▁ ▁Some ▁gen es ▁which ▁encode ▁a ▁white ▁or ▁near - white ▁coat ▁when ▁heter o zy g ous , ▁popular ly ▁called ▁" domin ant ▁white ," ▁may ▁be ▁le th al ▁in ▁hom o zy g ote ▁emb ry os . ▁Another ▁specific ▁mut ation ▁on ▁the ▁end oth elin ▁re ceptor ▁type ▁B ▁( ED NR B ) ▁gene ▁is ▁associated ▁with ▁the ▁frame ▁over o ▁pattern ▁produces ▁L eth al ▁white ▁synd rome ▁if ▁hom o zy g ous , ▁but ▁carri ers ▁can ▁be ▁identified ▁with ▁a ▁DNA ▁test . ▁ ▁Pre val ence ▁ ▁The ▁cre am ▁gene ▁is ▁found ▁in ▁many ▁bre eds . ▁▁ ▁It ▁is ▁common ▁in ▁American ▁bre eds ▁including ▁the ▁American ▁Qu arter ▁Hor se , ▁Morgan , ▁American ▁S addle bre d , ▁Tennessee ▁Walk ing ▁Hor se , ▁and ▁Missouri ▁Fox ▁T rot ter . ▁It ▁is ▁also ▁seen ▁in ▁the ▁M ini ature ▁horse