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Ohio%4'H%Horse%Program%www.horse.osu.edu*
Coat Color Genetics
Elizabeth Share, Lorain County 4-H Educator Masa Williams, State Extension Associate
Excellence%in%Junior%Fair%Ac9vi9es%
Ohio%4'H%Horse%Program%www.horse.osu.edu*
• *What*is*Gene1cs?*
• *Major*Color*Loci*
• *E,*A,*C,*D*
• *Major*Modifying*Loci*
• *G,*Rn,*T*
• *Changes*to*Coat*Color*Gene1cs*in*Upcoming*Resources*
• *Horse*Smarts*vs*The*Horse*
• *Color*Gene1cs*Games*
• *Catch*a*Horse*• *Matching*and*Memory*
What We Will Cover Today
• *The*study*of*heredity*and*the*varia1on*of*inherited*characteris1cs.*
What is Genetics?
• %Inside%every%living%cell%are%sets%of%instruc9ons%called%GENES%
• GENES%provide%instruc9on%on%what%the%animal%looks%like,%how%it%is%to%survive,%etc.%• Each%cell%contains%25,000'35,000%GENES%
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• GENES%are%strung%together%in%long%strands%of%DNA%called%CHROMOSOMES%• Horses%have%pairs%of%chromosomes%(one%from%each%parent)%located%in%the%nucleus%of%their%cells%
What is Genetics?
https://history.nih.gov/exhibits/genetics/kids.htm
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• One%chromosome%can%contain%hundreds%to%thousands%of%pairs%of%GENES%• Genes%are%located%at%a%physical%posi9on%on%the%chromosome%called%a%LOCUS%%
Genetics
https://history.nih.gov/exhibits/genetics/kids.htm
E E
• Like%chromosomes,%genes%also%come%in%pairs%• These%genes%pairs%are%known%as%ALLELES%
Locus
Alleles
• Alleles%found%on%a%locus%can%be%either%%• %The%same,%known%as%HOMOZYGOUS%• %Different,%known%as%HETEROZYGOUS%
Genetics
https://history.nih.gov/exhibits/genetics/kids.htm
E E Homozygous
E e Heterozygous
• Addi9onally,%genes%found%on%a%locus%can%be%either%%• %DOMINANT,%usually%denoted%by%“capital%leZers”%• %RECESSIVE,%usually%denoted%by%“lower'case”%leZers%
Genetics
https://history.nih.gov/exhibits/genetics/kids.htm
• In%most%cases%of%heterozygous%alleles,%dominant%genes%mask%the%expression%of%recessive%ones!%
E e E E Dominant Recessive
• *The%GENOTYPE%represents%the%actual%gene9c%makeup%of%an%animal,%for%example:%
% % % % % % %%% % % % % %%%=%
Genetics
• *The%PHENOTYPE%represents%what%the%animal%looks%like%based%on%the%gene9c%interac9on%of%the%alleles%present%
eeAAddCC%
Loci
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• E'%Extension%Gene%
• A'%Agou9%Gene%
• C'%Cream%Gene%
• D'%Dun%Gene%
Major Color Loci
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• *‘E’*or*‘e’*• Determines*BLACK*‘E’**or*RED*‘e’*
• BLACK*is*dominant*
• *Genotypically*expressed*as*EE*or%Ee%• RED*(chestnut,*sorrel)*is*recessive*
• *Genotypically*expressed*as*ee%• *Considered*BASE*COAT*colors*
• ALL*other*colors*are*modifica1ons/restric1ons*of*these*two*base*coats*
Extension Locus
ee EE or Ee
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• *‘A’*or*‘a’*• *‘A’*S*restricts*black*pigment*to*points**
• *Points=*(mane,*tail,*lower*legs,*ear*rim,*muzzle)*
• *‘a’*S*does*not*restrict*black*pigment*to*points*
• Produces%Bays%and*Browns%on*a*Black*coat*(EE*or*Ee)*• Does*NOT*affect*red*(ee)*
• Agou1*is*dominant*
• *Genotypically*expressed*as*AA*or%Aa%• *Recessive*genotypically*expressed*as*aa%
Agouti Locus
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• *‘C’*or*‘ccr’**• In*this*case,*‘ccr*’*is*the*dominant*allele*
• Known*as*the*DILUTION*gene*• *‘ccr’Smodifies*the*base*coat*color*by*reducing*level*of*
pigmenta1on*
• Can*have*PARTIAL%DOMINANCE%gene*ac1on*• Heterozygote*is*intermediate*between*two*homozygotes*
• *Expressed*when*Cccr*• Known*as*SINGLE%DILUTION%• Red*(ee)*will*be*Palomino*(ee*Cccr)*
• *Bay*(EEAA,*EEAa,*EeAA,*EeAa)*will*be*Buckskin*(E_A_Cccr)*• Black*(Eeaa,EEaa)*will*be*Smoky*Black*BUT*will*
phenotypically*appear*Black*
Cream Locus
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• Homozygote*is:*
• *Expressed*when*ccrccr*• Known*as*DOUBLE%DILUTION%• *‘ccrccr’Smodifies*the*base*coat*color*by*reducing*level*of*
pigmenta1on*even*more*
• Red*(ee)*will*be*Cremello*(ee*ccrccr)*
• *Bay*(EEAA,*EEAa,*EeAA,*EeAa)*will*be*Perlino*(E_A_ccrccr)*• Black*(Eeaa,EEaa)*will*be*Smoky*Cream*(E_aaccrccr)*
• Phenotypically,*all*double*dilu1ons*can*appear*the*same*
• Creamy*in*color*
• Blue*or*green*eyes*• Predominantly*pink*skin*
• White*markings*may/may*not*be*visible*
Cream Locus
Cream Locus- Double Dilution
ee AA or Aa or aa E_A_
E_aaccrccr
E_aa
E_A_ccrccr ee AA or Aa or aaccrccr
Dun Locus • *‘D’*or*‘d’*
• ‘D*’*dilutes*base*coat*color*
• *‘d’*–*does*not*dilute*coat*color*
• Produces%Grullo%on*a*Black*coat*(E_aa)*• Produces%Dun%on*a*Bay*coat*(E_A_)*• Produces%Red%Dun%on*a*Red*coat*(ee)*
• Dun*is*dominant*
• *Genotypically*expressed*as*DD*or%Dd%• *Recessive*genotypically*expressed*as*dd*
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• *‘G’*or*‘g’*• *‘G’*–progressively*grays*out*base*coat*
• *Masks*gene*expression*of*all*other*color*genes*
• *‘g’*–*allows*regular*color*expression*
• Produces%Gray%on*all*coat*colors!*• Black,*Bay,*Red,*Roan,*Appaloosa,*Paint*
• Gray*is*dominant*
• *Genotypically*expressed*as*GG*or%Gg%• *Recessive*genotypically*expressed*as*gg%
Gray Locus
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• *‘Rn’*or*‘rn’*• *‘Rn’*–results*in*white*hairs*mingled*with*basic*coat*color*hairs*
• White*hairs*do*not*increase*in*frequency*with*age*aaer*adult*
coat*
• *‘rn’*–*does*not*affect*base*coat*color*
• Produces%Blue%Roan%on*a*Black*coat*(E_aa)*• Produces%Bay%Roan%on*a*Bay*coat*(E_A_)*• Produces%Red%Roan%on*a*Red*coat*(ee)*• Phenotypically*can*affect*ALL%coat%colors%
• ie.*palomino*roan,*dun*roan,*buckskin*roan,*grullo*roan**
• Roan*is*dominant*
• *Genotypically*expressed*as*RnRn*or%Rnrn%• *Recessive*genotypically*expressed*as*rnrn*
Roan Locus
• *‘T’*or*‘t’*• *‘T’*–paben*for*white*spocng*
• White*over*back*and*high*leg*white*
• *‘t’*–*does*not*cause*spocng*
• Can*affect*all*coat*colors*
• Tobiano*is*dominant*
• *Genotypically*expressed*as*TT*or%Ta%• *Recessive*genotypically*expressed*as*Z%
Tobiano Locus
• *Remember'%a%horse’s%GENOTYPE%(gene9c%code)%determines%his%PHENOTYPE%(what%he%looks%like)%
% % % % % % %%% % % % %%%%%%%%%%%%%%%%%%=%
Genetics
• Most%horses%do%not%possess%ALL%color%genes%discussed%today!%
Ee Aa Cccr dd
Extension Agouti
Dun Cream
HORSE COAT COLOR PANEL TEST RESULTSMAYA WISDOM
01-Feb-2017
8128 PLANKTOWN RD.SHILOH, OH 44878
Case: NQ34468
Print Date:
Date Received: 26-Jan-2017
Horse: 16F TAXI'S DIAMOND
Sire:Dam:
2010043197Reg:
Report ID: 4552-3112-9555-1044Verify report at www.vgl.ucdavis.edu/myvgl/verify.html
TAXI'S DIAMONDALLIANCE'S GONE N DUN IT
2006014721
Reg:
Reg:
DOB: 05/25/2016 Sex: Mare Breed: Rocky Mountain Horse
RED FACTOR E/e Both black and red factors detected. SPLASHEDWHITE
Not requested.
AGOUTI a/a If present, black pigment is distributeduniformly over the body. LEOPARD Not requested.
CREAM N/Cr 1 copy of Cream dilution detected. PATTERN-1 Not requested.
PEARL N/N No copies of Pearl dilution detected. GRAY Absent Gray gene is absent. Horse will not turn gray.
SILVER Z/Z 2 copies of Silver dilution detected. Horse isexpected to have MCOA eye abnormalities. DUN D/nd2 1 copy of Dun dilution and 1 copy of nd2.
LETHAL WHITEOVERO
Not requested.DOMINANT
WHITE (W5, W10,W20)
Not requested.
SABINO 1 Not requested.
TOBIANO Not requested.
CHAMPAGNE N/N No copies of Champagne dilution detected.
For more detailed information on Horse Coat Color results, please visit:www.vgl.ucdavis.edu/services/coatcolorhorse.php
Tests for Gray, Leopard/Appaloosa, Lethal White Overo and Tobiano are performed under license.
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• Dun:*• The*Horse:*DD*or*dd*• Horse*Smarts:*DD*or*d1,*d2*
• Cream:*
• The*Horse:*CC=no*dilu1on*(recessive),*****ccrS*dilu1on*(dominant)*
• Horse*Smarts:*CR=dilu1on*(dominant)*
**cr=*no*dilu1on*(recessive)*
• Roan:*• The*Horse:*RnRnS*listed*as*lethal*• Horse*Smarts:*RNRN*
• RNRNS*no*longer*thought*to*be*lethal*• No*“strawberry*roan”**
Upcoming Changes
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• Tobiano:*• The*Horse:*TT*or*b*• Horse*Smarts:*TO*or*to*
• Overo:*• The*Horse:*OO=*no*spocng*pabern**(dominant)S*allows* *
* * *** ******normal*expression*of*genes*at*other*loci,**
* * ****Oo=*no*spocng*pabern**(dominant)*
***oo=*spocng*pabern**(recessive)*
*****oe=*causes*lethal*when*homozygous*(recessive*
******for*overo*spocng*pabern*)*
• Horse*Smarts:*OO=*lethal*
* * ****Oo=*spocng*pabern*(dominant)*
***oo=**no*spocng*pabern*(Recessive)*
Upcoming Changes
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• Appaloosa:*• The*Horse:*Ap*or*ap*• Horse*Smarts:*Lp*or*lp*
Upcoming Changes
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• Colors%• Overo*
• Frame*
• Sabino*• Splashed*White*
• Appaloosa*• Champagne*
• Silver*• Pearl*• Dominant*White*
• Lethals%• Punnet%Square%
What’s NOT Covered in This Presentation
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Horse Smarts
hbp://www.ayhc.com/productSpage/horseSsmarts*
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• Will*be*used*at*
2017*Na1onal*
Contests*
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