Download Slide 1

Utilizing DNA testing in identifying
multiple gene traits
Prof Norman Maiwashe1,2 (PhD, Pri Sci Nat)
1ARC-Animal
Production Institute
Animal Breeding and Genetics
Private Bag X2, Irene, 0062
2 Dept.
of Animal, Wildlife and Grassland Sciences
University of the Free State
Bloemfontein, 9300
Stud Game Industry Workshop – 15 March 2013 – Bela-Bela
Off with a disclaimer
• I am a livestock geneticist and therefore do
not claim any expertise about game
• BUT, I think we can compare notes
• Genetics is genetics anyway
The purpose of presentation
• To highlight the importance of phenotypic and
DNA data as raw materials for application of
biotechnology in genetic improvement
programmes
Presentation Outline
1.
Genetics of complex traits
2.
Genetics versus environment
3.
Horn length: A Soay Sheep example
4.
Using DNA in selection for complex traits
5.
Concluding Remarks
What are complex traits?
 These are traits or characteristics influenced by:
 multiple genes and
 often by the environment
P=G+E
 Distinguishing genetic from environmental
effects is therefore difficult
 Improvement of these traits through selection is
a challenge
 A good phenotype does not necessarily mean
good genetics and vice versa
Genetics versus Environment
 Heritability provides an indication of the
proportion of the total variation that is due to
genetics
 Example Trait: horn length
 Has a heritability of 33% in Soay Sheep
 Thus, environment account for 67% of the variation
in horn length
 It can be concluded that horn length is under
genetic control
 Question?
 How many genes are involved?
Using DNA to find genes or markers
 Genetic markers
 Part of DNA that does not affect the trait
 Widespread in the genome
 Easy to stumble on a genetic marker than a gene
 Large numbers of genetic markers (SNPs)
have been discovered recently
 Since some of these markers are in close proximity to genes,
markers can be used as proxies (indicators) for genes
 We have been quite successful in finding
genetic markers but not the genes
themselves
Genetic markers for horn length
• Soay sheep:
– Genetic marker or region in DNA associated with
horn length found in Chromosome 1 (Johnston et al., 2010)
– Differences in this piece of DNA explains almost all
the genetic variation (additive ) in horn length
• What does this mean?
– Genetic markers can be used to select for horn
length
Finding genetic markers and using them
• What is required?
– Discovery population of animals
• Phenotypic data (measurements)
• Genotypic data on genetic markers (DNA)
– Validation population
• The associations between phenotypes and genotypes
should be validated in independent populations
(validation)
• Once the genetic markers are identified and validated
genetic tests are commercialised
How does it work in practice?
1. Collected biological sample
–
Hair, blood, etc.
2. Send the sample to the laboratory
3. DNA extraction and sample analyses
4. Report on the genetic status sent back to farm
5. Information used for selection
What should the game industry do to
benefit from DNA technology?
• Set-up a programme for:
– Data collection on traits of economic importance
– Collection of biological samples
• Invest in R & D
– In genetics underlying expression of phenotypes
– In biotechnology
Summary
• Our knowledge of genetics underlying
important traits in game species is at its
infancy
• The game industry is well-positioned to
provide leadership in R & D in game species
– Investment in R & D would ensure long-term sustainability of
the game industry
• The ARC is committed to positively contribute
to R & D efforts for the benefit of the game
industry
Thanks For You Attention