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1. QTL Analysis: A Robust Method for Uncovering the Genetics of Sleep(and Other Complex Traits)
2. Quantitative Traits Quantitative traits are continuous
Human height, weight, blood pressure, 5-HT levels
Sleep: amount, bout length, onset, REM/NREM
3. Quantitative Traits and QTLs Quantitative traits caused by many genes with small effects
And environment
Gene x environment interactions
Quantitative Trait Loci (QTLs) are regions of the genome associated with a trait: markers, genes, several linked genes, promoters/enhancers
4. Typical QTL Analysis Approach Two strains of a model organism differ with respect to a trait
Intercross or backcross the two strains, genetic recombination creates a normal distribution of the trait in F2s
Measure the trait in the F2s, and genotype the extremes
Use statistical techniques to associate genetic loci with the trait
(Ideally) narrow the loci to individual genes
5. QTL Analysis: Experimental Crosses
6. QTL Analysis: Phenotypes Extremes are most informative
7. QTL Analysis: Genotypes
8. QTL Analysis: Association
9. QTL Analysis: Statistical Methods ANOVA
Interval Mapping
EM algorithm
Haley-Knott regression
Each method computes LOD / LRS scores
log P(H1)/ P(H0)
10. QTL Analysis: LOD Score Significance Threshold
11. QTL Analysis: Results
12. QTL Analysis: Results
13. QTL Analysis Ultimate confirmation is allelic substitution (in vivo) or functional studies (in vitro)
14. Better QTL Analysis: RILs
15. Better QTL Analysis: Collaborative Cross
17. CC: Genetic Diversity
19. Mapping Power of the Collaborative Cross
23. Sleep Phenotype Traditional methods
EEG
EMG/EOG
Wheel running
IR beam breaking
Our method
Piezoelectric motion recording
24. A novel piezoelectric system for sleep characterization Advantages
Cost effective
Non-invasive
High throughput
90-95% accurate against human and EEG scores
Disadvantages:
Requires enormous computational resources to process data
Does not score variables within sleep (REM vs NREM, etc.) at this time
25. Piezoelectric pad
26. Quad cage design
27. Piezo system at ORNL
28. MouseRec signal recording
30. Computer classifier
31. Piezo vs Pneumograph
32. Piezo vs EEG vs EMG
38. Future Work QTL analysis of experimental and baseline recording panels
Fine mapping of QTLs
Identification of genes