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Mendel-Penetrance Module Presenter: Joseph Kim Mentors: Dr.Kenneth Lange Brian Dolan
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What is Mendel? Software package Performs statistical analysis to solve a variety of genetic problems http://www.biomath.medsch.ucla.edu/faculty/kla nge/software.html
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Goal Beta test Mendel’s new Penetrance module Methods: Find data pertaining to penetrance Plug data into Mendel See if results agree with already established results
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Penetrance Our definition: the statistical relationship between genotype and phenotype; the likelihood of the phenotype given the genotype
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Incomplete Penetrance-Example not x-linked (male to male transmission) Incompletely dominant II-1 not affected *color reflects phenotype, not genotype http://www.uic.edu/classes/bms/bms655/lesson4.html
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Mendel-Penetrance Module Statistically models penetrance of alleles using pedigree data Outputs parameters of the fitted model such as μ and σ (normal distribution)
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Motivation The output of Mendel can be used for finding disease genes by linkage analysis and association analysis “Increase power of genetic analysis” – Brian Dolan Mendel can be used to determine who’s at risk of being affected with the genetic disease
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Why is Mendel Better? More versatile statistical models and a better ascertainment correction Commercial software assume that the observations are independent Better trait models enable better mapping of disease and trait genes
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Background-Likelihood Lange, Kenneth. Mathematical and Statistical Methods L: the likelihood of the pedigree data n:number of people Xi:phenotype of ith person Gi:possible genotype of ith person product on j is taken over all founders product on {k,l,m} is taken over all parent-offspring triples
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Background-Pen Function Contains all parameters to be optimized Example: Probability Density Function N(μ,σ ) http://en.wikipedia.org/wiki/Normal_distribution
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Generalized Linear Models (GLM) Normal Distribution is not sufficient Incorporate other GLM to overcome deficiencies in the normal distribution Binomial Poisson Exponential Gamma Inverse Normal Lognormal
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Background-Prior Function The frequencies of genotypes in population Typically incorporate Hardy-Weinberg genotype frequencies Assume different loci are independent Ex: For two locus trait A/a and B/b, P(A,b)=P(A)P(b)
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Background-Tran Function Punnett Square
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Optimization Maximize L with respect to parameters Only concerned with parameters in Penetrance function Use Lagrange multipliers to limit values of parameters Use iterative methods to solve for the parameters
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http://www.ecs.umass.edu/mie/labs/injection/research/process/
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Distribution of Phenotypes The values in the population fit a continuous distribution. Courtesy of Dr. Janet Sinsheimer
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http://en.wikipedia.org/wiki/Normal_distribution Different curves have different parameters Mendel will fit and give parameters for distribution of given data
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Input files Initialize Parameters θ 0 Calculate L under θ m Find θ m+1 that increases L Output files Repeat until convergence
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Mendel Files Input files: Control.in Ped.in Locus.in Map.in Var.in Output file: Mendel.out
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Mendel.out
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What Do the Numbers Mean? Parameters define the probability distribution function of the penetrance; it is a property of the penetrance of the trait Knowing the parameters will allow more accurate results for research that requires knowledge in these properties (i.e. formulas that depend on these values)
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Results Verified the program using large pedigree segregating high triglycerides Bugs found: 1 Default Scaling factor causing underflow (Truncation Error) resulting in early termination of the iterations
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Acknowledgements Dr. Kenneth Lange Brian Dolan Dr. Janet Sinsheimer Lara Bauman Dr.Sharp and Dr.Johnston Dr. Richard Johnston Socalbsi
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Bibliography http://www.uic.edu/classes/bms/bms655/lesson4.html http://www.uic.edu/classes/bms/bms655/lesson4.html Sobel E, Papp JC, Lange, K. “Detection and integration of genotyping errors in statistical genetics” Am J Hum Genet. 2002 Feb;70(2):496-508. Epub 2002 Jan 8. PMID: 11791215 Lange, Kenneth. Optimization. Springer-Verlag NY, LLC. New York: 2004. Lange, Kenneth. Mathematical and Statistical Methods for Genetic Analysis. Second Edition. Springer-Verlag New York, Inc. New York: 2002. Sinsheimer, Janet. Quantitative Traits slides http://en.wikipedia.org/wiki/Normal_distribution http://en.wikipedia.org/wiki/Normal_distribution http://www.ecs.umass.edu/mie/labs/injection/research/process/
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