----------------------------------------------------------------------- BIOINFORMATICS COLLOQUIUM College of Science George Mason University ----------------------------------------------------------------------- Hidden Markov Models for the Assessment of Chromosomal Alterations using High-throughput SNP Arrays Ingo Ruczinski Johns Hopkins Abstract: Many chromosomal alterations such as amplifications and deletions have been associated with disease. For the genome-wide assessment of such alterations, high-throughput single nucleotide polymorphism (SNP) arrays are often used, estimating DNA copy number and genotypes at up to 1 million loci. Hidden Markov Models (HMMs) are particularly useful for inferring chromosomal alterations from SNP array data, modeling the spatial dependence between neighboring SNPs. We propose a novel HMM for the assessment of the underlying chromosomal states, simultaneously integrating copy number estimates, genotype calls, and the corresponding measures of uncertainty when available. We also show how parent-of-origin effects can be assessed in family data, and discuss the publicly available software packages we have developed.