Seminar Details

Seminar Details


Dec 15

3:30 pm

Inference of Identity by Descent for Linkage Analysis

Fiona Grimson

Final Exam

Advisor: Professor Elizabeth Thompson

Inference of identity by descent for linkage analysis Identity by descent (IBD) describes the pattern of shared inheritance of DNA among individuals. Two or more copies of DNA are identical by descent if they are inherited from the same common ancestor. IBD underlies the genetic similarity between individuals and thus similarity in observed genetic traits. In a family study of a genetic disease, estimated IBD among individuals in the family is used to identify potential locations of the gene that causes the disease. IBD is estimated among the individuals in the family relative to the founders of the family pedigrees. The founders of the family pedigrees, however, also have common ancestors in the population from which the families are drawn. As these relationships are unknown, they are not reflected in the pedigree IBD estimates. I propose a method for estimating IBD among individuals in family pedigrees relative to common ancestors in the population. The method merges IBD estimates among the pedigree members relative to pedigree founders with estimates of IBD among the pedigree founders relative to the population. The resulting merged IBD increases the power and precision of linkage analyses by identifying shorter segments of potentially causal DNA shared IBD among pedigree founders. The merging method is demonstrated on data from a family study of
Alzheimer's disease.