Identical-by-descent: Identical copies of an allele or segment of DNA that two individuals have inherited from a shared common ancestor.
In this work, we use the term Identity By Descent or Identical By Descent (IBD) to refer to genomic regions inherited from the Most Recent Common Ancestors (MRCAs) of the two individuals.
Here we report the further linkage analysis of this family and a second family of Northern European descent segregating an identical phenotype.
The consequence of common ancestry is that large genomic intervals are identical by descent, resulting in reduced genetic diversity.
As modelled here, the conditional covariance of two gametic effects depends on the event that they are identical by descent in the observed pedigree.
The expected additive genetic relationships (genetic covariances) derived from a pedigree are based on probabilities that gene pairs are identical by descent (IBD) (Lynch and Walsh 1998).
The logic behind our approach is that rare susceptibility variants should be found more often on regions shared identical by descent by affected sibling pairs than on regions not shared identical by descent.
Typically, F, defined as the probability that both alleles at any locus within an individual are identical by descent (IBD), has been computed from pedigree information.
This study encompassed populations with a degree of shared ancestry, which enabled the evaluation of resistance alleles that were identical by descent (IBD) in different populations and experiments.
The most likely explanation for this pattern is recent common ancestry, such that the mapping parents sometimes shared genomic regions that were identical by descent.
For the same reason, opposite-sex sibling pairs will share fewer alleles identical by descent.
