Identity by descent
Encyclopedia
Two or more alleles are identical by descent (IBD) if they are identical copies of the same ancestral allele. This property is often used in genetic linkage
to identify alleles which are potential candidates for harboring mutations causing a genetic disease.
A common way to identify alleles as identical by descent is usually carried using single-nucleotide polymorphism (SNP) data. If enough SNP in two alleles are observed as the same, then the two alleles are inferred as IBD. Although this does not guarantee that the two alleles are identical. Even if they are indeed derived from the same ancestral allele, they could harbor different mutations which arose during the inheritance process, like single nucleotide mutations, insertion, deletions or others.
Given the new importance that IBD alleles are assuming in genetic association studies
, a new definition of IBD that would better suit the underlying inheritance property would be that two or more alleles are be identical by descent (IBD) if they have been inherited from the same ancestral allele without recombination
events.
Genetic linkage
Genetic linkage is the tendency of certain loci or alleles to be inherited together. Genetic loci that are physically close to one another on the same chromosome tend to stay together during meiosis, and are thus genetically linked.-Background:...
to identify alleles which are potential candidates for harboring mutations causing a genetic disease.
A common way to identify alleles as identical by descent is usually carried using single-nucleotide polymorphism (SNP) data. If enough SNP in two alleles are observed as the same, then the two alleles are inferred as IBD. Although this does not guarantee that the two alleles are identical. Even if they are indeed derived from the same ancestral allele, they could harbor different mutations which arose during the inheritance process, like single nucleotide mutations, insertion, deletions or others.
Given the new importance that IBD alleles are assuming in genetic association studies
Genetic association
Genetic association is the occurrence, more often than can be readily explained by chance, of two or more traits in a population of individuals, of which at least one trait is known to be genetic....
, a new definition of IBD that would better suit the underlying inheritance property would be that two or more alleles are be identical by descent (IBD) if they have been inherited from the same ancestral allele without recombination
Genetic recombination
Genetic recombination is a process by which a molecule of nucleic acid is broken and then joined to a different one. Recombination can occur between similar molecules of DNA, as in homologous recombination, or dissimilar molecules, as in non-homologous end joining. Recombination is a common method...
events.