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The Effect of Consanguinity on Between-Individual Identity-by-Descent Sharing

Consanguineous unions increase the rate at which identical genomic segments are paired within individuals to produce runs of homozygosity (ROH). The extent to which such unions affect identity-by-descent (IBD) genomic sharing between rather than within individuals in a population, however, is not im...

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Autores principales: Severson, Alissa L., Carmi, Shai, Rosenberg, Noah A.
Formato: Online Artículo Texto
Lenguaje:English
Publicado: Genetics Society of America 2019
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6499533/
https://www.ncbi.nlm.nih.gov/pubmed/30926583
http://dx.doi.org/10.1534/genetics.119.302136
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author Severson, Alissa L.
Carmi, Shai
Rosenberg, Noah A.
author_facet Severson, Alissa L.
Carmi, Shai
Rosenberg, Noah A.
author_sort Severson, Alissa L.
collection PubMed
description Consanguineous unions increase the rate at which identical genomic segments are paired within individuals to produce runs of homozygosity (ROH). The extent to which such unions affect identity-by-descent (IBD) genomic sharing between rather than within individuals in a population, however, is not immediately evident from within-individual ROH levels. Using the fact that the time to the most recent common ancestor [Formula: see text] for a pair of genomes at a specific locus is inversely related to the extent of IBD sharing between the genomes in the neighborhood of the locus, we study IBD sharing for a pair of genomes sampled either within the same individual or in different individuals. We develop a coalescent model for a set of mating pairs in a diploid population, treating the fraction of consanguineous unions as a parameter. Considering mating models that include unions between sibs, first cousins, and nth cousins, we determine the effect of the consanguinity rate on the mean [Formula: see text] for pairs of lineages sampled either within the same individual or in different individuals. The results indicate that consanguinity not only increases ROH sharing between the two genomes within an individual, it also increases IBD sharing between individuals in the population, the magnitude of the effect increasing with the kinship coefficient of the type of consanguineous union. Considering computations of ROH and between-individual IBD in Jewish populations whose consanguinity rates have been estimated from demographic data, we find that, in accord with the theoretical results, increases in consanguinity and ROH levels inflate levels of IBD sharing between individuals in a population. The results contribute more generally to the interpretation of runs of homozygosity, IBD sharing between individuals, and the relationship between ROH and IBD.
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spelling pubmed-64995332019-05-24 The Effect of Consanguinity on Between-Individual Identity-by-Descent Sharing Severson, Alissa L. Carmi, Shai Rosenberg, Noah A. Genetics Investigations Consanguineous unions increase the rate at which identical genomic segments are paired within individuals to produce runs of homozygosity (ROH). The extent to which such unions affect identity-by-descent (IBD) genomic sharing between rather than within individuals in a population, however, is not immediately evident from within-individual ROH levels. Using the fact that the time to the most recent common ancestor [Formula: see text] for a pair of genomes at a specific locus is inversely related to the extent of IBD sharing between the genomes in the neighborhood of the locus, we study IBD sharing for a pair of genomes sampled either within the same individual or in different individuals. We develop a coalescent model for a set of mating pairs in a diploid population, treating the fraction of consanguineous unions as a parameter. Considering mating models that include unions between sibs, first cousins, and nth cousins, we determine the effect of the consanguinity rate on the mean [Formula: see text] for pairs of lineages sampled either within the same individual or in different individuals. The results indicate that consanguinity not only increases ROH sharing between the two genomes within an individual, it also increases IBD sharing between individuals in the population, the magnitude of the effect increasing with the kinship coefficient of the type of consanguineous union. Considering computations of ROH and between-individual IBD in Jewish populations whose consanguinity rates have been estimated from demographic data, we find that, in accord with the theoretical results, increases in consanguinity and ROH levels inflate levels of IBD sharing between individuals in a population. The results contribute more generally to the interpretation of runs of homozygosity, IBD sharing between individuals, and the relationship between ROH and IBD. Genetics Society of America 2019-05 2019-03-28 /pmc/articles/PMC6499533/ /pubmed/30926583 http://dx.doi.org/10.1534/genetics.119.302136 Text en Copyright © 2019 by the Genetics Society of America Available freely online through the author-supported open access option.
spellingShingle Investigations
Severson, Alissa L.
Carmi, Shai
Rosenberg, Noah A.
The Effect of Consanguinity on Between-Individual Identity-by-Descent Sharing
title The Effect of Consanguinity on Between-Individual Identity-by-Descent Sharing
title_full The Effect of Consanguinity on Between-Individual Identity-by-Descent Sharing
title_fullStr The Effect of Consanguinity on Between-Individual Identity-by-Descent Sharing
title_full_unstemmed The Effect of Consanguinity on Between-Individual Identity-by-Descent Sharing
title_short The Effect of Consanguinity on Between-Individual Identity-by-Descent Sharing
title_sort effect of consanguinity on between-individual identity-by-descent sharing
topic Investigations
url https://www.ncbi.nlm.nih.gov/pmc/articles/PMC6499533/
https://www.ncbi.nlm.nih.gov/pubmed/30926583
http://dx.doi.org/10.1534/genetics.119.302136
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