The effect of consanguinity on coalescence times on the X chromosome

Cotter, Daniel J.; Severson, Alissa L.; Rosenberg, Noah A.

doi:10.1016/j.tpb.2021.03.004

Cited by 6 publications

(28 citation statements)

References 25 publications

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“…Appendix C: Limiting distribution of autosomal coalescence times for first-cousin mating Equation 46 of Severson et al (2021) gives a limiting distribution of autosomal coalescence times for a model with a superposition of levels of cousin mating, up to nth cousins. In order to recover first-cousin mating on the autosomes to compare to our X-chromosomal results, we use the special case of this nth cousin model, where the rate of sibling mating c 0 is 0 and the rate of first-cousin mating is c 1 , stopping at first cousins.…”

Section: Discussionmentioning

confidence: 99%

“…We extract from the first column of this matrix the cumulative distribution functions for two lineages starting in state 1 (within an individual) and state 3 (between individuals): Severson et al (2021) showed that the limiting distribution for nth cousin mating is given by their Eqs. 47 and 48:…”

Section: Discussionmentioning

confidence: 99%

“…To analyze the large-N limit of the model, we make use of the separation-of-time-scales approach introduced by Möhle (1998). This approach was used by Severson et al (2021) to obtain the limiting distribution of coalescence times under their autosomal diploid model of consanguinity. In the approach from Möhle (1998), the limiting distribution of a Markov process with transition matrix Π N is obtained by writing…”

Section: Methodsmentioning

confidence: 99%

“…Here, we use the advance from Severson et al . (2021) to compute the full distribution of coalescence times under a diploid, two-sex consanguinity model (Cotter et al ., 2021). Seeking to derive distributions of X-chromosomal coalescence times, we consider each of the six types of first-cousin consanguinity and a model that includes all four unilateral types in a single population.…”

Section: Introductionmentioning

confidence: 99%

“…Severson et al (2021) sex-specific varieties of consanguinity at different levels of relationship. transient states.…”

mentioning

confidence: 99%

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Limiting distribution of X-chromosomal coalescence times under first-cousin consanguineous mating

Cotter¹,

Severson²,

Carmi

et al. 2022

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By providing additional opportunities for coalescence within families, the presence of consanguineous unions in a population reduces coalescence times relative to non-consanguineous populations. First-cousin consanguinity can take one of six forms differing in the configuration of sexes in the pedigree of the male and female cousins who join in a consanguineous union: patrilateral parallel, patrilateral cross, matrilateral parallel, matrilateral cross, bilateral parallel, and bilateral cross. Considering populations with each of the six types of first-cousin consanguinity individually and a population with a mixture of the four unilateral types, we examine coalescent models of consanguinity. We previously computed, for first-cousin consanguinity models, the mean coalescence time for X-chromosomal loci and the limiting distribution of coalescence times for autosomal loci. Here, we use the separation-of-time-scales approach to obtain the limiting distribution of coalescence times for X-chromosomal loci. This limiting distribution has an instantaneous coalescence probability that depends on the probability that a union is consanguineous; lineages that do not coalesce instantaneously coalesce according to an exponential distribution. We study the effects on the coalescence time distribution of the type of first-cousin consanguinity, showing that patrilateral-parallel and patrilateral-cross consanguinity have no effect on X-chromosomal coalescence time distributions and that matrilateral-parallel consanguinity decreases coalescence times to a greater extent than does matrilateral-cross consanguinity.

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%