Gene Conversion between the X Chromosome and the Male-Specific Region of the Y Chromosome at a Translocation Hotspot

Rosser, Zoë H.; Balaresque, Patricia; Jobling, Mark A.

doi:10.1016/j.ajhg.2009.06.009

Cited by 74 publications

(68 citation statements)

References 21 publications

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“…They would not be expected if recombination stopped due to an event in the genome region affected (e.g., an inversion causing Y linkage of a PAR haplotype of the region), because diversity in the Y would be eliminated in the resulting selective sweep. However, the X-and Y-linked alleles could still recombine in regions away from inversion breakpoints, through double crossovers or by gene conversion, which has been documented in the male-specific regions of mammalian sex chromosome pairs (Slattery et al 2000;Rosser et al 2009;Trombetta et al 2010;Ellegren 2011), particularly in the moderately recent stratum 4 (Iwase et al 2010). However, the locations of the shared polymorphisms are not clustered, and do not suggest gene conversion.…”

Section: Population Genetic Tests Of Par Locations Of Candidate Par Gmentioning

confidence: 94%

Testing for the Footprint of Sexually Antagonistic Polymorphisms in the Pseudoautosomal Region of a Plant Sex Chromosome Pair

Qiu¹,

Bergero²,

Charlesworth

2013

Genetics

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The existence of sexually antagonistic (SA) polymorphism is widely considered the most likely explanation for the evolution of suppressed recombination of sex chromosome pairs. This explanation is largely untested empirically, and no such polymorphisms have been identified, other than in fish, where no evidence directly implicates these genes in events causing loss of recombination. We tested for the presence of loci with SA polymorphism in the plant Silene latifolia, which is dioecious (with separate male and female individuals) and has a pair of highly heteromorphic sex chromosomes, with XY males. Suppressed recombination between much of the Y and X sex chromosomes evolved in several steps, and the results in Bergero et al. (2013) show that it is still ongoing in the recombining or pseudoautosomal, regions (PARs) of these chromosomes. We used molecular evolutionary approaches to test for the footprints of SA polymorphisms, based on sequence diversity levels in S. latifolia PAR genes identified by genetic mapping. Nucleotide diversity is high for at least four of six PAR genes identified, and our data suggest the existence of polymorphisms maintained by balancing selection in this genome region, since molecular evolutionary (HKA) tests exclude an elevated mutation rate, and other tests also suggest balancing selection. The presence of sexually antagonistic alleles at a locus or loci in the PAR is suggested by the very different X and Y chromosome allele frequencies for at least one PAR gene.

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Section: Population Genetic Tests Of Par Locations Of Candidate Par Gmentioning

confidence: 94%

Testing for the Footprint of Sexually Antagonistic Polymorphisms in the Pseudoautosomal Region of a Plant Sex Chromosome Pair

Qiu¹,

Bergero²,

Charlesworth

2013

Genetics

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“…1 In fact, in most XX males, SRY is transposed to the tip of Xp as a consequence of a recurrent Xp;Yp translocation, arising predominantly by nonallelic homologous recombination between PRKX and PRKY on a particular Y haplotypic background. 2,3 These males, usually with small testes, are essentially picked up among men with nonobstructive azoospermia.…”

Section: Introductionmentioning

confidence: 99%

Testis development in the absence of SRY: chromosomal rearrangements at SOX9 and SOX3

et al. 2014

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Duplications in the~2 Mb desert region upstream of SOX9 at 17q24.3 may result in familial 46,XX disorders of sex development (DSD) without any effects on the XY background. A balanced translocation with its breakpoint falling within the same region has also been described in one XX DSD subject. We analyzed, by conventional and molecular cytogenetics, 19 novel SRY-negative unrelated 46,XX subjects both familial and sporadic, with isolated DSD. One of them had a de novo reciprocal t(11;17) translocation. Two cases carried partially overlapping 17q24.3 duplications~500 kb upstream of SOX9, both inherited from their normal fathers. Breakpoints cloning showed that both duplications were in tandem, whereas the 17q in the reciprocal translocation was broken at~800 kb upstream of SOX9, which is not only close to a previously described 46,XX DSD translocation, but also to translocations without any effects on the gonadal development. A further XX male, ascertained because of intellectual disability, carried a de novo cryptic duplication at Xq27.1, involving SOX3. CNVs involving SOX3 or its flanking regions have been reported in four XX DSD subjects. Collectively in our cohort of 19 novel cases of SRY-negative 46,XX DSD, the duplications upstream of SOX9 account for~10.5% of the cases, and are responsible for the disease phenotype, even when inherited from a normal father. Translocations interrupting this region may also affect the gonadal development, possibly depending on the chromatin context of the recipient chromosome. SOX3 duplications may substitute SRY in some XX subjects. European Journal of Human Genetics (2015) 23, 1025-1032; doi:10.1038/ejhg.2014.237; published online 5 November 2014 INTRODUCTION 46,XX disorders of sex development (DSDs) are congenital conditions in which, in the presence of a female karyotype, the development of gonadal and anatomical sex is atypical, ranging from various degrees of ambiguous genitalia to phenotypic males with azoospermia. These conditions are poorly characterized, at least in subjects whose DNA does not contain SRY, the gene triggering testis differentiation in mammals. 1 In fact, in most XX males, SRY is transposed to the tip of Xp as a consequence of a recurrent Xp;Yp translocation, arising predominantly by nonallelic homologous recombination between PRKX and PRKY on a particular Y haplotypic background. 2,3 These males, usually with small testes, are essentially picked up among men with nonobstructive azoospermia.A much less well-understood category is that of the 46,XX DSDs negative for SRY. Recently, six of these cases have been reported

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“…Throughout this article, we ignore the pseudoautosomal region(s) (PAR) of the X chromosome, which undergoes crossing over with the Y chromosome in males (Koller and Darlington 1934) to ensure proper disjunction in meiosis I (Hassold et al 1991). We also ignore gene conversion that is known to occur on the X (Rosser et al 2009). …”

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confidence: 99%

A Genealogical Look at Shared Ancestry on the X Chromosome

2016

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Close relatives can share large segments of their genome identical by descent (IBD) that can be identified in genome-wide polymorphism data sets. There are a range of methods to use these IBD segments to identify relatives and estimate their relationship. These methods have focused on sharing on the autosomes, as they provide a rich source of information about genealogical relationships. We hope to learn additional information about recent ancestry through shared IBD segments on the X chromosome, but currently lack the theoretical framework to use this information fully. Here, we fill this gap by developing probability distributions for the number and length of X chromosome segments shared IBD between an individual and an ancestor k generations back, as well as between half-and full-cousin relationships. Due to the inheritance pattern of the X and the fact that X homologous recombination occurs only in females (outside of the pseudoautosomal regions), the number of females along a genealogical lineage is a key quantity for understanding the number and length of the IBD segments shared among relatives. When inferring relationships among individuals, the number of female ancestors along a genealogical lineage will often be unknown. Therefore, our IBD segment length and number distributions marginalize over this unknown number of recombinational meioses through a distribution of recombinational meioses we derive. By using Bayes' theorem to invert these distributions, we can estimate the number of female ancestors between two relatives, giving us details about the genealogical relations between individuals not possible with autosomal data alone.

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Gene Conversion between the X Chromosome and the Male-Specific Region of the Y Chromosome at a Translocation Hotspot

Cited by 74 publications

References 21 publications

Testing for the Footprint of Sexually Antagonistic Polymorphisms in the Pseudoautosomal Region of a Plant Sex Chromosome Pair

Testing for the Footprint of Sexually Antagonistic Polymorphisms in the Pseudoautosomal Region of a Plant Sex Chromosome Pair

Testis development in the absence of SRY: chromosomal rearrangements at SOX9 and SOX3

A Genealogical Look at Shared Ancestry on the X Chromosome

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