X monosomy in the endangered Kiso horse breed detected by a parentage test using sex chromosome linked genes and microsatellites

Gamo, Shiori; Tozaki, Teruaki; Kakoi, Hironaga; Hirota, Kei‐ichi; Nakamura, Kotono; Nishii, Noriko; Alumunia, Julio; Takasu, Masaki

doi:10.1292/jvms.18-0253

Cited by 5 publications

(7 citation statements)

References 13 publications

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“…Mares with X monosomy are infertile and have irregular or absent oestrous cycles and small gonads lacking follicular development . Short stature is observed in some cases; however, individuals with normal appearance and normal external female genitalia are also reported . The frequency of X monosomy has been estimated at ~3%, based on cytogenetic screening of 262 young mares .…”

Section: Introductionmentioning

confidence: 99%

“…3 Short stature is observed in some cases; 4 however, individuals with normal appearance and normal external female genitalia are also reported. 5 The frequency of X monosomy has been estimated at ~3%, based on cytogenetic screening of 262 young mares. 6 Another analysis of microsatellite X-linked markers in a population of 17,471 newborn foals suggested that the incidence is much lower, at 0.15%.…”

Section: Introductionmentioning

confidence: 99%

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Application of droplet digital PCR in diagnosing of X monosomy in mares

Szczerbal

Nowacka‐Woszuk

Kopp-Kuhlman³

et al. 2020

Equine Veterinary Journal

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Background X monosomy is the most common disorder of sex development in horses. Although cytogenetic analysis is still the gold standard in the diagnosis of equine X monosomy, novel molecular techniques are being sought to quickly and reliably detect this chromosome abnormality. Objectives The goal of this study was to evaluate the usefulness of a novel variant of the PCR technique—namely, droplet digital PCR (ddPCR)—in the detection of X monosomy in mares. Study design A proof of concept of the usefulness of ddPCR in diagnosing an abnormal number of X chromosomes in mares. Methods We examined an infertile mare using cytogenetic (fluorescent in situ hybridisation—FISH) and molecular (droplet digital PCR—ddPCR) techniques. The X chromosome copy number in ddPCR was estimated via detection of the AMELX gene copy number. In addition, 70 mares homozygous for X‐linked microsatellite marker (LEX3) were examined by ddPCR. For all mares, a PCR search for the Y‐linked SRY gene was also performed. Results Cytogenetic analysis and ddPCR gave concordant results, indicating pure X monosomy in the studied mare. Of the 70 additional mares examined by ddPCR, a single copy of the X chromosome was found in two cases. All mares were SRY‐negative and thus both freemartinism, manifested by leucocyte XX/XY chimerism, and sex reversal syndrome (XX, SRY‐positive) could be excluded. Main limitations The ddPCR approach does not allow for unequivocal identification of mosaicism (63,X/64,XX or 65,XXX/64,XX), but may give an indication that further cytogenetic analysis is necessary. Conclusion The ddPCR approach appeared to be useful for diagnosing nonmosaic X monosomy in mares. If the number of X chromosome copies in a mare, as determined by ddPCR, differs from two (in our study, <1.8 or >2.2), additional cytogenetic investigation is recommended with the aim of detecting the mosaicism.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Application of droplet digital PCR in diagnosing of X monosomy in mares

Szczerbal

Nowacka‐Woszuk

Kopp-Kuhlman³

et al. 2020

Equine Veterinary Journal

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“…The International Society of Animal Genetics (ISAG) recommends the use of a properly standardized panel of 17 microsatellite markers for horses, located on 12 different autosomes and the X chromosome. By adding to this set additional X and Y chromosome markers, whole-genome STR genotyping for parentage testing can simultaneously be used for the initial detection of chromosomal aberrations, such as monosomy, trisomy, XY sex reversal syndrome and chimerism [ 53 , 126 , 127 , 194 , 195 , 196 ]. Microsatellite genotyping has also been used to determine the parental origin of an aberrant chromosome [ 27 , 197 ] and in a study of two cloned horses, one with a de novo autosomal translocation, to confirm that the clones and their sire were genetically identical [ 54 ].…”

Section: Molecular Cytogenetic Methods and Applicationsmentioning

confidence: 99%

Horse Clinical Cytogenetics: Recurrent Themes and Novel Findings

Bugno‐Poniewierska

Raudsepp

2021

Animals

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Clinical cytogenetic studies in horses have been ongoing for over half a century and clearly demonstrate that chromosomal disorders are among the most common non-infectious causes of decreased fertility, infertility, and congenital defects. Large-scale cytogenetic surveys show that almost 30% of horses with reproductive or developmental problems have chromosome aberrations, whereas abnormal karyotypes are found in only 2–5% of the general population. Among the many chromosome abnormalities reported in the horse, most are unique or rare. However, all surveys agree that there are two recurrent conditions: X-monosomy and SRY-negative XY male-to-female sex reversal, making up approximately 35% and 11% of all chromosome abnormalities, respectively. The two are signature conditions for the horse and rare or absent in other domestic species. The progress in equine genomics and the development of molecular tools, have qualitatively improved clinical cytogenetics today, allowing for refined characterization of aberrations and understanding the underlying molecular mechanisms. While cutting-edge genomics tools promise further improvements in chromosome analysis, they will not entirely replace traditional cytogenetics, which still is the most straightforward, cost-effective, and fastest approach for the initial evaluation of potential breeding animals and horses with reproductive or developmental disorders.

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“…Fifteen years later, Power [ 34 ] reported up to 400 individuals carrying CNAs, of which over 95% were related to fertility problems. Thirty years later, it became clear that ECAX monosomy, in its true (63,X; [ 35 ]) or 64,XX/63,X mosaic [ 36 ] forms, together with 64,XYdsd sex reversal mares [ 19 ], are the most common presentations in the species. Both cases are associated with a normal mare phenotype with a lack of development of the internal reproductive organs [ 37 ].…”

Section: Copy Number Abnormalities and Fertility: The Role Of The mentioning

confidence: 99%

Impaired Reproductive Function in Equines: From Genetics to Genomics

Laseca

Anaya

Peña

et al. 2021

Animals

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Fertility is one of the key factors in the economic and productive success of the equine industry. Despite this, studies on the genetic causes affecting reproductive performance are scarce, especially in mares, where the genetic architecture of the reproductive traits is extremely complex. Today, with the increasing availability of new genomic methodologies for this species, we are presented with an interesting opportunity to understand the genetic basis of equine reproductive disorders. These include, among others, novel techniques for detecting chromosomal abnormalities, whose association with infertility in horses was established over 50 years ago; new sequencing technologies permitting an accurate detection of point mutations influencing fertility, as well as the study of inbreeding and molecular homozygosity, which has been widely suggested as one of the main causes of low reproductive performance in horses. Finally, over the last few years, reproductive performance has also been associated with copy number variants and candidate genes detected by genome-wide association studies on fertility traits. However, such studies are still scarce, probably because they depend on the existence of large and accurate phenotypic datasets of reproductive and/or fertility traits, which are still difficult to obtain in equines.

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X monosomy in the endangered Kiso horse breed detected by a parentage test using sex chromosome linked genes and microsatellites

Cited by 5 publications

References 13 publications

Application of droplet digital PCR in diagnosing of X monosomy in mares

Application of droplet digital PCR in diagnosing of X monosomy in mares

Horse Clinical Cytogenetics: Recurrent Themes and Novel Findings

Impaired Reproductive Function in Equines: From Genetics to Genomics

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