Chromosome Abnormalities in Domestic Animals as Causes of Disorders of Sex Development or Impaired Fertility

Equine Veterinary Journal

Nowacka‐Woszuk

Kopp-Kuhlman³

et al. 2020

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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.

Section: Introductionmentioning

confidence: 99%

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

Equine Veterinary Journal

Nowacka‐Woszuk

Kopp-Kuhlman³

et al. 2020

Self Cite

“…Disorders of sex development (DSDs) are responsible for sterility or infertility among domestic animals (Szczerbal & Switonski, ). These disorders can be caused by gene mutations or chromosome anomalies, as well as by other factors, such as placental anastomosis of heterosexual fetuses.…”

Section: Introductionmentioning

confidence: 99%

Disorders of sex development in cats with different complements of sex chromosomes

Reprod Domestic Animals

Krzemińska

Dzimira

et al. 2018

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The genetic background of disorders of sex development (DSDs) in cats is poorly understood, due to a relatively low number of such studies in this species. Here we present three new DSD cases with different complements of sex chromosomes. The first, an Oriental Shorthair cat with a rudimentary penis, abdominal atrophic testicles and lack of uterus appeared to be a freemartin, since leucocyte chimerism XX/XY and a lack of Y-linked genes (SRY and ZFY) were observed in DNA isolated from hair follicles. XXY trisomy was identified in the second case, a tortoiseshell Devon Rex male cat with atrophic scrotal testicles and a normal penis. Finally, a European Shorthair cat with atrophic testicles in a bifid scrotum, rudimentary penis and a lack of uterus had XY complement, including Y chromosome of normal size and morphology. Also presence of eight Y-linked genes, detected by PCR, was confirmed. Due to the low testosterone level in this last patient, we searched for a causative mutation in two candidate genes (HSD3B2 and HSD17B3) involved in the metabolism of this steroid hormone. Altogether, five polymorphic sites in HSD3B2 and two in HSD17B3 were found, but none of them showed associations with DSD phenotype. We thus excluded a possibility that the causative mutation is present in these genes. In conclusion, we confirmed that analysis of the sex chromosome complement is a crucial step in diagnosis of DSDs. However, extensive molecular studies of the genes involved in sex development are needed to elucidate the causes of DSDs in cats with normal complements of sex chromosomes.

“…The DSD are an important breeding issue, as they affect reproduction, and in case of their hereditary forms, a wide spreading of the undesired mutations may occur. Thus, the extensive studies of the genetic background of such disorders have been conducted in domestic animals (Meyers‐Wallen, ; Parma, Veyrunes, & Pailhoux, ; Raudsepp & Chowdhary, ; Szczerbal & Switonski, ). Nevertheless, structural rearrangements involving sex chromosomes were rarely reported in companion species.…”

Section: Discussionmentioning

confidence: 99%

“…Disorders of sex development (DSD), defined as a condition where chromosomal, gonadal or phenotypic sex is atypical, are a wellknown problem in domestic animal reproduction (Szczerbal & Switonski, 2016). Three main categories of DSD are distinguished as follows: sex chromosome DSD, XX DSD and XY DSD (Meyers-Wallen, 2012).…”

Section: Introductionmentioning

confidence: 99%

Disorder of sex development in a cat with chromosome mosaicism 37,X/38,X,r(Y)

Reprod Domestic Animals

Stachowiak

Nowacka‐Woszuk

et al. 2017

An 18-month-old European shorthair cat was subjected to genetic studies due to ambiguous external genitalia (underdeveloped both penis and scrotum). Further anatomic and histopathological studies revealed the presence of abdominal, atrophic testes and uterus. Cytogenetic analysis showed two cell lines, one with X monosomy-37,X [90% of the analysed metaphase spreads], and other line had 38 chromosomes with normal X chromosome and abnormally small Y-derived chromosome-38,X,der(Y) [10%]. Further fluorescence in situ hybridization study with telomeric probe revealed a ring structure of the der(Y). Eight Y chromosome-specific genes, SRY, TETY1, TETY2, CUL4BY, CYORF15, HSFY, FLJ36031Y and ZFY, were detected. We conclude that the described abnormality of the reproductive system, leading to sterility, was caused by a very rare type of chromosomal mosaicism-37,X/38,X,r(Y).