Equine Disorders of Sexual Development in 17 Mares Including XX, &lt;i&gt;SRY&lt;/i&gt;-Negative, XY, &lt;i&gt;SRY&lt;/i&gt;-Negative and XY, &lt;i&gt;SRY&lt;/i&gt;-Positive Genotypes

Villagómez, D.A.F.; Lear, Teri L.; Chenier, Tracey; Lee, S; McGee, R B; Cahill, Jodi M; Foster, Robert A.; Reyes, E R; John, Elizabeth St.; King, W.A.

doi:10.1159/000322811

Cited by 44 publications

(69 citation statements)

References 105 publications

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“…Further studies investigating isozyme expression of 5α-reductases in other accessory sex glands are necessary to determine the patterns and relative levels in the male reproductive tract of the horse. This information may help in distinguishing among or interpreting the phenotypes and genetic defects associated with male pseudohermaphroditism in horses, which have been far less extensively described or properly characterized (Lear & McGee 2012) than have karyotypic abnormalities or cases of sex reversal (Villagomez et al 2011. Defects in the androgen receptor gene associated with suspected androgen insensitivity syndrome have been reported in stallions (Revay et al 2012), which presumably lack mesonephric duct-derived tubular or glandular accessory tissue, although phenotypes remain poorly defined with respect to internal genitalia.…”

Section: Discussionmentioning

confidence: 99%

Equine 5α-reductase activity and expression in epididymis

Corbin

Legacki

Ball

et al. 2016

Journal of Endocrinology

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The 5α-reductase enzymes play an important role during male sexual differentiation, and in pregnant females, especially equine species where maintenance relies on 5α-reduced progesterone, 5α-dihydroprogesterone (DHP). Epididymis expresses 5α-reductases but was not studied elaborately in horses. Epididymis from younger and older postpubertal stallions was divided into caput, corpus and cauda and examined for 5α-reductase activity and expression of type 1 and 2 isoforms by quantitative realtime polymerase chain reaction (qPCR). Metabolism of progesterone and testosterone to DHP and dihydrotestosterone (DHT), respectively, by epididymal microsomal protein was examined by thin-layer chromatography and verified by liquid chromatography tandem mass spectrometry (LC-MS/MS). Relative inhibitory potencies of finasteride and dutasteride toward equine 5α-reductase activity were investigated. Pregnenolone was investigated as an additional potential substrate for 5α-reductase, suggested previously from in vivo studies in mares but never directly examined. No regional gradient of 5α-reductase expression was observed by either enzyme activity or transcript analysis. Results of PCR experiments suggested that type 1 isoform predominates in equine epididymis. Primers for the type 2 isoform were unable to amplify product from any samples examined. Progesterone and testosterone were readily reduced to DHP and DHT, and activity was effectively inhibited by both inhibitors. Using epididymis as an enzyme source, no experimental evidence was obtained supporting the notion that pregnenolone could be directly metabolized by equine 5α-reductases as has been suggested by previous investigators speculating on alternative metabolic pathways leading to DHP synthesis in placenta during equine pregnancies.

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Section: Discussionmentioning

confidence: 99%

Equine 5α-reductase activity and expression in epididymis

Corbin

Legacki

Ball

et al. 2016

Journal of Endocrinology

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“…Where testing was possible, all reported cases have been SRY -negative by Southern blotting, PCR, RFLP, or FISH ( fig. 2 B) [Milliken et al, 1995;Pailhoux et al, 1995;Meyers-Wallen et al, 1997;Abe et al, 1999;Buoen et al, 2000;Vaughan et al, 2001;Bannasch et al, 2007;Jaszczak, 2010;Villagómez et al, 2011]. Some horses may display male behaviors including filly herding, teasing, biting, and mounting due to increased levels of testosterone from testicular tissue.…”

Section: Dsd In Horsementioning

confidence: 99%

“…[ Bannasch et al, 2007] [ Raudsepp et al, 2010] [ McGee, 2011] [ Bowling et al, 1987] Arabian Andalusian Quarter Horse Appaloosa Arabian [Miyake et al, 1979;Halnan, 1985;Bowling et al, 1987;Paget et al, 2001] [ Buoen et al, 2000;Villagomez et al, 2011] [ Raudsepp et al, 2010;Villagomez et al, 2011] [ Raudsepp et al, 2010] [ Kent et al, 1986;Bowling et al, 1987;Kent et al, 1988] Half-bred Anglo-Arabian Appaloosa Standardbred Mixed Warmblood Morgan [Bugno et al, 2007] [ Buoen et al, 2000] [ Pailhoux et al, 1995;Mäkinen et al, 1999;Makinen et al, 2001;Raudsepp et al, 2010;Villagomez et al, 2011] [ Raudsepp et al, 2010] [ Bowling et al, 1987] Half-Arabian Arabian Thoroughbred Oldenburg Pasa Fino [Gill et al, 1988] [ Buoen et al, 2000;Villagomez et al, 2011] [ Abe et al, 1999;Bugno et al, 2003;Raudsepp et al, 2010;Villagomez et al, 2011] [ Kuiper et al, 2010] [ Kent et al, 1986;Kent et al, 1988] Clydesdale Belgian Quarter Horse Quarter Horse [Klunder et al, 1990] [ Villagomez et al, 2011] [ Raudsepp et al, 2010;Villagomez et al, 2011] [ Kent et al, 1986;Bowling et al, 1987;Kent et al, 1988] Fjord Konik Polski Sta...…”

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confidence: 99%

Disorders of Sexual Development in the Domestic Horse, <i>Equus caballus</i>

Lear

McGee²

2011

Sex Dev

Self Cite

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Abnormalities of sexual development causing infertility in horses have been investigated since the early 1970's. Conventional cytogenetic analysis by karyotyping has been the primary tool used to investigate these horses. Abnormalities have a broad range, from a phenotypically normal mare with gonadal dysgenesis to a horse with ambiguous external genitalia and internal male and female organs. Cytogenetic analysis can determine genetic sex but cannot identify mutations or deletions of genes involved in the sex determination pathway. Molecular technologies have been developed to confirm cytogenetic results and to aid in identifying the genetic causes of abnormal sex determination in horses. In this paper, we review the historical development of methods used to understand abnormal sexual development in the horse as well as summarize cases reported over the last 40-50 years.

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“…In 4 cases, mares with this condition exhibited hypoplastic testes [Villagómez et al, 2011], and in 1 case, the gonads were not analysed, however, it was suggested that the mare was affected with an androgen insensitivity syndrome [Switonski et al, 2005]. Thus, an alteration in the function of primary testis-determining genes does not appear to be the cause of these anomalies.…”

Section: Xy Sex Reversal In the Horsementioning

confidence: 99%

Natural Exceptions to Normal Gonad Development in Mammals

Jiménez

Barrionuevo²,

Burgos³

2012

Sex Dev

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Gonads are the only organs with 2 possible developmental pathways, testis or ovary. A consequence of this unique feature is that mutations in genes controlling gonad development give rise not only to gonadal malformation or dysfunction but also to frequent cases of sex reversal, including XY females, XX males and intersexes. Most of our current knowledge on mammalian sex determination, the genetic process by which the gonadal primordia are committed to differentiate as either testes or ovaries, has derived mainly from the study of sex-reversed mice obtained by direct genetic manipulation. However, there are also numerous cases of natural exceptions to normal gonad development which have been described in a variety of mammals, including both domestic and wild species. Here, we review the most relevant cases of: (1) natural, non-induced sex reversal and intersexuality described in laboratory rodents, including Sxr and B6-Y^DOM mice; (2) sex reversal in domestic animals, including freemartinism in bovids and pigs, XX sex reversal in pigs, goats and dogs, XY sex reversal in the horse, and sex chromosome chimerism and sex reversal in the cat, and (3) sex reversal in wild mammals, including the generalised true hermaphroditism described in talpid moles, XY sex reversal in Akodon, Microtus and Dicrostonyx species, males lacking a Y chromosome and SRY in Ellobius lutescens, the X* chromosome of Myopus schisticolor, and sex chromosome mosaicism and X0 females in Microtus oregoni. These studies are necessary to elucidate particular aspects of mammalian gonad development in some instances and to understand how the genetic mechanisms controlling gonad development have evolved.

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Equine Disorders of Sexual Development in 17 Mares Including XX, <i>SRY</i>-Negative, XY, <i>SRY</i>-Negative and XY, <i>SRY</i>-Positive Genotypes

Cited by 44 publications

References 105 publications

Equine 5α-reductase activity and expression in epididymis

Equine 5α-reductase activity and expression in epididymis

Disorders of Sexual Development in the Domestic Horse, <i>Equus caballus</i>

Natural Exceptions to Normal Gonad Development in Mammals

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