No full-text available
To read the full-text of this research,
you can request a copy directly from the author.
Androgen insensitivity syndrome in a Thoroughbred mare (64, XY - Testicular feminization)
Abstract
A Thoroughbred mare was presented for stallion-like behavior. Reproductive and ultrasonographic evaluation, testosterone assays, and karyotyping confirmed a diagnosis of androgen insensitivity syndrome (64, XY--testicular feminization). Surgery to remove abdominal testicles was successful in alleviating the behavioral abnormality. This condition is discussed with reference to the current literature.
... Another less frequently observed phenotype shows various degrees of masculinization and virilization (Kent et al. 1986;Long 1988;Lear & Bailey 2008;Villagomez et al. 2009). The ÔmasculineÕ-type XY mares usually have abnormally developed genital tract, and the gonads can range from ovotestes to testicular feminization (Kent et al. 1986;Bowling et al. 1987;Kent et al. 1988a;Howden 2004;Villagomez et al. 2009), leading to male pseudohermaphrodites. All XY female horses studied so far have been found to be infertile, except one that gave birth to a normal 64,XX filly (Sharp et al. 1980). ...
... These mares display features that are not typically observed in SRYnegative animals, such as stallion-like behaviour, large body size, abnormal external genitalia, elevated blood testosterone levels, and male rather than female gonadal dysgenesis (Table 1). Based on this, it is possible that many more SRY-positive XY females have been described earlier, but because of the lack of molecular tools, they were not properly identified (Kieffer 1976;Kent et al. 1986Kent et al. , 1988aCrabbe et al. 1992;Howden 2004). Therefore, the Ômascu-lineÕ-type equine XY sex reversal might be more prevalent than the single previous report (Switonski et al. 2005) and the 5 cases described in this study. ...
... However, human studies suggest that a Y-linked ÔgrowthÕ gene might be responsible for the larger than usual body size (adult height) (Ogata & Matsuo 1992;McDonough 2003) of XY females. Further, it has been proposed that testicular feminization and male pseudohermaphroditism in SRY-positive mares might be caused by a mutation in the X-linked androgen receptor (AR) gene (Crabbe et al. 1992;Howden 2004;Switonski et al. 2005). To date, there is no experimental evidence to support this. ...
Male-to-female 64,XY sex reversal is a frequently reported chromosome abnormality in horses. Despite this, the molecular causes of the condition are as yet poorly understood. This is partially because only limited molecular information is available for the horse Y chromosome (ECAY). Here, we used the recently developed ECAY map and carried out the first comprehensive study of the Y chromosome in XY mares (n=18). The integrity of the ECAY in XY females was studied by FISH and PCR using markers evenly distributed along the euchromatic region. The results showed that the XY sex reversal condition in horses has two molecularly distinct forms: (i) a Y-linked form that is characterized by Y chromosome deletions and (ii) a non-Y-linked form where the Y chromosome of affected females is molecularly the same as in normal males. Further analysis of the Y-linked form (13 cases) showed that the condition is molecularly heterogeneous: the smallest deletions spanned about 21 kb, while the largest involved the entire euchromatic region. Regardless of the size, all deletions included the SRY gene. We show that the deletions were likely caused by inter-chromatid recombination events between repeated sequences in ECAY. Further, we hypothesize that the occurrence of SRY-negative XY females in some species (horse, human) but not in others (pig, dog) is because of differences in the organization of the Y chromosome. Finally, in contrast to the Y-linked SRY-negative form of equine XY sex reversal, the molecular causes of SRY-positive XY mares (5 cases) remain as yet undefined.
... Em seguida, é determinado o sexo gonadal, no qual o gene SRY (sex determining region Y), localizado no cromossomo Y, é responsável pela masculinização do organismo em desenvolvimento através da diferenciação gonadal em testículos. Se o indivíduo é do sexo genético XX e não possui o gene SRY, a gônada se diferencia em ovário [17]. O sexo fenotípico se desenvolve de forma ativa no macho, devido ao estímulo gerado pela testosterona. ...
... Do ponto de vista hormonal, frequentemente os hermafroditas apresentam valores de testosterona normais, compatível com a presença de células de Leydig, e hormônio anti-mulleriano detectável, compatível com células de Sertoli funcionais [17]. Para a avaliação da integridade da via sintética de testosterona utilizou-se hCG na dose de 10000UI por via endovenosa, dosando-se os hormônios da via sintética de testosterona, antes e 2 h após o estímulo [20]. ...
Background: Intersexuality is considered an alteration in the animal development that opposes the characteristics determined by the genetic sex, resulting in an individual with characteristic features of both sexes. The objective of this work is to report a case of male pseudohermaphroditism of a Criollo breed horse referred to the Hospital de Clínicas Veterinárias (HCV) of the Universidade Federal de Pelotas, RS, Brazil. We gather information on the intersexuality diagnostics highlighting cytogenetics as an additional tool to diagnosis.Case: A Criollo breed horse was attended at the HCV with the main complaint of morphological anomaly of the external genitalia. The animal presented female external features, characterized by mammal glands and female genitalia. The horse also showed a rudimentary penis-like structure, caudally oriented shrouded by a cutaneous crease similar to a vulva and presented male behavior. The external genitalia was examined but the vaginoscope could not be inserted since the crease ended in a sac, with no openings. Rectal palpation and transrectal ultrasound could not reveal the presence of female gonads. Urethral ultrasound revealed the pelvic urethra and the openings of the male accessory glands. The equine was subjected to hormonal challenge with human chorionic gonadotropin (hCG). First sample presented a testosterone concentration of 20 ng/dL; second sample, on the other hand, presented a testosterone concentration of 60 ng/dL after the stimulus. The Polimerase Chain Reaction technique revealed absence of gene SRY (sex determiningregion Y). The cytogenetic study was conducted with the lymphocytes obtained from peripherical venous blood. From this, we could verify that the patient was genetically male with karyotype 64 XY. Necropsy showed presence of prepuce and rudimentary penis at the anatomical site of the vulva without scrotum. In the pelvic cavity, a structure similar to a uterine body was observed, with the horns ending at the ovaries anatomical sites, where a structure similar to testicles was found with underdeveloped seminiferous tubules lacking production of spermatozoa and rudimentary epididymis with epididymal ducts coated with primitive stereocilia.Discussion: True hermaphroditism is defined by the presence of ovarian and testicular tissues in the same individual, as separate gonads or combined, as ovotestis. On the other hand, the pseudo-hermaphrodite is an individual with only one gonad, and external genitalia and secondary characteristics of the opposite sex. Urethral endoscopy allowed the visualization of the pelvic urethra and the male sexual glands openings. Following stimulation with hCG, testosterone level increased in 40 ng/dL, evidencing the presence of testicular tissue. Sexual differentiation is determined by the presence or absence of the Y chromosome and by the expression of gene SRY. The animal studied here had karyotype 64 XY and lacked gene SRY, characterizing a condition where testicular differentiation occurred in the absence of gene SRY. It is possible to conclude that clinical evaluation, complementary exams and hormonal analysis allowed the identification of intersexuality. However, only molecular, cytogenetic and histological analyses allowed the definitive diagnosis of male pseudohermaphrodite.
... Em seguida, é determinado o sexo gonadal, no qual o gene SRY (sex determiningregion Y), localizado no cromossomo Y, é responsável pela masculinização do organismo em desenvolvimento através da diferenciação gonadal em testículos. Se o indivíduo é do sexo genético XX e não possui o gene SRY, a gônada se diferencia em ovário [17]. O sexo fenotípico se desenvolve de forma ativa no macho, devido ao estímulo gerado pela testosterona. ...
... Do ponto de vista hormonal, frequentemente os hermafroditas apresentam valores de testosterona normais, compatível com a presença de células de Leydig, e hormônio anti-mulleriano detectável, compatível com células de Sertoli funcionais [17]. Para a avaliação da integridade da via sintética de testosterona utilizou-se hCG na dose de 10000UI por via endovenosa, dosando-se os hormônios da via sintética de testosterona, antes e 2 h após o estímulo [20]. ...
Background: Intersexuality is considered an alteration in the animal development that opposes the characteristics determined by the genetic sex, resulting in an individual with characteristic features of both sexes. The objective of this work is to report a case of male pseudohermaphroditism of a Criollo breed horse referred to the Hospital de Clínicas Veterinárias (HCV) of the Universidade Federal de Pelotas, RS, Brazil. We gather information on the intersexuality diagnostics highlighting cytogenetics as an additional tool to diagnosis. Case: A Criollo breed horse was attended at the HCV with the main complaint of morphological anomaly of the external genitalia. The animal presented female external features, characterized by mammal glands and female genitalia. The horse also showed a rudimentary penis-like structure, caudally oriented shrouded by a cutaneous crease similar to a vulva and presented male behavior. The external genitalia was examined but the vaginoscope could not be inserted since the crease ended in a sac, with no openings. Rectal palpation and transrectal ultrasound could not reveal the presence of female gonads. Urethral ultrasound revealed the pelvic urethra and the openings of the male accessory glands. The equine was subjected to hormonal challenge with human chorionic gonadotropin (hCG). First sample presented a testosterone concentration of 20 ng/dL; second sample, on the other hand, presented a testosterone concentration of 60 ng/dL after the stimulus. The Polimerase Chain Reaction technique revealed absence of gene SRY (sex determiningregion Y). The cytogenetic study was conducted with the lymphocytes obtained from peripherical venous blood. From this, we could verify that the patient was genetically male with karyotype 64 XY. Necropsy showed presence of prepuce and rudimentary penis at the anatomical site of the vulva without scrotum. In the pelvic cavity, a structure similar to a uterine body was observed, with the horns ending at the ovaries anatomical sites, where a structure similar to testicles was found with underdeveloped seminiferous tubules lacking production of spermatozoa and rudimentary epididymis with epididymal ducts coated with primitive stereocilia. Discussion: True hermaphroditism is defined by the presence of ovarian and testicular tissues in the same individual, as separate gonads or combined, as ovotestis. On the other hand, the pseudo-hermaphrodite is an individual with only one gonad, and external genitalia and secondary characteristics of the opposite sex. Urethral endoscopy allowed the visualization of the pelvic urethra and the male sexual glands openings. Following stimulation with hCG, testosterone level increased in 40 ng/dL, evidencing the presence of testicular tissue. Sexual differentiation is determined by the presence or absence of the Y chromosome and by the expression of gene SRY. The animal studied here had karyotype 64 XY and lacked gene SRY, characterizing a condition where testicular differentiation occurred in the absence of gene SRY. It is possible to conclude that clinical evaluation, complementary exams and hormonal analysis allowed the identification of intersexuality. However , only molecular, cytogenetic and histological analyses allowed the definitive diagnosis of male pseudohermaphrodite.
... Horses affected by an AR-like syndrome have female external genitalia, high plasma testosterone concentrations and exhibit stallion-like behaviour and infertility. They have a 64,XY karyotype and SRY and ZFY genes are present (Howden, 2004;Switonski et al., 2005). ...
... The length of a CAG repeat in exon 1 of the AR gene is associated with infertility in men (Shah et al., 2003). In horses, some cases of AIS are thought to be associated with mutations in AR (Crabbe et al., 1992;Pailhoux et al., 1995;Howden, 2004;Switonski et al., 2005). ...
Stallion fertility is of high economic importance for the horse industry. The discovery of molecular mechanisms affecting fertility will be facilitated by the horse genome assembly and the development of novel tools for analysing complex genetic traits. Genetic markers in candidate genes, such as CRISP3, SPATA1 and INHBA, in breeding stallions have been associated with pregnancy rate per oestrus in mares. This paper reviews candidate autosomal, X and Y genes for stallion fertility, including genes encoding hormones and their receptors of the hypothalamic-pituitary axis, proteins of the seminal plasma, proteins involved in spermatozoa–ovum binding and genes influencing sexual development, as well as Y-specific genes. Their chromosomal location and gene structure are described, based on the horse genome assembly EquCab2.0 and a resource for markers located within or in close vicinity to the candidate genes (including pre-designed primer sequences). The application of genetic markers in improving stallion fertility for breeding and management is discussed.
... From a hormonal point of view, hermaphrodites often have normal testosterone values, compatible with the presence of Leydig cells and detectable anti-Mullerian hormone, compatible with functional Sertoli cells [7] . On the other hand, in cases of pseudo hermaphroditism, testosterone levels are variable. ...
A 4-year-old Straight Egyptian Arabian horse was evaluated in 2016 due to a malformation of external genitalia and male sexual behavior. On physical examination, small teats in the inguinal area and a rudimentary penis-like structure surrounded by a clitoral fossa could be seen. There was no evidence of vulva and vaginal canal. A stallion like behavior was observed, especially in the presence of mares in heat, when the animal was excited and aggressive and had erection of the penis-like structure. Blood samples were collected for two purposes: hormonal (testosterone and estradiol plasma concentration analyses) and genetic (cytogenetic and molecular analysis). The karyotype showed 32 pairs of chromosomes in all cells (2n = 64) including 14 and 18 pairs of metacentric and acrocentric chromosomes respectively, in agreement with a presumptive 64, XX complement. This result agree with STR and SNP molecular analysis, which also ruled out the possibility of hematopoietic chimerism. In addition, SNP genotyping showed no numerical chromosomal aberrations or large deletions or duplications, that can be linked to the phenotype in any autosome, nor numerical chromosomal abnormalities in the father and mother of the horse analyzed. In conclusion, we determined that the animal in the present study is a male pseudo-hermaphrodite.
... This group of XY DSDs encompasses female-like horses showing various degrees of masculinization and virilization, as well as stallion-like behavior. These horses usually have abnormally developed genital tract, the gonads can range from ovotestes to testicular feminization, and the cases are described as male pseudohermaphrodites, intersex or ambiguous sex [28,44,133,134,136,137,[145][146][147][148][149]. ...
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.
... Many forms of DSDs manifest as discrepancies between the genetic sex (sex chromosomes), gonadal sex (testes or ovaries) and phenotypic sex. In literature, the resulting phenotypes appear under terms like intersexuality, gonadal dysgenesis, pseudohermaphroditism, testicular feminization, true hermaphroditism, and sex reversal syndromes (Howden 2004;Villagomez et al, 2011;Lear and McGee 2012), depending on at which levels (genetic, gonadal, phenotypic) sexual characteristics are altered or observed. ...
enomic and epigenomic factors play important role in the causation of human disease. With the advent of improved
molecular biology techniques, the genomic and epigenomic basis for increasing number of diseases is coming up.
This is also true with male infertility. Genetic factors (chromosomal, Yq microdeletion and cystic fibrosis) are
responsible for approximately 30% of cases of male infertility. About 40% of cases of male infertility are currently
categorized as idiopathic and may be linked to unknown genetic/genomic or epigenomic abnormalities. Here, we summarize
our current work with genomic and epigenomic approaches on testicular germ cell disorders, one of the common causes of
male infertility.
Testicular germ cell disorder (other than neoplasm) refers to conditions where testes fail to produce spermatozoa due to
interruption of germ cell development and differentiation presence of germ cells (few or normal numbers) but differentiation
into spermatozoa/sperm is interrupted. This may be classified into two distinct subtypes viz., Pre-meiotic Arrest of Germ
Cell Differentiation (Early Maturation Arrest) and Post-meiotic Arrest of Germ Cell Differentiation (Late Maturation
Arrest).
All human studies till now were restricted to clinical, endocrine & base line genetic (chromosomes & Yq microdeletion)
parameters only. Etiologic factors were identifiable in ~50% cases and remaining 50% are still unknown. Here, we have
carried out prospective study at genomic and epigenomic level to find out underlying genomic and epigenomic factors in
idiopathic Testicular Germ Cell Disorders/arrest.
This study is based on 70 cases of apparent idiopathic testicular germ cell differentiation disorder (maturation arrest) cases.
Known causes viz., mumps orchitis, varicocele, torsion, trauma, cryptorchidism, etc or treatment with chemotherapeutic
drugs was excluded before inclusion into the study. FISH with XY probes were carried out in addition to conventional
chromosome analysis to find out sex chromosome aneuploidy. STS PCR analysis was carried out for Yq microdeletion
studies. Serum heavy metals were also estimated in serum in 31 cases. Later, in a subset of 68 idiopathic testicular germ cell
disorder cases and 10 controls DNA microarray was carried out to find out any association with recurrent CNV/LOH. Global
methylation status was evaluated by using methylated DNA ELISA in all cases. Finally, 12 idiopathic testicular germ cell
disorder cases (5 early and 7 late idiopathic maturation arrest cases) were subjected for epigenome analysis using Illumina
450K epigenomic microarray.
DNA microarray finding on idiopathic testicular germ cell differentiation /MA cases showed recurrent CNVs on sex
chromosomes (both X & Y chromosomes). The recurrent CNVs are Yp11.31-p11.2 (17 cases with 3 copies), Yp11.2 (9
cases with 3 copies), Yq11.223 (7 cases with deletion), Yq11.23 (4 cases with deletion), Yq11.223-11.233 (3 cases with 3
copies), Xp11.23 (7 cases with 2 copies), Xq28 (5 cases with 3 copies), 14q32.33 (5 cases with 3 copies), 14q11.2 (3 cases
with 3 copies), 7q11.1-11.21 (2 cases with 3 copies), 10q11.22 (2 cases with 3 copies), 16p11.2 (2 cases with 3 copies),
17p11.22 (2 cases with 3 copies) and 22q11.22 (2 cases with 3 copies).
CNV in sex chromosomes PAR 1, 2 & 3 were also frequent (Y PAR1 in 3 cases & X PAR 1 in 8 cases; Y PAR2 in none &
X PAR 2 in 11 cases; Y PAR3 in 12 cases & X PAR 3 in 4 cases) and that affects pairing thus meiotic arrest/spermatogenic
arrest and male infertility. Methylation DNA ELISA for global methylation shows global hypomethylation in 5 cases (MA
27, 44, 51, 70, 77). Global methylation between two groups was also comparable (p value of 0.735 vs. 0.732). Similarly,
epigenomic array detected hypomethylation in GSTT1 gene and Hypermethylation in ACAP3 gene. Role of associated genes
within CNVs (including PAR 1, 2 & 3) and CPG islands in probable causation of maturation arrest will be discussed in
presentation.
G
... The DSD terminology has also been adopted for use in animals, with published cases in domestic animals being reviewed by Villagómez et al. [2009]. While male pseudohermaphroditism or AIS has been reported in several domestic species including dogs, cats, horses, and cattle [Howden, 2004;Lyle, 2007], detailed molecular investigations in horses are restricted to 2 studies. A missense mutation (c.2042G>C) was identified in members of a Thoroughbred family and presumed to result in the substitution of a very important tryptophan residue with serine in the AR LBD [Bolzon et al., 2016], and a rare start codon mutation (c.1A>G) in the American Quarter horse breed resulted in complete androgen insensitivity for 3 members of the horse family [Révay et al., 2012]. ...
Testicular feminization, an earlier term coined for describing a syndrome resulting from failure of masculinization of target organs by androgen secretions during embryo development, has been well documented not only in humans but also in the domestic horse. The pathology, actually referred to as androgen insensitivity syndrome (AIS), has been proposed to follow an X-linked recessive pattern of inheritance in some horse breeds already investigated. Affected individuals are characterized by a female phenotype but with a stallion genotype of 64,XY SRY+ constitution. We identified a Warmblood horse pedigree segregating AIS, where the molecular analyses of the androgen receptor gene in the family provided evidences that a 25-bp deletion of the DNA-binding domain is causative of this equine syndrome.
... Intersexuality has been reported in a wide array of domestic animal species including dogs, buffalo, and horses [Howden, 2004;Iannuzzi et al., 2004;Villagómez et al., 2009a;Poth et al., 2010]. The first molecular link between a 64,XY DSD condition and the AR was documented by Révay et al. [2012], who identified a start codon mutation in the AR gene of an American Quarter Horse pedigree that resulted in complete androgen insensitivity for 3 members of the horse family. ...
Disorders of sex development (DSD) have long been documented in domestic animal species including horses. However, there is only a single report of an androgen receptor (AR) mutation causative of such a DSD syndrome in a horse pedigree. Here, we present a new familial AR mutation in horses. A missense mutation (c.2042G>C) at AR exon 4 explains the segregation of the DSD in a Thoroughbred horse pedigree. The mutation, expected to affect the ligand-binding domain of the AR protein, led to complete androgen insensitivity of 64,XY SRY+, testicular DSD individuals. Additionally, the design of a PCR-RFLP technique provided an accurate molecular test for the identification of horses carrying the mutation.
... A disposi??o natural ? que qualquer feto desenvolva uma genit?lia externa e conforma??o corporal feminina na aus?ncia dos efeitos masculinizantes dos andr?genos (Howden, 2004Camacho et al., 2007). A estimativa do coeficiente de inclina??o da reta prediz que, para um grama de ganho de peso de ovinos da ra?a Santa In?s do sexo feminino, os ovinos do sexo masculino ganham em m?dia 1,36 gramas, ou seja, 0,36 gramas a mais do nascimento ao desmame e no p?s-desmame. ...
The purpose was to evaluate the reproductive performance of woolless ewes due to the feeding management of offsprings and weaning age in addition to measuring the effect of gender on weight gain of lambs. Sixty-four Santa Ines crossbred ewes were distributed in a completely randomized design in a factorial 4 x 2 x 2 - four weaning ages (56, 70, 84 and 98 days), sex and feeding management of the offspring, each treatment with four replications. The ewes were managed with the offsprings at the foot in 14 paddocks of 1,5 or 2,0 hectares, formed with Brachiaria humid cola. The offsprings were born by single birth, of Santa Ines pure of origin (PO). After the weaning of all groups, sixty-four lambs (32 males and 32 females) were randomly assigned in individual stalls and confined for 30 days. The comparison of the parameters was carried out by the adjustment of the simple linear regression model. It was verified over time addiction of the offspring feed management of + 3,7% (P<0,05) for the calving intervals and of + 1,4% (P<0,05) for the service period. There was increasing linear effect (P<0,05) of weaning age on calving intervals and service period. It was verified over time, addiction of the offspring sex of + 2,0% (P<0,05) for the calving intervals and + 0,8% (P<0,05) for the ewes service period. It was observed over time addiction of sex of + 35,2% and + 36,9% (P<0,05), respectively, for the daily weight gain of lambs from birth to weaning and post-weaning in feedlot. The supplementation of the offspring in private feeder and the anticipation of the weaning age reduce the calving intervals and the service period of woolless ewes in Brachiaria humidicula pasture. The offspring sex is the source of variation in the analysis of reproductive efficiency of ewe's matrices and in the weight gain of Santa Ines crossbred lambs from birth to weaning, and after weaning.
... Tabela 5. Período de serviço (dias) de ovelhas mestiças da raça Santa Inês manejadas em Brachiaria humidícula, de acordo com idade de desmame e sexo de crias suplementadas com alimento concentrado em alimentador privativo (Howden, 2004). O sexo fenotípico se desenvolve de forma ativa no macho, estimulado pela testosterona produzida pelas gônadas diferenciadas (Nascimento e Santos, 2003). ...
Objetivou-se avaliar o desempenho reprodutivo de ovelhas deslanadas em função do manejo alimentar das crias e idade de desmame, além de mensurar o efeito do sexo no ganho de peso de cordeiros. Sessenta e quatro ovelhas mestiças da raça Santa Inês foram distribuídas em delineamento inteiramente ao acaso, em esquema fatorial 4 x 2 x 2 - quatro idades de desmame (56, 70, 84 e 98 dias), sexo e manejo alimentar das crias, cada tratamento com quatro repetições. As ovelhas foram manejadas com a cria ao pé, em 14 piquetes de 1,5 ou 2,0 hectares, formados com pastagem de Brachiaria humidícola. As crias nascidas de partos simples, filhos de reprodutores Santa Inês puros de origem (PO). Após o desmame de todos os grupos, sessenta e quatro cordeiros (32 machos e 32 fêmeas) foram distribuídos ao acaso em baias individuais e confinados por 30 dias. A comparação dos parâmetros foi realizada pelo ajuste do modelo de regressão linear simples. Verificou-se vício de tempo longo do manejo alimentar das crias de + 3,7% (P<0,05) para o intervalo entre partos e de + 1,4% (P<0,05) para o período de serviço. Houve efeito linear crescente (P<0,05) da idade de desmame sobre o intervalo entre partos e período de serviço. Verificou-se vício de tempo longo do sexo das crias de + 2,0% (P<0,05) para o intervalo entre partos e de + 0,8% (P<0,05) para o período de serviço das ovelhas. Constatou-se vício de tempo longo do sexo de + 35,2% e + 36,9% (P<0,05), respectivamente, para o ganho de peso diário de cordeiros do nascimento ao desmame e pós desmame em confinamento. A suplementação das crias em alimentador privativo e a antecipação da idade de desmame reduzem o intervalo entre partos e período de serviço de ovelhas deslanadas em pastagem de Brachiaria humidícula. O sexo da cria é fonte de variação na análise da eficiência reprodutiva de matrizes ovinas e no ganho de peso de cordeiros mestiços da raça Santa Inês do nascimento ao desmame e após o desmame.
... Thorough characterization of domestic animal cases can be hindered by lack of awareness of the syndrome and the limited availability of laboratory technology. Kieffer et al. [1976], Kent et al. [1988], Crabbe et al. [1992] and Howden [2004] postulated AIS in representative cases of horse testicular feminization without molecular genetic testing. Investigation of the SRY gene was used to discriminate potential AIS cases from 64,XY SRY -negative mares, which can arise through deletions of the major sex-determining gene on the Y chromosome [Switonski et al., 2005;Raudsepp et al., 2010;Knobbe et al., 2011]. ...
Genetic sex in mammals is determined by the sex chromosomal composition of the zygote. The X and Y chromosomes are responsible for numerous factors that must work in close concert for the proper development of a healthy sexual phenotype. The role of androgens in case of XY chromosomal constitution is crucial for normal male sex differentiation. The intracellular androgenic action is mediated by the androgen receptor (AR), and its impaired function leads to a myriad of syndromes with severe clinical consequences, most notably androgen insensitivity syndrome and prostate cancer. In this paper, we investigated the possibility that an alteration of the equine AR gene explains a recently described familial XY, SRY + disorder of sex development. We uncovered a transition in the first nucleotide of the AR start codon (c.1A>G). To our knowledge, this represents the first causative AR mutation described in domestic animals. It is also a rarely observed mutation in eukaryotes and is unique among the >750 entries of the human androgen receptor mutation database. In addition, we found another quiet missense mutation in exon 1 (c.322C>T). Transcription of AR was confirmed by RT-PCR amplification of several exons. Translation of the full-length AR protein from the initiating GTG start codon was confirmed by Western blot using N- and C-terminal-specific antibodies. Two smaller peptides (25 and 14 amino acids long) were identified from the middle of exon 1 and across exons 5 and 6 by mass spectrometry. Based upon our experimental data and the supporting literature, it appears that the AR is expressed as a full-length protein and in a functional form, and the observed phenotype is the result of reduced AR protein expression levels.
... AIS has a wide spectrum of severity with the most severe patients having totally inactive AR, manifesting as complete AIS (CAIS), which features a female phenotype with normal somatic and external genital features (but no female internal genitalia), despite a 46XY karyotype and undescended inguinal testes (Oakes et al., 2008). These features, once known as testicular feminization (tfm) for its conjunction of female external with male internal genitalia, were described in humans over 50 years ago (Morris, 1953) with similar findings subsequently reported in numerous mammalian species examined (Quigley et al., 1995;rodent: Bardin et al., 1970;Lyon and Hawkes, 1970;Allison et al., 1971;Olsen, 1979;Tsuji and Matsumoto, 1982;Mullen and Hawe, 1979;dog: Fentener van Vlissingen et al., 1988;Peter et al., 1993a;Wernham and Jerram, 2006;Nowacka-Woszuk et al., 2007;cat: Meyers-Wallen et al., 1989;Lawhorn, 1989;Bredal et al., 1997;cattle: Long and David, 1981;Peter et al., 1993b;mare: Kieffer, 1976;Crabbe et al., 1992;Howden, 2004;Switonski et al., 2005;deer: Scanlon et al., 1975;pig: Lojda and Navratil, 1969;monkey: Pasello-Legrand and Mowat, 2004) as well as in several distinct mouse tfm mutations (Politch et al., 1988;Tanaka et al., 1994). Human AR mutations comprise a complete spectrum of effects, covering the range of male intersex development of external genitalia from minimally virilized females to mild under-virilization with nearnormal male genital development (hypospadias being the most sensitive indicator), or even a normal male phenotype with only infertility due to non-functional but morphologically normal sperm (Quigley et al., 1995). ...
Androgens and the androgen receptor (AR) have well known roles in male reproduction, and recent genetic mouse models inactivating the Ar gene have conclusively defined a role for androgens in female reproduction. In males, AR gene inactivation severely disrupts spermatogenesis by interrupting completion of meiosis, thereby eliminating production of mature sperm leading to male sterility. These effects have overshadowed the study of additional post-meiotic androgen effects required for the production of fully functional spermatozoa, as well as the production of females with complete androgen insensitivity which cannot be produced by natural breeding. However, these limitations have been overcome by the creation of global and cell-specific AR knockout (ARKO) mouse models using Cre-LoxP genetic engineering.
Pubmed searches were carried out using the following search terms: androgen receptor, knockout mouse and fertility. Articles published before the end of November 2009 were included.
These experimental models have identified cell-specific AR-mediated androgen actions in testis and androgen actions in sex accessory glands independent of testicular effects which are crucial for sperm maturation, motion and fertilizing ability. The ability to produce homozygous ARKO females has revealed that AR-mediated androgen actions are important for normal female fertility. AR function is required for full functionality in follicle health, development and ovulation through both intra-ovarian and neuroendocrine mechanisms.
ARKO mouse models provide valuable tools to unravel novel roles of AR-mediated actions in male and female reproductive function, and new insights into the role of androgens in human reproductive function.
... Clinical examination of both horses revealed similar pictures: normal external genitalia, no uterus, hypoplastic testes and masculine behaviour. The latest report on the androgen insensitivity syndrome in the horse was presented by Howden (2004). The intersexual animal, presenting stallion-like behaviour, had XY chromosome complement and increased concentration of testosterone. ...
A 5-year-old Thoroughbred mare was subjected to cytogenetic and molecular analysis because of infertility and masculine behaviour. Chromosome studies, including painting with the whole X chromosome specific probe, revealed a male chromosome complement (64,XY). The PCR amplification of the SRY and ZFY genes showed the presence of both those genes, while the endocrinological study demonstrated a high level of testosterone (9.7 nmol/l). Sequencing of the SRY gene (1121 bp), comprising also 5'- and 3'-UTRs, did not reveal any differences when compared with the sequence of normal stallions. It was proposed that this mare represents the androgen insensitivity syndrome (testicular feminization syndrome).
A 4-year-old Straight Egyptian Arabian horse was evaluated in 2016 due to a malformation of external genitalia and male sexual behavior. On physical examination, small teats in the inguinal area and a rudimentary penis-like structure surrounded by a clitoral fossa could be seen. There was no evidence of vulva and vaginal canal. A stallion like behavior was observed, especially in the presence of mares in heat, when the animal was excited and aggressive and had erection of the penis-like structure. Blood samples were collected for two purposes: hormonal (testosterone and estradiol plasma concentration analyses) and genetic (cytogenetic and molecular analysis). The karyotype showed 32 pairs of chromosomes in all cells (2n=64) including 14 and 18 pairs of metacentric and acrocentric chromosomes respectively, in agreement with a presumptive 64, XX complement. This result agree with STR and SNP molecular analysis, which also ruled out the possibility of hematopoietic chimerism. In addition, SNP genotyping showed no numerical chromosomal aberrations or large deletions or duplications, that can be linked to the phenotype in any autosome, nor numerical chromosomal abnormalities in the father and mother of the horse analyzed. In conclusion, we determined that the animal in the present study is a male pseudohermaphrodite.
Intersexuality is a rare congenital anomaly of horses. Diagnosis of intersexuality is difficult because there are usually no specific changes in the reproductive tract visible. During a period of five years, ten patients with reduced fertility or suspected intersexuality respectively were investigated using cytogenetic, molecular genetic, histopathological and endocrinological methods. In one case a 64,XX/63,X0 mosaicism was found. In six cases male pseudohermaphroditism was verified. These patients showed a male karyotype, testes and rudimentary parts of a female reproductive tract were present. One horse was suspected to be a male pseudohermaphrodite but the gonads were not examined. One horse was suspected to be affected by an XX-sex several syndrome and in one case a SRY-negative XY-sex reversal syndrome was most likely. In the case of an XX-sex reversal syndrome, there is a female chromosomal constitution, an uterus and cranial parts of the vagina are present but also testes tissue and possibly an enlarged penis like clitoris. Here an XX-sex reversal syndrome was suspected but not confirmed as it was not possible to examine the gonads and verify tissue from testes. Therefore a pseudohermaphroditismus femininus could not be excluded. In cases of XY-sex reversal syndrome the patients show a male chromosomal constitution, parts of a female reproductive tract but no testes tissue is present. For the horse described here, a deletion of the SRY gene was the most likely cause for the XY-sex reversal syndrome.
Sex chromosome anomalies are frequently expressed as malformations of the
reproductive organs and constitute sporadic birth defects in domestic animals, which
often leads to infertility. In the presence of a normal karyotype, abnormalities in the
genital tract development can occur. Intersex condition is relatively frequent in goats and
pigs, but less frequent in sheep and dogs. In ruminants, most intersexes conditions
correspond to XX/XY haematopoietic chimaeras and fit in the freemartinism syndrome.
However, sporadically cases of male pseudohermaphroditism are reported that can be
differentiated from the freemartinism syndrome through the karyotype as well as by the
morphological characteristics of the genital tract. These are XY animals that evidence a
variable differentiation of the genital tract, owing to varying degrees of the external
genitalia and paramesonephric ducts associated with inadequate production of
testosterone or Anti-Müllerian Hormone by the fetal testes. Male pseudohermaphroditism
may occur in distinct varieties. Male pseudohermaphroditism includes male to female sex
reversal a condition where, consecutive to a disrupted gonadal differentiation or to an
abnormal development of the Leydig cells, testosterone production is impaired; this
syndrome may present distinct clinical gradations, whether a streak gonad or a
dysgenesic gonad develops. Total absence of androgens induces feminization of the
reproductive tract, while impaired testosterone production and accumulation of
testosterone precursors may originate ambiguous genitalia. In the androgen insensitivity
syndrome, another form of male pseudohermaphroditism also called the testicular
feminization syndrome, despite the presence of testes and a XY karyotype, almost
normal-appearing female phenotypes can be found. This condition is associated to a
defect in the androgen receptor mechanism that leads to a resistance to the testosterone
action at the cellular level in the external genitalia embryonic rudiments. A steroid 5α-reductase deficiency, impairing dihydrotestosterone formation, might also be responsible
for male pseudohermaphroditism. Frequently, animals usually are XY individuals
evidencing female-like or ambiguous external genitalia. Persistency of the Müllerian
ducts is another male pseudohermaphroditism condition, associated with the inadequate
production of Anti-Müllerian Hormone or to the absence of its receptors, which can
reveal female or ambiguous external genitalia.
Based on three distinct forms of male pseudohermaphroditism recently evaluated by
our Clinical Services, the aims of this study includes the morphological, histological and
immunohistochemical description of this condition in normal XY karyotype males (in
both blood and fibroblast samples), and the discussion of the cases through a review of
the literature, in order to improve our knowledge of male pseudohermaphroditism.
Inherited disorders of sexual development (DSD) cause sterility and infertility in horses. Mutations causing such disorders have been identified in other mammals, but there is little information on the molecular causes in horses. While the equine genome sequence has made it possible to identify candidate genes, additional tools are needed to routinely screen them for causative mutations. In this study, we designed a screening panel of polymerase chain reaction primer pairs for 15 equine genes. These are the candidate genes for testicular or ovotesticular XX DSD and XY DSD, the latter of which includes gonadal dysgenesis, androgen insensitivity syndrome (AIS), persistent Mullerian duct syndrome and isolated cryptorchidism. Six horses with testicular or ovotesticular XX DSD and controls were screened. In addition, candidate genes for androgen insensitivity syndrome, persistent Mullerian duct syndrome and isolated cryptorchidism were screened in normal horses. While no sequence variants were uniquely associated with XX DSD, the 38 sequence variants identified can serve as intragenic markers in genome-wide association studies or linkage studies to hasten mutation identification in equine XX DSD and XY DSD.
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.
2 Standardbred racehorses that had been winning races while competing as mares underwent postrace drug testing and had serum testosterone concentrations above the acceptable limit for female racehorses.
Initial physical examinations by the referring veterinarian revealed ambiguous external genitalia and suspected intra-abdominally located testes leading to a preliminary diagnosis of male pseudohermaphroditism. Horses were referred for further evaluation of sex. Physical examination of the external genitalia confirmed the findings of the referring veterinarian. Transrectal palpation and ultrasonography revealed gonads with an ultrasonographic appearance of testes. On cytogenetic analysis, both horses were determined to have a 64,XY karyotype and 8 intact Y chromosome markers and 5 SRY gene markers, which were indicative of a genetic male and confirmed an intersex condition. Additionally, both horses had some male-type behavior and endocrinologic findings consistent with those of sexually intact males.
Taken together, these findings confirmed that both horses were male pseudohermaphrodites. Both horses returned to racing competition as males.
As of October 1, 2008, the Pennsylvania Horse and Harness Racing Commissions implemented a postrace drug testing policy that included analysis of blood samples for anabolic and androgenic steroids and set maximum allowable concentrations of testosterone for racing geldings and females. Within 8 months of initiation of this drug testing policy, the 2 horses of this report were identified as having an intersex condition. This raises the possibility that intersex conditions may be more common in racing Standardbreds than was previously suspected.
We described the clinical, cytogenetic and molecular findings of 17 clinical equine cases presented for abnormal sexual development and infertility. Six horses with an enlarged clitoris had an XX, SRY-negative genotype, which displayed male-like behavior (adult individuals). Bilateral ovotestes were noted in 2 of those cases, while another case showed increased levels of circulating testosterone. Six horses with a female phenotype, including normal external genitalia, had an XY, SRY-negative genotype. These individuals had small gonads and an underdeveloped internal reproductive tract. Four horses with normal appearing external genitalia had an XY, SRY-positive genotype, 3 of them had hypoplastic testes and male-like behavior. In addition, one young filly with enlarged clitoris and hypoplastic testes had the same genotype but did not show male-like behavior due to her age. Three of these horses were related with 2 being siblings. These findings demonstrate the diversity of disorders of sexual development seen in the horse. Furthermore, they emphasize the need for further research to identify genes involved in abnormal sex determination and differentiation in the horse.
Our knowledge on the many aspects of mammalian reproduction in general and equine reproduction in particular has greatly increased during the last 15 years. Advances in the understanding of the physiology, cell biology, and biochemistry of reproduction have facilitated genetic analyses of fertility. Currently, there are more than 200 genes known that are involved in the production of fertile sperm cells. The completion of a number of mammalian genome projects will aid in the investigation of these genes in different species. Great progress has been made in the understanding of genetic aberrations that lead to male infertility. Additionally, the first genetic mechanisms are being discovered that contribute to the quantitative variation of fertility traits in fertile male animals. As artificial insemination (AI) represents a widespread technology in horse breeding, semen quality traits may eventually become an additional selection criterion for breeding stallions. Current research activities try to identify genetic markers that correlate to these semen quality traits. Here, we will review the current state of genetic research in male fertility and offer some perspectives for future research in horses.
Cytogenetic and molecular genetic studies of an intersex horse have been carried out. The investigated animal had overall male body conformation; however, its external genitalia consisted of incompletely developed vulva and penis. The X and Y chromosome painting probes detected three cell lines in the examined horse: 63,X, 64,XX and 65,XX with a fragment of a Y chromosome (del Y). The DNA analysis with the PCR and PCR/RFLP methods showed absence of SRY,AMELY and ZFY genes as well as of six Y microsatellite markers (YM2, YP9, YJ10, YE1, YH12, and YA16). These results suggest that the Y chromosome fragment detected in the investigated animal was the result of a deletion of a euchromatic fragment comprising the above-mentioned markers.
A sex-reversal syndrome appears frequently in the horse. The mare carriers of this syndrome lack of SRY gene. It is suggested that sex-reversal syndrome is probably caused by transfer of the SRY gene from Y to the X chromosome, due to abnormal meiotic exchange. The aim of the study was molecular analysis of the Y-linked genes in a case of the sex-reversed infertile mare with 64,XY karyotype. The karyotype was established on the basis of analysis of 350 metaphase spreads stained by CBG banding. Molecular analysis of the loci assigned to the Y chromosome revealed absence of the SRY gene and presence of the other studied loci (ZFY, AMEL-Y and STS-Y). In this animal all fragments representing X chromosome (ZFX, AMEL-X and STS-X) were detected. External genitalia in the mare were normal, uterus was small and ovaries (examined by ultrasonography) extremely small. The mechanism of sex-reversal syndrome formation was discussed. It is postulated that during spermatogenesis in the sire two crossing-over events between the X and Y chromosomes occurred. One of them took place between the ZFY and SRY loci and another one between the SRY locus and the centromere.
Cytogenetic abnormalities
- At Bowling
- Hughes
- Ao Mckinnon
- Voss
Bowling AT, Hughes JP. Cytogenetic abnormalities. In: McKinnon AO, Voss JL, eds. Equine Reproduction. Philadelphia: Lea & Febiger, Voss JL, eds. Equine Reproduction. Philadelphia: Lea & Febiger, 1993:258–261.