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

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.

A tortoiseshell male cat: chromosome analysis and histologic examination of the testis.

Tortoiseshell coat color is normally restricted to female cats due to X-linkage of the gene that encodes the orange coat color. Tortoiseshell male cats do, however, occur at a low frequency among tortoiseshell cats because of chromosome aberrations similar to the Klinefelter syndrome in man: the extra X chromosome of a 39,XXY karyotype introduces the possibility of an orange and a non-orange allele which produce the mixture of orange and non-orange coat spotting known as tortoiseshell. We analyzed the chromosome complement of a fibroblast culture and did histological examinations of testicular tissue from a tortoiseshell male cat referred to us. Chromosome analysis using RBA-banding consistently revealed a 39,XXY karyotype. Histological examinations of testis biopsies from this cat showed degeneration of the tubules, hyperplasia of the interstitial tissue, and complete loss of germ cells. Immunostaining using anti-vimentin and anti-VASA (DDX4) showed that only Sertoli cells and no germ cells were observed in the testicular tubules. As no sign of spermatogenesis was detected, we conclude that this is a classic case of a sterile, male tortoiseshell cat with a 39,XXY chromosome complement.

The case of an Sry-negative XX male Pug with an inguinal gonad.

A case of intersexuality in a Pug that was bought as a male in a pet shop is described. The dog was presented at the Veterinary Teaching Hospital, University of Turin, for a reddish mass protruding from the prepuce. The mass had the aspect of an enlarged clitoris, with a caudoventral direction and a dorsal urethral ostium. A gonad was palpable in the left inguinal region. Laparotomy confirmed ultrasound detection of an abdominal uterine structure together with the right gonad. The histology of both gonads was similar, showing an exclusively masculine character, with seminiferous tubules lined only by Sertoli cells; the uterus showed a normal histological structure. Karyological analysis revealed a female karyotype (78,XX), and polymerase chain reaction showed the absence of Sry. The diagnosis was an XX male. The pathogenesis of the XX sex reversal syndrome in dogs is not completely understood, as Sry, the master gene regulating testis differentiation, is not present; to date, no genetic cause has been identified for this phenotypic condition in dogs. This case is unusual because the dog showed an inguinal testis, implying a partial activity of the mechanisms leading to abdominal testis translocation along a gubernaculum and transinguinal migration.

Novel cytogenetic finding: an unusual X;X-translocation in Mehsana buffalo (Bubalus bubalis).

Cytogenetic investigations of a phenotypically normal Mehsana river buffalo calf (Bubalusbubalis) revealed an XXY chromosome complement due to X;X-translocation in all screened metaphase plates. The chromosomal anomaly was identified by GTG-banding while CBG- and RBG-banding revealed two heterochromatin blocks and that one of the two X chromosomes was late replicating, respectively. The normal cytogenetic profiles of sire, dam and relatives of the calf suggest that the anomaly could have arisen spontaneously during oogenesis. This is the first report on a male river buffalo calf having an XXY chromosome complement with translocation between the two X chromosomes.

Detection of the XXY trisomy in a bull by using sex chromosome painting probes.

Two cattle chromosome painting probes, identifying X and Y heterosomes, were applied to verify the diagnosis of XXY trisomy in an 8-month-old bull of the Polish Red breed. The probes were obtained after chromosome microdissection and labelled with biotin-16-dUTP. In all metaphase spreads, three fluorescence signals were observed - two X and one Y - confirming the diagnosis of a pure XXY trisomy.

Klinefelter syndrome (39 XXY) in an adult Siberian tiger (Panthera tigris altaica).

Fibroblast cultures of a skin biopsy from an adult intact male Siberian tiger (Panthera tigris altaica) revealed an abnormal standard and G-banded karyotype diploid chromosome number of 2n = 39 XXY due to an extra sex chromosome as opposed to the expected 2n = 38 XY. The tiger was euthanatized 1 yr later due to acute multifocal intervertebral disc disease. Histopathology of the reproductive tract demonstrated a paucity of seminiferous tubules and these were devoid of spermatagonia. An increase in fibrous connective tissue was noted in sections of the prostate and epididymis, and expansion of the fibrous interstitium was observed in the testes.

New cases of XXY constitution in cattle.

The present paper describes two cases of an XXY condition in Chianina cattle. Both young bulls were routinely investigated cytogenetically before entering progeny test stations. Every cell examined in the blood cell cultures showed an XXY constitution. The histological study of the gonads, performed on only one bull, showed degradation of the seminiferous tubules. Only Sertoli cells and hyperplastic interstitial cells were observed.

Detection of the X chromosomes in a Klinefelter boar using a whole human X chromosome painting probe.

In situ hybridization with an X chromosome specific painting probe can be used as a tool for studying the numerical and structural rearrangements of X chromosomes. The commercially available porcine specific X chromosome painting probe is still unable to reliably separate autosomes. However, due to across-species X chromosome homology, the human specific X chromosome painting probe can be used in the identification of X chromosomes in pig metaphases. The commercially available human X chromosome specific painting probe was hybridized to metaphase spreads in a Klinefelter boar with a 2n = 39, XXY karyotype to characterize the X chromosomes. Klinefelter syndrome with its effects on the male reproductive trait such as testicular hypoplasia, is under the genetic control of some sex-linked genes in the extra X chromosome which have escaped the X inactivation process. Chromosome analysis by chromosome painting using fluorescence in situ hybridization may in future be more widely used in veterinary medicine and the selection of breeding animals.

A reassessment of Y chromosomal behaviour in germ cells and Sertoli cells of the mouse as revealed by in situ hybridisation.

In situ hybridisation experiments were carried out to reappraise the state of condensation of the Y chromosome in germ cells and Sertoli cells of the mouse. Previous work had suggested that all testicular cells showed a condensed Y chromosome prior to the adult stage. We now demonstrate that, although the Y chromosome is condensed in pre-pubertal Sertoli cells, it is greatly expanded in primordial germ cells (gonocytes). An expanded Y-signal is first seen in Sertoli cell nuclei at or around day 21 of postnatal development, coinciding with the first appearance of spermatids in the germinal epithelium.

Testicular hypoplasia in a Hereford bull with 61,XXY karyotype: the bovine counterpart of human Klinefelter's syndrome.

A Polled Hereford bull with good libido displayed gross testicular hypoplasia and azoospermia. His left testis weighed 23.6 g, approximately 10% of the testis weight of normal Herefords. Histopathologic examination of the left testis revealed small seminiferous tubules in advanced degeneration and very few with Sertoli cells. The number of Leydig cells was disproportionately large in relation to the seminiferous tubules. From both leucocyte and tissue cultures, the karyotypes were 61, XXY. This bull represents the bovine counterpart of human Klinefelter's syndrome.

An animal model for the XXY Klinefelter's syndrome in man: tortoiseshell and calico male cats.

A review of the chromosome findings in 25 male tortoiseshell or calico (T-C) cats showed a variety of aneuploidy, polyploidy, mosaicism, and chimerism. An XXY-complement was included in the chromosome makeup of 16 of the 25 cats. Almost all of these cats were sterile. Testicular pathologic changes, when recorded, appeared comparable with that of human XXY Klinefelter's syndrome. The findings in 2 male T-C cats were presented as representative models of XXY Klinefelter's syndrome in man. Other findings in human Klinefelter's syndrome have not been looked for in the feline models, but a plan for this is underway. A review also was made of the historical steps leading to our present understanding of the Klinefelter syndrome including the role of Felis catus. An explanation of cat coat-color genetics clarified why "black" and sex-linked "orange" coloration can appear together normally in XX females and in rare males with 2 different X chromosomes. Thus, male T-C cats were only convenient indicators of underlying sex-chromosome aberrations which were occurring completely independent of coloration.