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Elevated serum concentration of anti‐Mullerian hormone and its association with SNP variants in the AMH gene in a tortoiseshell tomcat with a disorder of sex development (38,XX; SRY-negative)
AbstractTesticular disorders of sex development (DSD) in cats with XX sex chromosomes and the absence of the SRY gene are rare congenital abnormalities. A Maine Coon tomcat with a normal penis, gonads in the scrotum, low serum testosterone concentration, and an elevated level of anti‐Müllerian hormone (AMH) was subjected to genetic analyses due to an unusual tortoiseshell coat color for males. Primary studies revealed the presence of XX sex chromosomes, the lack of SRY and the presence of two copies of the candidate SOX9. The DSD tomcat and its parents were analyzed using whole genome sequencing. Candidate SNPs in AMH, ORC1, DOCK8, PRKAR1A, and TMEM186 genes, as well as a known intronic 5‐kb deletion in X‐linked ARHGAP36 gene, which is responsible for orange coat, were identified. Potentially pathogenic homozygous genotypes were observed in all candidate genes; however, only in AMH and ORC1 were these genotypes rare in a control cohort. Further studies were focused on two SNPs located in the 5′‐and 3′‐untranslated regions (UTRs) of AMH. It has been experimentally demonstrated that only a short AMH transcript is present in feline testes. In silico analysis revealed that the SNP located in the 3′UTR of AMH occurs within a sequence that partially matches the canonical binding site for human miR‐5571‐5p. This microRNA is expressed in mammalian testes, which we confirmed in feline testicular tissue. We concluded that SNP in the 3′UTR of AMH is associated with elevated expression of the encoded hormone; however, it is not the cause of the testicular DSD phenotype in the studied Maine Coon tomcat.
Testicular Disorder of Sex Development in a Mare With a Low Incidence of SRY‐Positive Cell Line in the Gonads
ABSTRACTAn adult mare with ambiguous external genitalia, observed at a slaughterhouse, was subjected to detailed examination. The mare exhibited fused labia and an enlarged clitoris located at the ventral commissure of the vulva. Anatomical and histopathological studies revealed the presence of two testicles, vas deferens, fallopian tubes, a small uterus with blindly ending horns and a normally developed cervix. Cytogenetic analysis, using fluorescent in situ hybridisation (FISH) of in vitro cultured lymphocytes, showed a female karyotype—64,XX. Molecular detection of X‐ and Y‐linked genes (SRY and ZFX/ZFY) in blood cells confirmed the presence of X‐linked genes only. In contrast, in hair follicles and gonadal tissue, the presence of genes originating from the Y chromosome was also detected. The use of digital droplet PCR (ddPCR) revealed the presence of a SRY‐positive cell line; however, at a very low level (< 5%). Analysis of polymorphic short tandem repeats (STRs), recommended for parentage testing, did not detect chimerism, which would be indicated by the presence of three or four variants at some STR loci. In conclusion, the studied case was classified as a sex chromosome disorder of sex development (DSD) due to gonadal XX/XY mosaicism. To the best of our knowledge, this is the first reported case of such an abnormality in a DSD horse.
SOX9 gene variants in 27 French Bulldogs with disorder of sex development (XX, SRY-negative): identification of first case of skeletal abnormalities associated with SOX9 triplication
Copy number variation of the SRY gene showed an association with disorders of sex development in Yorkshire Terrier dogs
SummaryThe molecular background of disorders of sex development (DSD) in dogs is poorly understood. Several copies of the SRY genes have been reported in the dog genome. We used droplet digital PCR with the aim of determining variability in SRY copy number and its association with DSD in dogs. Altogether 19 DSD male dogs (XY DSD) of 10 breeds and 87 control dogs of eight breeds were analyzed. Moreover, we performed a comparative analysis of SRY copy number in other canids: wolves (3), red foxes (16), and Chinese raccoon dogs (10). We found that the modal number of SRY copies in dogs, wolves, red foxes, and Chinese raccoon dogs was 3, 3, 1, and 3 respectively. Variability of copy number was only observed in Yorkshire Terriers (two or three copies) and red foxes (one or two copies). An analysis of six DSD Yorkshire Terriers and 38 control males of this breed showed that 50% of the DSD dogs had two copies, while the incidence of this variant was significantly lower in the control dogs (10.5%). Searching for the copy number of the coding and 5′‐flanking fragments revealed full concordance with the copy number. These fragments were also sequenced in DSD (19) and control (24) dogs, and no DNA variants were found. We conclude that, in the dog, two or three functional copies of the SRY gene are present, and a smaller number of copies showed an association with the risk of DSD phenotype in Yorkshire Terriers.
XX/XY Chimerism in Internal Genitalia of a Virilized Heifer
Five DSD heifers underwent genetic analysis in the present study. We cytogenetically analyzed in vitro cultured leukocytes and searched for SRY, AMELX/AMELY and ZFX/ZFY genes in leukocytes and hair follicles, finding that four of the studied heifers were freemartins (XX/XY leukocyte chimerism). The fifth case had an underdeveloped vulva localized ventrally and cranially to the mammary gland, a normal female sex chromosome complement (60,XX) in the leukocytes, and a lack of Y-chromosome-derived genes in the leukocytes and hair follicles. Postmortem anatomical examination of this heifer revealed the presence of normal ovaries with follicles, uterus, and oviducts, but molecular detection of the SRY, ZFX, ZFY,AMELX, and AMELY genes in these organs indicated the presence of a cell line carrying the Y chromosome. Further analysis of twelve microsatellite markers revealed the presence of additional variants at six loci in DNA samples derived from the reproductive organs; XX/XY chimerism was thus suspected in these samples. On the basis of the detection of AMELY (Y-linked) versus AMELX (X-linked) and SOX9 (autosomal) versus AMELY genes by droplet digital PCR (ddPCR), the Y/X and Y/autosome ratios were evaluated; they indicated the presence of XX and XY cell lines in the reproductive tissues. Our study showed that XX/XY chimerism can be present in the internal reproductive organs of the virilized heifers with a normal female set of sex chromosomes (60,XX) and a lack of Y-chromosome-derived genes in the leukocytes. The etiology of this phenomenon remains unknown.
Non-mosaic X monosomy (77,X) in a female dog with signs of virilization
AbstractA 14-month-old female Miniature Poodle dog with an enlarged clitoris and asymmetry in the placement of the teats was subjected to clinical, histopathological, and genetic studies. Macroscopically, the uterus and fallopian tubes appeared normal, while both ovaries were diffusely altered. At histology, the ovarian parenchyma was almost completely effaced by a diffuse hyperplasia of theca cells with atretic primary follicles. Chromosome analysis showed pure (non-mosaic) X monosomy (77,X). This finding was confirmed by the highly sensitive droplet digital PCR (ddPCR) approach. Despite the observed virilization, molecular analysis did not show the presence of Y-linked genes (SRY,ZFY, andTSPY1) in the blood cells or ovary tissue. To the best of our knowledge, this is the first case of X monosomy in a dog associated with virilization.