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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.
From cytogenetics to cytogenomics: a new era in the diagnosis of chromosomal abnormalities in domestic animals
Transcript Patterns of Bovine CYP21A2 and Its Pseudogene in Adrenal and Ovarian Tissues
Background: The cytochrome P450 family 21 subfamily A member 2 gene (CYP21A2) encodes 21-hydroxylase, a key enzyme in adrenal steroid biosynthesis. Despite its physiological importance, the diversity of CYP21A2 transcript variants and their tissue-specific expression in domestic animals, including cattle, remains largely unexplored. This study aimed to characterize CYP21A2 transcription in adrenal glands and ovaries and assess the potential transcriptional activity of its pseudogene, CYP21A1P. Methods: CYP21A2 transcription was investigated in adrenal and ovarian tissues of 12 healthy cows using semi-quantitative PCR and Sanger sequencing. Real-time PCR was performed to confirm expression levels. Melting curve analysis and electrophoresis were used to validate distinct amplicons corresponding to different transcript variants. Extended amplicons were sequenced to identify transcripts corresponding to reference sequences and potential pseudogene products. Results: A single transcript variant (NM_001013596.1) was consistently detected in adrenal glands, whereas ovaries expressed two variants: NM_001013596.1 and XM_024983378.2. Semi-quantitative analysis showed significantly higher CYP21A2 expression in adrenal glands compared to ovaries (p < 0.01). In ovarian samples, the NM_001013596.1 variant was more abundant than the XM_024983378.2 (p < 0.01). Sanger sequencing revealed two products matching CYP21A2 reference transcripts and an additional, longer product containing sequence motifs specific to the pseudogene CYP21A1P, indicating its transcriptional activity. Conclusions: These results provide the first evidence of tissue-specific expression and differential abundance of CYP21A2 transcript variants in cattle and suggest the transcription of the CYP21A1P pseudogene. The findings reveal the complexity of CYP21A2 expression in steroidogenic tissues and suggest potential regulatory roles for transcript and pseudogene variants in bovine physiology.