Genes in the Azoospermia Factor A Region of the Y Chromosome Show Sexual Dimorphism in Rat Brain Prior to Gonadal Sex Differentiation

BackgroundThe classical concept of brain sex differentiation suggests that steroid hormones released from the gonads program male and female brains differently. However, several studies indicate that steroid hormones are not the only determinant of brain sex differentiation and that genetic differences could also be involved.MethodsIn this study, we have performed RNA sequencing of rat brains at embryonic days 12 (E12), E13, and E14. The aim was to identify differentially expressed genes between male and female rat brains during early development. ResultsAnalysis of genes expressed with the highest sex differences showed that Xist was highly expressed in females having XX genotype with an increasing ratio over time. Analysis of genes expressed with the highest male expression identified three main genes. At E12, two genes located in the azoospermia factor A (AZFa) region on the Y chromosome were highly expressed in males. These were Ddx3y (1552-fold higher in males) and Kdm6c (147-fold higher in males). The expression of Kdm6c, but not Ddx3y, remained high at both E13 and E14. In qRT-PCR analysis, these two genes were highly expressed in all the stages in male brain. In addition to these genes, one of the several copies of Sry in the rat genome, Sry4, showed a high expression in the male brains at all three time points. At all three time points several other genes were also found to show sex bias, but with lower differences in gene expression. ConclusionThe observed sex-specific expression of genes at early development suggests that the rat brain is sexually dimorphic prior to gonadal action on the brain and identifies the AZFa region genes as a possible contributor to male brain development.

An Infertile Azoospermic Male with 45, X T(Yp;15) Karyotype

Objective: 45, X is a very rare condition that usually results from Y/autosomal translocations or insertions. Here we present an infertile azoospermic man who had 45, X t(Yp;15) karyotype and deletion of AZF (azoospermia factor) gene region. Case report: A 35-year-old infertile azoospermic man with a typical male appearance came for infertility genetic counseling. He was infertile for more than ten years and had short height. High-resolution of metaphase chromosomes of 50 peripheral white blood cells were analyzed for karyotyping. Fluorescence in situ hybridization (FISH) analysis and Polymerase chain reaction (PCR) were done for SRY and AZF gene localization. Karyotyping and FISH analysis revealed 45, X t(Yp;15) karyotype and no mosaicism. More investigation on the Y chromosome revealed no deletion in the SRY region, but AZF a/b/c were deleted. It was revealed that Yp's subtelomeric region but not Yq was translocated to chromosome 15. Conclusion: This study shows that despite the lack of a complete Y chromosome in this person, the occurrence of secondary male traits is a result of the short arm translocation of the Y chromosome, which contains the (ex-determining region Y) SRY gene. Infertility is also due to the Y chromosomes long arm's deletion containing the AZF gene region.

Cellular and Molecular Genetic Analysis of 1980 Male Infertility Patients

Background The aims of this study were to investigate the distribution of chromosome karyotype abnormality and azoospermia factor (AZF) microdeletion on Y chromosome in male infertility patients and its effect on infertility. Further, the study aimed to guide fertility in patients. Methods A total of 1980 azoospermic and oligoospermic male infertility patients were selected from the male outpatient department of our hospital from January 2016 to December 2019. Peripheral blood was collected from the patients for karyotype analysis. Further, AZF microdeletion analysis on Y chromosome was performed by capillary electrophoresis. Results Among the patients of male infertility, 178 had chromosomal abnormality (8.99%, 178/1980). Among them, 98 had an abnormal chromosome number. Among the 98 patients, 47, XXY was the most common (80 cases), accounting for 44.99 % (80/178) of abnormal karyotypes. There were 211 cases of AZF microdeletion on Y chromosome, with a total deletion rate of 10.66% (211/1980). The most common type was AZFb/c deletion (sY1192 140 cases), accounting for 66.3 % (140/211). Conclusion Karyotype abnormality and AZF gene microdeletion are important causes of male infertility. Men with Yqh-, del(Y) (q11) have a higher risk of AZF microdeletion. Infertility patients should routinely undergo cell and molecular genetic tests to guide patient fertility.

Production of offspring from azoospermic mice with meiotic failure: Precise biparental meiosis within halved oocytes

While the large volume of mammalian oocytes is necessary for embryo development, it can lead to error-prone chromosomal segregation during meiosis. Consequently, a smaller ooplasm might assure better chromosomal integrity of oocytes and embryos, but there is no evidence to support this hypothesis. Here, we show that reducing the ooplasm is 38 beneficial for assisted fertilization using primary spermatocytes, involving 39 synchronous biparental meiosis within oocytes. High-resolution live-imaging analysis revealed that erroneous chromosome segregation occurred in most (90%) spermatocyte-injected oocytes of normal size, but could be ameliorated to 40% in halved oocytes. The birth rate improved remarkably from 1% to 19% (P < 0.0001). Importantly, this technique enabled the production of offspring from azoospermic mice with spermatocyte arrest caused by STX2 deficiency, an azoospermia factor also found in humans. Thus, reduced ooplasmic volume can indeed correct the lethal meiotic errors and might help rescue cases of untreatable human azoospermia with spermatocyte arrest.

Verification of a Cryptic T(Y;15) Translocation in a Male With an Apparent 45,X Karyotype

BackgroundA rare disease is that an individual with a non-chimeric karyotype of 45, X develops into a male. We explored the genetic aetiology of an infertility male with an apparent 45, X karyotype, which was subsequently verified as cryptic translocation between chromosomes Y and 15. MethodsPeripheral blood sample was collected from the patient and subjected to a range of genetic testing, including conventional chromosomal karyotyping, short tandem repeat (STR) analysis for azoospermia factor (AZF) region, fluorescence in situ hybridization (FISH) with specific probes for CSP X/CSP Y, CSP Y/D15Z1/PML and SRY/D15Z1/PML, and chromosomal microarray analysis (CMA) for genomic copy number variations (CNVs). ResultsThe patient was found to have an apparent 45,X karyotype. STR analysis showed that he possessed a short arm of the Y chromosome, including the SRY gene but the absence of a long arm of the Y chromosome, including AZFa+b+c and Yqter. A FISH assay using CSP X and CSP Y probes showed a green signal at the centromere of the X chromosome and a red signal for the Y centromeric sequence on a D-group-sized chromosome. By FISH assaying with D15Z1 and CSP Y probes, chromosomes 15 and Y centromeric signals appeared closely on a single chromosome, as ascertained by the PML control probe. A further FISH assay with D15Z1 and SRY probes revealed a signal of the SRY gene at the end of one arm of chromosome 15. The result of the CMA indicated a deletion with an approximate size of 45.31 Mb spanning from Yq11 to Yter. ConclusionAlthough the 45,X male patient did not harbour an intact Y chromosome, his genome contained the SRY gene derived from the translocation of the Yp, which probably triggered the male differentiation and development. Imbalanced translocations of Yp to other chromosomes can result in short stature and infertility among patients. Delineation of the genetic aetiology can guide early intervention and assisted reproduction in adulthood.

A common 1.6 mb Y-chromosomal inversion predisposes to subsequent deletions and severe spermatogenic failure in humans

Male infertility is a prevalent condition, affecting 5–10% of men. So far, few genetic factors have been described as contributors to spermatogenic failure. Here, we report the first re-sequencing study of the Y-chromosomal Azoospermia Factor c (AZFc) region, combined with gene dosage analysis of the multicopy DAZ, BPY2, and CDYgenes and Y-haplogroup determination. In analysing 2324 Estonian men, we uncovered a novel structural variant as a high-penetrance risk factor for male infertility. The Y lineage R1a1-M458, reported at >20% frequency in several European populations, carries a fixed ~1.6 Mb r2/r3 inversion, destabilizing the AZFc region and predisposing to large recurrent microdeletions. Such complex rearrangements were significantly enriched among severe oligozoospermia cases. The carrier vs non-carrier risk for spermatogenic failure was increased 8.6-fold (p=6.0×10−4). This finding contributes to improved molecular diagnostics and clinical management of infertility. Carrier identification at young age will facilitate timely counselling and reproductive decision-making.

A common 1.6 Mb Y-chromosomal inversion predisposes to subsequent deletions and severe spermatogenic failure in humans

Male infertility is a prevalent condition, concerning 5-10% of men. So far, only some recurrent genetic factors have been described as confident contributors to spermatogenic failure. Here, we report the first re-sequencing study of the Y-chromosomal Azoospermia Factor c (AZFc) region combined with gene dosage and Y-haplogroup determination. In analysing 2,324 Estonian men, we uncovered a novel structural variant as a high-penetrant risk factor to male infertility. The Y lineage R1a1-M458, reported at >20% frequency in several European populations, carries a fixed ∼1.6 Mb long r2/r3 inversion destabilizing the AZFc region and predisposing to recurrent microdeletions. Such complex rearrangements were significantly enriched among severe oligozoospermia cases. The carrier vs non-carrier risk to spermatogenic failure was increased 8.6-fold (p = 6.0 × 10−4). The finding contributes to improved molecular diagnostics and clinical management of infertility. Carrier identification in young age will facilitate timely counselling and reproductive decision-making.

Frequency of Y chromosome microdeletions in Armenian infertile men

Микроделеции длинного плеча Y-хромосомы являются частой генетической причиной мужского бесплодия, связанного с азооспермией и олигозооспермией. В различных этнических группах частота встречаемости микроделеций Y-хромосомы может существенно варьировать, а их спектр иметь определенные особенности. Целью представленного исследования являлось определение частоты и структуры микроделеционных изменений локуса AZF у мужчин армянской национальности с бесплодием для оптимизации диагностических и лечебных мероприятий с применением вспомогательных репродуктивных технологий. The long arm of the Y chromosome microdeletions are common genetic cause of male infertility, related with azoospermia and oligozoospermia. The frequency of various Y-chromosome microdeletions can vary significantly in different ethnic groups and have certain features. The aim of the presented research is to determine the frequency and spectrum of AZF (azoospermia factor) microdeletions in infertile men of Armenian nationality, in order to optimize diagnostic and therapeutic measures using assisted reproductive technologies.