Localisation of the Y chromosome stature gene to a 700 kb interval in close proximity to the centromere

A 46,XX Karyotype in Men with Infertility: Two New Cases and Review of the Literature

46,XX male sex reversal syndrome is a rare genetic cause of male infertility. We report on two new cases of this syndrome in men presenting with hypogonadism and infertility. Cytogenetic and molecular analysis was performed in both patients. An extensive review of the literature for 46,XX male sex reversal syndrome cases related to infertility was also performed to fully characterise this syndrome. Genetic analyses showed translocation of the SRY on Xp chromosome and complete absence of all Azoospermia factor (AZF) genetic regions. All patients included in the review presented hypergonadotropic hypogonadism. Small testes were the most common clinical characteristic present in 90.2% of the patients, followed by small penis (31.8%), gynecomastia (26.8%) and poor hair distribution (15.4%). The presence of the SRY was identified in 130/154 (84.4%) patients: in 98.5% of cases, it was translocated on the Xp chromosome and in 1.5% on an autosome. All patients were azoospermic, due to the lack of AZF genetic regions. Males with normal phenotype and primary hypogonadism should be properly evaluated by the physicians and must be referred for cytogenetic and molecular analysis to exclude or confirm 46,XX male sex reversal syndrome. More cases of this syndrome with SRY translocated on an autosome are needed to identify if these patients have different characteristics than those with SRY translocated on Xp chromosome. Whole genome analysis of these patients is required to elucidate the genetic differences which are responsible for the phenotypic variability of the syndrome.

Unbalanced Y;7 Translocation between Two Low-Similarity Sequences Leading to SRY-Positive 45,X Testicular Disorders of Sex Development

Unbalanced translocations of Y-chromosomal fragments harboring the sex-determining region Y gene (SRY) to the X chromosome or an autosome result in 46,XX and 45,X testicular disorders of sex development (DSD), respectively. Of these, Y;autosome translocation is an extremely rare condition. Here, we identified a 20-year-old man with a 45,X,t(Y;7)(q11.21;q35) karyotype, who exhibited unilateral cryptorchidism, small testis, intellectual disability, and various congenital anomalies. The fusion junction of the translocation was blunt, and the breakpoint-flanking regions shared only 50% similarity. These results indicate that Y;autosome translocations can occur between 2 low-similarity sequences, probably via nonhomologous end joining. Furthermore, translocations of a Ypterq11.21 fragment to 7q35 likely result in normal or only mildly impaired male-type sexual development, along with various clinical features of 7q deletion syndrome, although their effects on adult testicular function remain to be studied.

Clinical and genetic analysis in males with 46,XX disorders of sex development: A reproductive centre experience of 144 cases

To explore the clinical features and assisted reproductive technology (ART) outcomes of 46,XX disorders of sex development (DSD) males, 144 males with 46,XX DSD were recruited in this retrospective study. The baseline information, clinical characteristics and ART outcomes of the participants were collected and analysed. The mean age was 29.06 ± 4.50 years. The mean volumes (95% CI) of left and right testicles were 2.16 (1.82-2.49) ml and 2.16 (1.83-2.49) ml, respectively. Cryptorchidism and/or hypospadias appeared in 19 patients (13.19%). Elevated levels of follicle-stimulating hormone (FSH) were found in 136 patients (95.10%) and increased luteinising hormone (LH) values were detected in 125 patients (92.59%). Eighty subjects (62.99%) had low testosterone values. Among 86 patients with status of sex-determining region Y (SRY)-gene and azoospermia factor (AZF) region available, fifteen (17.44%) patients were SRY-negative and AZF region was absent in every patient without exception. Additionally, fertility achieved in 87 patients through ART using donor spermatozoa. In conclusion, hypergonadotropic hypogonadism appeared as the main presentation of 46,XX DSD males regardless of the SRY status. The available fertility option proved to achieve live birth was limited to ART using donor spermatozoa.

Clinical, cytogenetic, and molecular analysis with 46,XX male sex reversal syndrome: case reports

PURPOSE

To investigate the clinical characteristics of different categories of sex-reversed 46,XX individuals and their relationships with chromosomal karyotype and the SRY gene.

METHODS

Chromosome karyotyping for peripheral blood culture and multi-PCR and FISH were performed.

RESULTS

Endocrinological data showed that their endocrine hormone levels were similar to that observed for Klinefelter syndrome, with higher FSH and LH levels and lower T levels. Chromosome karyotyping for peripheral blood culture revealed 46, XX complement for 11 males. Molecular studies showed that there were locus deletions at SY84, SY86, SY127, SY134, SY254 and SY255 in AZF on chromosome Y in 9 cases, with the SRY gene present at the terminus of the X chromosome short arm. In one case, besides 6 locus deletions in AZF, there was also SRY gene deletion. In another case, there were locus deletions only at SY254 and SY255, with SY84, SY86, SY127 SY134 loci and SRY present.

CONCLUSIONS

The majority (10/11) of 46,XX males were SRY positive, with the SRY gene translocated into the terminus of the X chromosome short arm. These patients were caused mainly by an X/Y chromosomal inter-change during paternal meiosis, leading to the differentiation of primary gonads into testes. Only a single patient (1/11) was SRY-negative, in which there might be some unknown downstream genes involved in sex determination.

A case report of an incidental finding of a 46,XX, SRY-negative male with masculine phenotype during standard fertility workup with review of the literature and proposed immediate and long-term management guidance

OBJECTIVE

To describe and explore the current literature on the rare genetic condition of 46,XX SRY-negative males. In addition, we propose comprehensive clinical guidelines in the management of this condition to aid fertility clinicians in their management of affected individuals.

DESIGN

Case report with expert consensus-derived clinical management guidance.

SETTING

Fertility outpatient clinic at a tertiary referral center.

PATIENT(S)

A 40-year-old male found to have 46,XX disorder of sex development (DSD) on routine fertility screening.

INTERVENTION(S)

A review of the literature, expert consultation, and formulation of comprehensive clinical guidance.

MAIN OUTCOME MEASURE(S)

We report an interesting and rare case of a phenotypical male with the karyotype 46,XX DSD without an SRY region. There is limited literature exploring this condition, and its etiology remains poorly understood. There is currently no clinical guidance available for fertility clinicians to follow when treating this condition.

RESULT(S)

A male phenotype with a 46 karyotype without the sex-defining region of the Y chromosome.

CONCLUSION(S)

A multidisciplinary approach should be adopted in the management of 46,XX individuals. All patients with azoospermia must be karyotyped. Sperm donation remains the only fertility treatment available. The 46,XX patients need lifelong followup led by an endocrinologist with regular imaging of the gonads, bone density measurements, baseline blood tests, and T supplementation. Psychological support is a key part of a holistic approach.

45,X maleness: clinical and cytogenetic features in two patients

45,X maleness is a very rare disorder. We report on 2 new 45,X males aged 9 10/12 and 39 years, respectively. The boy presented for developmental delay, while the man was referred to us because of infertility. Both patients showed short stature (boy -2.29 SDS, man -4.05 SDS) and an unbalanced translocation of Yp, including SRY, onto the long arm of chromosome 10 and short arm of chromosome 14, respectively. The growth pattern of the 2 patients and literature data suggest the presence of a specific growth gene in the pericentrometric region of Yq. In addition, developmental delay in some 45,X males may be related to specific deletion of telomeric autosome regions, but involvement of gene(s) on the Y chromosome may play a role as well. Albeit in the boy inhibin B levels were in the normal range for age, azoospermia was demonstrated in the adult, supporting that infertility is a feature of adult 45,X men with AZFa-c deletion.

Prenatal detection of a de novo Yqh-acrocentric translocation

OBJECTIVES

To identify the extra chromosomal material on 46,XX,21p+ for prenatal diagnosis.

DESIGN AND METHODS

Conventional cytogenetic studies using GTG (G bands by trypsin using Giemsa) and CBG (C bands by barium hydroxide using Giemsa) techniques were performed on chromosomes at metaphase obtained from cultured amniocytes and parental blood lymphocytes. Molecular cytogenetic techniques, QF-PCR (quantitative fluorescent polymerase chain reaction), FISH (fluorescent in-situ hybridization), and DA-DAPI (Distamycin A and 4,6-diamino-2-phenylindole) staining, were then used to clarify the extra material present on fetal chromosome 21 p.

RESULTS

The extra material on fetal chromosome 21 p has originated from Yqh, most likely at PAR2 (the secondary pseudoautosomal region). The karyotype should be 46,XX,der(21)t(Y;21)(q12;p13)de novo.ish der(21)t(Y;21)(q12;p13) (EST Cdy16c07+).

CONCLUSION

This case demonstrates the usefulness of molecular techniques in the investigation of rare chromosomal rearrangements.

Isochromosome of Yp in a man with Sertoli-cell-only syndrome

OBJECTIVE

To address phenotype/genotype correlation in a man with i(Y)(p10).

DESIGN

Case report.

SETTING

University-based reproductive genetics laboratory.

PATIENT(S)

A 27-year-old azoospermic man with i(Y)(p10), relatively normal stature, and testicular Sertoli-cell-only syndrome.

INTERVENTION(S)

Testicular biopsy, cytogenetic study, Y-chromosome deletion mapping analysis, fluorescence in situ hybridization (FISH).

MAIN OUTCOME MEASURE(S)

Expression of Y-chromosome genes.

RESULT(S)

We have identified one azoospermic man with i(Y)(p10) of 312 Taiwanese men presenting with a severe spermatogenic defect. Y-chromosome deletion mapping analysis confirmed deletions of all Yq sequences, including a putative growth controlling gene. Fluorescence in situ hybridization (FISH) analysis showed duplication of Yp material. The patient had normal stature considering midparental height. He also had no germ cells in the testicular tissue (Sertoli-cell-only syndrome) resulting from the loss of azoospermia factor in Yq.

CONCLUSION(S)

Among structural rearrangements of the Y-chromosome, the isochromosome of Yp occurs very rarely. This case is the first reported case of an isochromosome Yp with a detailed description of testicular histology and body height.

Interchromosomal segmental duplications of the pericentromeric region on the human Y chromosome

Basic medical research critically depends on the finished human genome sequence. Two types of gaps are known to exist in the human genome: those associated with heterochromatic sequences and those embedded within euchromatin. We identified and analyzed a euchromatic island within the pericentromeric repeats of the human Y chromosome. This 450-kb island, although not recalcitrant to subcloning and present in 100 tested males from different ethnic origins, was not detected and is not contained within the published Y chromosomal sequence. The entire 450-kb interval is almost completely duplicated and consists predominantly of interchromosomal rather than intrachromosomal duplication events that are usually prevalent on the Y chromosome. We defined the modular structure of this interval and detected a total of 128 underlying pairwise alignments (>/=90% and >/=1 kb in length) to various autosomal pericentromeric and ancestral pericentromeric regions. We also analyzed the putative gene content of this region by a combination of in silico gene prediction and paralogy analysis. We can show that even in this exceptionally duplicated region of the Y chromosome, eight putative genes with open reading frames reside, including fusion transcripts formed by the splicing of exons from two different duplication modules as well as members of the homeobox gene family DUX.

A 46,XX -negative man with complete virilization and infertility as the main anomaly

OBJECTIVE

To report a case of a 46,XX SRY-negative man with a male phenotype and azoospermia.

DESIGN

Case report.

SETTING

Molecular and Cytogenetic Unit in a University Hospital.

PATIENT(S)

A 35-year-old man with complete masculinization who referred to our institution because of a history of several years of infertility.

INTERVENTION(S)

Lymphocytic karyotype and genetic counseling.

MAIN OUTCOME MEASURE(S)

Peripheral blood metaphases were analyzed by standard G-banding and Q-banding. Fluorescent in situ hybridization (FISH) and polymerase chain reaction (PCR) analyses were performed.

RESULT(S)

Semen analysis showed azoospermia. Chromosome analysis revealed a 46,XX karyotype; molecular and cytogenetic analyses excluded the presence of SRY (the sex-determining region of the Y chromosome) gene.

CONCLUSION(S)

This case is one of the rare patients reported in the literature in whom testicular differentiation and a complete virilization in a 46,XX chromosomal constitution does not account for a translocation of the SRY gene to the X chromosome or to the autosomes. This finding suggests that other genes downstream from SRY, not yet identified, play an important role in sex determination.