Clinical, Hormonal, and Genetic Evaluation of Idiopathic Nonobstructive Azoospermia and Klinefelter Syndrome Patients.

To investigate the clinical, hormonal, and genetic factors in infertile men with idiopathic nonobstructive azoospermia (NOA) or azoospermic Klinefelter syndrome (KFS), a total of 556 and 96 patients, respectively, were included in this study. All patient samples were analyzed cytogenetically. Serum reproductive hormone levels were measured. Microdeletions in the azoospermia factor (AZF) region of the Y chromosome were detected by multiplex PCR using 16 specific sequence-tagged sites. FSH and LH levels in both NOA and KFS patients were significantly higher than the normal range, and the testosterone level in KFS patients was significantly lower. Ninety-two (95.8%) of the KFS patients showed non-mosaic 47,XXY karyotypes and 47,XXY,inv(9)(p11.1q13); the other KFS patients had mosaic karyotypes of 47,XXY/46,XY, 47,XXY/46,XX, and 47,XXY/48,XXXY/46,XX. Among the 556 idiopathic NOA patients with normal karyotypes, 67 (12.05%) had microdeletions in the AZF region of the Y chromosome. Microdeletions were most frequently detected in the AZFc region, followed by AZFa, AZFb, AZFbc, and partial AZFc deletions. However, Y chromosome microdeletions were not found in any of the azoospermic KFS patients. In view of the hormonal and genetic abnormalities in infertile men with idiopathic NOA and with azoospermic KFS, genetic testing for karyotype, Y chromosome microdeletions, and hormonal parameters is advocated.

Familial X/Y Translocation Encompassing ARSE in Two Moroccan Siblings with Sensorineural Deafness.

Unbalanced translocations involving X and Y chromosomes are rare and associated with a contiguous gene syndrome. The clinical phenotype is heterogeneous including mainly short stature, chondrodysplasia punctata, ichthyosis, hypogonadism, and intellectual disability. Here, we report 2 brothers with peculiar gestalt, short stature, and hearing loss, who harbor an X/Y translocation. Physical examination, brainstem acoustic potential evaluation, bone age, hormonal assessment, and X-ray investigations were performed. Because of their dysmorphic features, karyotyping, FISH, and aCGH were carried out. The probands had short stature, hypertelorism, midface hypoplasia, sensorineural hearing loss, normal intelligence as well as slight radial and ulnar bowing with brachytelephalangy. R-banding identified a derivative X chromosome with an abnormally expanded short arm. The mother was detected as a carrier of the same aberrant X chromosome. aCGH disclosed a 3.1-Mb distal deletion of chromosome region Xp22.33pter. This interval encompasses several genes, especially the short stature homeobox (SHOX) and arylsulfatase (ARSE) genes. The final karyotype of the probands was: 46,Y,der(X),t(X;Y)(p22;q12).ish der(X)(DXYS129-,DXYS153-)mat.arr[hg19] Xp22.33(61091_2689408)×1mat,Xp22.33(2701273_3258404)×0mat,Yq11.222q12 (21412851_59310245)×2. Herein, we describe a Moroccan family with a maternally inherited X/Y translocation and discuss the genotype-phenotype correlations according to the deleted genes.

Increased risk of gonadal malignancy and prophylactic gonadectomy: a study of 102 phenotypic female patients with Y chromosome or Y-derived sequences.

STUDY QUESTION: What is the optimal protocol of management for phenotypic female patients with Y chromosome or Y-derived sequences, in particular for adult patients? SUMMARY ANSWER: Immediate gonadectomy, long-term hormone therapy and psychological care are suggested to be the optimal management for older phenotypic female patients with Y chromosome or Y-derived sequences. WHAT IS KNOWN ALREADY: Phenotypic female patients with Y chromosome or Y-derived sequences are at increasing risk of developing gonadal tumors with age. Early diagnosis and safe guidelines of management for these patients are needed. STUDY DESIGN, SIZE, DURATION: One hundred and two phenotypic women with Y chromosome or Y-derived sequences were included in a straightforward, retrospective-observational study conducted over a period of 26 years from January 1985 to November 2010. PARTICIPANTS/MATERIALS, SETTING AND METHODS: Patients aged 16-34 years presenting to our Academic Department of Gynecology with symptoms of disorders of sex development were subjected to history taking, hormonal evaluation, conventional cytogenetic analysis, PCR, histopathology and immunohistochemistry. Features of the gonads were examined and the outcome of prophylactic gonadectomy evaluated. MAIN RESULTS AND THE ROLE OF CHANCE: Among the patients recruited in our study, 48 patients (47.1%) were diagnosed with complete/partial androgen insensitivity syndrome (CAIS/PAIS) (46XY), 33 cases (32.4%) with gonadal dysgenesis (46XY) and the remaining subjects (20.1%) with mixed gonadal dysgenesis (with sex chromosome structural abnormalities). The total incidence of malignancy was 17.6%. Seventeen patients (16.7%) had gonadoblastoma, while one patient (1.0%) with gonadal dysgenesis had dysgerminoma. Gonadoblastoma were observed in 2/21 patients with sex chromosome structural abnormalities (9.5%), 3/33 patients with gonadal dysgenesis (9.1%), 9/30 patients with CAIS (30.0%) and 3/18 patients with PAIS (16.7%). LIMITATIONS, REASONS FOR CAUTION: Selection bias in this cohort study may affect data interpretation due to the low incidence of disorders of sex development in the general population. WIDER IMPLICATIONS OF THE FINDINGS: The risk for malignant transformation may occur in early life and highly increase with age in patients with Y chromosome or Y-derived sequences. Optimal timing of gonadectomy should be decided by multiple factors including the subgroup of disorder, age and degree of patient's maturity. In addition, gonadal biopsy is suggested when the disease is diagnosed and any evidence of premalignancy warranties gonadectomy. STUDY FUNDING/COMPETING INTEREST(S): This work was supported by the National Key Scientific Research Project (2013CB967404), Natural Science Funds of Zhejiang Province (Y13H04005), Zhejiang Qianjiang talent plan (2013R10027), the Fundamental Research Funds for the Central Universities and Key Projects in the National Science & Technology Pillar Program during the Eleventh Five-Year Plan Period (2012BAI32B04). The authors have no conflicts of interest to declare. TRIAL REGISTRATION NUMBER None.

Evaluating the Farming/Language Dispersal Hypothesis with genetic variation exhibited by populations in the Southwest and Mesoamerica.

The Farming/Language Dispersal Hypothesis posits that prehistoric population expansions, precipitated by the innovation or early adoption of agriculture, played an important role in the uneven distribution of language families recorded across the world. In this case, the most widely spread language families today came to be distributed at the expense of those that have more restricted distributions. In the Americas, Uto-Aztecan is one such language family that may have been spread across Mesoamerica and the American Southwest by ancient farmers. We evaluated this hypothesis with a large-scale study of mitochondrial DNA (mtDNA) and Y-chromosomal DNA variation in indigenous populations from these regions. Partial correlation coefficients, determined with Mantel tests, show that Y-chromosome variation in indigenous populations from the American Southwest and Mesoamerica correlates significantly with linguistic distances (r = 0.33-0.384; P < 0.02), whereas mtDNA diversity correlates significantly with only geographic distance (r = 0.619; P = 0.002). The lack of correlation between mtDNA and Y-chromosome diversity is consistent with differing population histories of males and females in these regions. Although unlikely, if groups of Uto-Aztecan speakers were responsible for the northward spread of agriculture and their languages from Mesoamerica to the Southwest, this migration was possibly biased to males. However, a recent in situ population expansion within the American Southwest (2,105 years before present; 99.5% confidence interval = 1,273-3,773 YBP), one that probably followed the introduction and intensification of maize agriculture in the region, may have blurred ancient mtDNA patterns, which might otherwise have revealed a closer genetic relationship between females in the Southwest and Mesoamerica.

Remarkably little variation in proteins encoded by the Y chromosome's single-copy genes, implying effective purifying selection.

Y-linked single-nucleotide polymorphisms (SNPs) have served as powerful tools for reconstructing the worldwide genealogy of human Y chromosomes and for illuminating patrilineal relationships among modern human populations. However, there has been no systematic, worldwide survey of sequence variation within the protein-coding genes of the Y chromosome. Here we report and analyze coding sequence variation among the 16 single-copy "X-degenerate" genes of the Y chromosome. We examined variation in these genes in 105 men representing worldwide diversity, resequencing in each man an average of 27 kb of coding DNA, 40 kb of intronic DNA, and, for comparison, 15 kb of DNA in single-copy Y-chromosomal pseudogenes. There is remarkably little variation in X-degenerate protein sequences: two chromosomes drawn at random differ on average by a single amino acid, with half of these differences arising from a single, conservative Asp-->Glu mutation that occurred approximately 50,000 years ago. Further analysis showed that nucleotide diversity and the proportion of variant sites are significantly lower for nonsynonymous sites than for synonymous sites, introns, or pseudogenes. These differences imply that natural selection has operated effectively in preserving the amino acid sequences of the Y chromosome's X-degenerate proteins during the last approximately 100,000 years of human history. Thus our findings are at odds with prominent accounts of the human Y chromosome's imminent demise.

A single-nucleotide polymorphism of the DAZL gene promoter confers susceptibility to spermatogenic failure in the Taiwanese Han.

BACKGROUND: Deleted in AZoospermia-like (DAZL) is an autosomal homologue of Y chromosome-linked DAZ gene located on chromosome 3p24. DAZL is only expressed in the gonads and is critical to germ cell development in different species. However, the regulation of DAZL has not been explored. METHODS: Reporter assays, electrophoretic mobility shift assays, supershift assays and bisulfate sequencing were used to identify the core promoter region of DAZL. Sequence analysis was used to identify single-nucleotide polymorphisms (SNPs) in the promoter region. A total of 337 infertile men with abnormal semen parameters and 203 fertile men with normal semen parameters were subjected to sequence analysis of the DAZL promoter region. RESULTS: The DAZL gene core promoter is located 1 kb upstream of the transcription start site. Three SNPs (-792G>A, -669A>C and -309T>C) were identified in our population. Of these three SNPs, -792G>A was more prevalent in the infertile men (P= 0.0005). Quantitative analysis revealed that genotypes of -792G>A had effects on sperm concentration (P= 0.0025) and motility (P= 1.5 × 10(-7)). The G to A substitution was associated with decreased binding of the nuclear respiratory factor-1 (NRF-1) to the promoter region and decreased reporter gene activity. CONCLUSION: We have identified the core promoter of the human DAZL gene. We also provide preliminary evidence for the role of a novel SNP of the DAZL gene promoter in human spermatogenic failure.

Prospective assessment of fetal-maternal cell transfer in miscarriage and pregnancy termination.

BACKGROUND: Fetal cells (microchimerism) are acquired by women during pregnancy. Fetal microchimerism persists decades later and includes cells with pluripotent capacity. Persistent microchimerism has the capacity for both beneficial and detrimental maternal health consequences. Both miscarriage and termination of pregnancy can result in fetal microchimerism. We sought to determine whether cellular fetal microchimerism is acquired during management of pregnancy loss and further explored factors that could influence fetal cell transfer, including viability of fetal tissue, surgical versus medical management and gestational age. METHODS: Pregnant women (n= 150 samples from 75 women) with singleton pregnancies undergoing a TOP (n= 63) or treatment for embryonic or fetal demise (miscarriage, n= 12) were enrolled. Mononuclear cells were isolated from blood samples drawn before, and 30 min after, treatment. Fetal cellular microchimerism concentrations were determined using quantitative PCR for a Y chromosome-specific sequence, expressed as genome equivalents of fetal DNA per 100 000 maternal cell equivalents (gEq/10(5)). Detection rate ratios were determined according to clinical characteristics. RESULTS: Cellular fetal microchimerism was found more often in post- compared with pretreatment samples, 24 versus 5% (P= 0.004) and at higher concentrations, 0-36 versus 0-0.7 gEq/10(5) (P< 0.001). Likelihood of microchimerism was higher in surgical than medical management, detection rate ratio 24.7 (P= 0.02). The detection rate ratio for TOP versus miscarriage was 16.7 for known male fetuses (P= 0.02). Microchimerism did not vary with gestational age. CONCLUSIONS: Significant fetal cell transfer occurs during miscarriage and TOP. Exploratory analyses support relationships between obstetric clinical factors and acquisition of fetal cellular microchimerism; however, our limited sample size precludes definitive analysis of these relationships, and confirmation is needed. In addition, the long-term persistence and potential consequences of fetal microchimerism on maternal health merit further investigation.

Combining FISH with localisation microscopy: Super-resolution imaging of nuclear genome nanostructures.

The optical resolution of conventional far field fluorescence light microscopy is restricted to about 200 nm laterally and 600 nm axially and has been thought for many decades to be an insurmountable barrier for the quantitative spatial analysis of cellular and hence also nuclear constituents. Novel approaches in light microscopy have now overcome this barrier. Here, we report on a special method of localisation microscopy, spectral precision distance/position determination microscopy and its combination with fluorescence in situ hybridization to analyse the spatial distribution of specific DNA sequences in human cell nuclei at the macromolecular optical resolution level. As an example, repetitive DNA sequence DYZ2 located within the heterochromatin region on human chromosome Yq12 was labelled with clone pHY2.1. Between 300 and 700 single-probe molecules were resolved in individual chromatin domains, corresponding to a detected molecule density around 500/µm(2), i.e., many times higher than resolvable by conventional fluorescence microscopy. A mean localisation accuracy of about 20 nm indicated a mean optical resolution in the 50 nm range. Beyond new perspectives for light microscopic studies of specific chromatin nanostructures, this may open a new avenue towards the general analysis of copy number of specific DNA sequences in small regions of individual interphase nuclei.

A case of an infertile male with a small supernumerary marker chromosome negative for M-FISH and containing only heterochromatin.

AIM: To describe the case of a 32-year-old infertile male with small supernumerary marker chromosome (sSMCs) in 80% of peripheral lymphocytes. METHODS: G-banding, C-banding, STRP analysis, M-FISH and molecule diagnosis of Y-chromosomal microdeletions were performed to determine the origin of sSMCs. RESULTS: The karyotype of this patient was established as 47, XY, +mar/46, XY. C-banding showed that the marker chromosome was composed of heterochromatin without visible euchromatic material. No positive result was obtained in STRP, M-FISH and the microdeletion analysis of Y- chromosome. CONCLUSIONS: The small supernumerary marker chromosome could play a causative role in male infertility although the mechanism remains to be elucidated.

The prevalence of azoospermia factor microdeletion on the Y chromosome of Chinese infertile men detected by multi-analyte suspension array technology.

AIM: To develop a high-throughput multiplex, fast and simple assay to scan azoospermia factor (AZF) region microdeletions on the Y chromosome and establish the prevalence of Y chromosomal microdeletions in Chinese infertile males with azoospermia or oligozoospermia. METHODS: In total, 178 infertile patients with azoospermia (non-obstructed), 134 infertile patients with oligozoospermia as well as 40 fertile man controls were included in the present study. The samples were screened for AZF microdeletion using optimized multi-analyte suspension array (MASA) technology. RESULTS: Of the 312 patients, 36 (11.5%) were found to have deletions in the AZF region. The microdeletion frequency was 14% (25/178) in the azoospermia group and 8.2% (11/134) in the oligospermia group. Among 36 patients with microdeletions, 19 had deletions in the AZFc region, seven had deletions in AZFa and six had deletions in AZFb. In addition, four patients had both AZFb and AZFc deletions. No deletion in the AZF region was found in the 40 fertile controls. CONCLUSION: There is a high prevalence of Y chromosomal microdeletions in Chinese infertile males with azoospermia or oligozoospermia. The MASA technology, which has been established in the present study, provides a sensitive and high-throughput method for detecting the deletion of the Y chromosome. And the results suggest that genetic screening should be advised to infertile men before starting assisted reproductive treatments.

Screening for Y-chromosome microdeletions in infertile Indian males: utility of simplified multiplex PCR.

BACKGROUND & OBJECTIVE: Analysis of the microdeletions in the azoospermia factor (AZF) region of Y chromosome by PCR is an important screening tool in the work-up of infertile males opting for assisted reproductive techniques. In the present study, the Y chromosome microdeletions were analyzed by PCR using primers corresponding to 16 sequence tagged sites (STS) and three genes of the AZF region in infertile Indian men. Feasibility of developing a simplified multiplex PCR for screening of the Y chromosome microdeletions has been explored. METHODS: A total of 271 male subjects were analyzed, of which, 170 were infertile patients (51 oligospermic and 119 azoospermic) and 101 were fertile controls. Subjects showing normal karyotype only were included in the study. The semen analysis was done and plasma follicle stimulating hormone (FSH) concentrations were determined by radioimmunoassay. Testicular histopathology was analyzed by fine needle aspiration cytology (FNAC). RESULTS: Y chromosome microdeletions were observed in nine out of 170 (5.29%) infertile males all of whom were azoospermic. Of the nine subjects, two had deletions in AZFa, one in AZFb, three in AZFc and three in AZFb+c regions. No deletions were observed in the infertile severe oligospermic men (< 5 million sperm/ml semen) and fertile controls. No difference in the FSH concentrations of infertile patients with and without deletions (18.36 and 18.10 mIU/ml respectively) was observed. A clear relationship between Y chromosome microdeletions and testicular phenotypes could not be established. Two multiplex PCRs were designed using 7 STSs markers, which could detect Y chromosome microdeletions in infertile male subjects as efficiently as PCR based on larger number of PCR reactions. INTERPRETATION & CONCLUSION: The multiplex PCRs described in the present study may be a suitable, cost-effective and less time consuming method for screening the Y chromosome deletions in infertile males in routine clinical diagnosis and counselling prior to assisted reproduction.

Y chromosome microdeletions in Brazilian fertility clinic patients.

Microdeletions in Yq are associated with defects in spermatogenesis, while those in the AZF region are considered critical for germ cell development. We examined microdeletions in the Y chromosomes of patients attended at the Laboratory of Human Reproduction of the Clinical Hospital of the Federal University of Goiás as part of a screening of patients who plan to undergo assisted reproduction. Analysis was made of the AZF region of the Y chromosome in men who had altered spermograms to detect possible microdeletions in Yq. Twenty-three patients with azoospermia and 40 with severe oligozoospermia were analyzed by PCR for the detection of six sequence-tagged sites: sY84 and sY86 for AZFa, sY127 and sY134 for AZFb, and sY254 and sY255 for AZFc. Microdeletions were detected in 28 patients, including 10 azoospermics and 18 severe oligozoospermics. The patients with azoospermia had 43.4% of their microdeletions in the AZFa region, 8.6% in the AZFb region and 17.4% in the AZFc region. In the severe oligozoospermics, 40% were in the AZFa region, 5% in the AZFb region and 5% in the AZFc region. We conclude that microdeletions can be the cause of idiopathic male infertility, supporting conclusions from previous studies.

Y-chromosomal STR haplotype analysis reveals surname-associated strata in the East-German population.

In human populations, the correct historical interpretation of a genetic structure is often hampered by an almost inherent inability to differentiate between ancient and more recent influences upon extant gene pools. One method to trace recent population movements is the analysis of surnames, which, at least in Central Europe, can be thought of as traits 'linked' to the Y chromosome. Illegitimacy, extramarital birth and changes of surnames may have substantially obscured this linkage. In order to assess the actual extent of correlation between surnames and Y-chromosomal haplotypes in Central Europe, we typed Y-chromosomal short tandem repeat markers in 419 German males from Halle. These individuals were subdivided into three groups according to the origin of their respective surname, namely German (G), Slavic (S) or 'Mixed' (M). The distribution of the haplotypes was compared by Analysis of Molecular Variance. While the M group was indistinguishable from group G (PhiST=-0.0008, P>0.5), a highly significant difference (PhiST=0.0277, P<0.001) was observed between the S group and the combined G+M group. This surprisingly strong differentiation is comparable to that of European populations of much larger geographic and linguistic difference. In view of the major migration from Slavic countries into Germany in the 19th century, it appears likely that the observed concurrence of Slavic surnames and Y chromosomes is of a recent rather than an early origin. Our results suggest that surnames may provide a simple means to stratify, and thereby to render more efficient, Y-chromosomal analyses of Central Europeans that target more ancient events.

[Molecular anomalies of the Y chromosome: Consequences on male fertility]. / Polymorphismes du chromosome Y et fertilité masculine.

Molecular anomalies of the Y chromosome leading to male infertility are mainly microdeletions of the long arm of the Y chromosome. Three recurrently deleted portions of the long arm are the AZFa, AZFb and AZFc (AZF: Azoospermia Factor) regions. Complete deletions of the AZFc region are found in 10% of cases of severe male infertility. In addition to the AZF deletions, certain classes of Y chromosome (haplogroups) may also predispose to male infertility and could be transmitted to future male descents by various Assisted Reproductive Techniques (ART). Since the first discovery of microdeletions, the sequence of the Y chromosome has become available, revealing the mechanisms underlying deletion formation and also resulting in a coherent screening strategy. Recently, partial deletions of the AZF regions have been described. The significance of these deletions in the clinical context remains to be defined.

Ullrich-Turner Syndrome and Tumor Risk: Is There Another Chance to Early Gonadectomy in Positive TSPY and SRY Patients?

The presence of the Y chromosome in the karyotype of patients with disorders of sex differentiation is significantly associated with an increased risk to develop specific types of malignancies, predominantly type II germ cell tumors (GCTs). Gonadoblastoma in the gonads without an obvious testicular differentiation and intratubular germ cell neoplasia of unclassified type in testicular tissue are the precursor lesions of most GCTs. Gonadal dysgenesis, the characteristic feature of Ullrich-Turner syndrome (UTS), further contributes to increase this tumor risk. The reported incidence of Y chromosome material in UTS is 6 to 8% and in these cases an early gonadectomy is strongly recommended to prevent the risk of a malignancy. The aim of this work was to retrospectively analyze the clinical outcome and the histopathological and cytogenetic findings of our UTS patients who underwent gonadectomy to establish strict selection criteria aimed at promoting an organ-sparing surgery.

The longevity gender gap: are telomeres the explanation?

In this Perspective, we focus on the greater longevity of women as compared with men. We propose that, like aging itself, the longevity gender gap is exceedingly complex and argue that it may arise from sex-related hormonal differences and from somatic cell selection that favors cells more resistant to the ravages of time. We discuss the interplay of these factors with telomere biology and oxidative stress and suggest that an explanation for the longevity gender gap may arise from a better understanding of the differences in telomere dynamics between men and women.

Unique (Y;13) translocation in a male with oligozoospermia: cytogenetic and molecular studies.

The incidence of Y/autosome translocations is low. Whereas involvement of non-acrocentric chromosomes often leads to infertility, cases related with acrocentric chromosomes are usually familial with no or minimal effect on fertility. A de novo (Yp/13p) translocation was found in a 32-year-old male referred for severe oligozoospermia. Conventional cytogenetic procedures (GTG, CBG and NOR banding) and molecular cytogenetic techniques (Fluorescence In Situ Hybridization, FISH) were performed on high-resolution chromosomes obtained after peripheral blood lymphocyte culture as also on interphase nuclei of spermatogenic cells from semen samples. Screening of AZF microdeletions in the Yq11.2 region known to be involved with spermatogenesis defects was also performed. GTG banding showed a (Yp/13p) translocation in all scored metaphases. CBG and NOR staining of the derivative chromosome revealed the maintenance of Yq heterochromatin and of the 13p NOR region. FISH with centromeric Y and 13/21 probes, SRY specific probe and X/Y (p and q arms) sub-telomeric probes gave the expected number/location of fluorescent signals. Hybridisation with a pan-telomeric repeat (TTAGGG) probe showed an absence of the telomeric sequences at the fusion point of the rearranged chromosome. FISH analysis with probes to chromosomes X, Y, 13 and 18 showed an abnormal segregation of the translocated chromosome during meiosis I, which explains that only 13.6% of the secondary spermatocytes were normal. Most of these became arrested, as after meiosis II the large majority of the round spermatids were normal (70%), as were in consequence most of the sperm (85.1%). Multiplex-PCR confirmed the intactness of the SRY region and showed absence of AZF microdeletions. We report a novel de novo (Yp;13p) translocation characterised by loss of the 13p and Yp telomeres. Meiotic studies using FISH demonstrated meiosis I chromosome unpairing and mal segregation that justifies the severe oligozoospermia. Although most sperm have a normal chromosomal constitution, preimplantation genetic diagnosis should be considered an option for this patient.

Y chromosome microdeletions and alterations of spermatogenesis, patient approach and genetic counseling.

Infertility affects 15% of couples at reproductive age and human male infertility appears frequently idiopathic. The main genetic causes of spermatogenesis defect responsible for non-obstructive azoospermia and severe oligozoospermia are constitutional chromosomal abnormalities and microdeletions in the azoospermia factor region of the Y chromosome. The improvement of the Yq microdeletion screening method gave new insights in the mechanism responsible for the genesis of Yq microdeletions and for the consequences of the management of male infertility and genetic counselling in case of assisted reproductive technology.

Genetic causes of male infertility.

Male infertility, affecting around half of the couples with a problem to get pregnant, is a very heterogeneous condition. Part of patients are having a defect in spermatogenesis of which the underlying causes (including genetic ones) remain largely unknown. The only genetic tests routinely used in the diagnosis of male infertility are the analyses for the presence of Yq microdeletions and/or chromosomal abnormalities. Various other single gene or polygenic defects have been proposed to be involved in male fertility. Yet, their causative effect often remains to be proven. The recent evolution in the development of whole genome-based techniques may help in clarifying the role of genes and other genetic factors involved in spermatogenesis and spermatogenesis defects.

Anterior positioning of sex chromosomes on the head of human sperm sorted using visible wavelengths.

The human ejaculate contains subpopulations of sperm with distinct properties. Human X- and Y-bearing sperm were separated with fluorescence activated cell sorting. To avoid the use of UV light the quantitative DNA dyes DRAQ5® and Dyecycle™ Vybrant® Violet were used. Sorting efficiency was similar for both dyes, but lower than what is usually obtained with the classical method involving Hoechst 33342 and UV light (60-70% enrichment, versus 80-90%). A total of 2,739 spermatozoa were evaluated, from seven distinct samples using fluorescence in situ hybridization (FISH) chromosomal probes. No differences were found in sorted and unsorted populations in terms of chromosome positioning, and numeric chromosomal anomalies were not more evident following cell sorting. Furthermore in both sorted and unsorted populations the sex chromosomes were clearly located in the anterior portion of the sperm head, while a control autosome (chromosome 18) showed no such tendency, confirming previous findings. These results suggest that other quantitative DNA dyes may be used for sex chromosome-based human sperm sorting, but with lower efficiency than the standard UV-Hoechst based assay.