Improving preimplantation genetic diagnosis (PGD) reliability by selection of sperm donor with the most informative haplotype

BACKGROUND

The study is aimed to describe a novel strategy that increases the accuracy and reliability of PGD in patients using sperm donation by pre-selecting the donor whose haplotype does not overlap the carrier's one.

METHODS

A panel of 4-9 informative polymorphic markers, flanking the mutation in carriers of autosomal dominant/X-linked disorders, was tested in DNA of sperm donors before PGD. Whenever the lengths of donors' repeats overlapped those of the women, additional donors' DNA samples were analyzed. The donor that demonstrated the minimal overlapping with the patient was selected for IVF.

RESULTS

In 8 out of 17 carriers the markers of the initially chosen donors overlapped the patients' alleles and 2-8 additional sperm donors for each patient were haplotyped. The selection of additional sperm donors increased the number of informative markers and reduced misdiagnosis risk from 6.00% ± 7.48 to 0.48% ±0.68. The PGD results were confirmed and no misdiagnosis was detected.

CONCLUSIONS

Our study demonstrates that pre-selecting a sperm donor whose haplotype has minimal overlapping with the female's haplotype, is critical for reducing the misdiagnosis risk and ensuring a reliable PGD. This strategy may contribute to prevent the transmission of affected IVF-PGD embryos using a simple and economical procedure.

TRIAL REGISTRATION

All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. DNA testing of donors was approved by the institutional Helsinki committee (registration number 319-08TLV, 2008). The present study was approved by the institutional Helsinki committee (registration number 0385-13TLV, 2013).

A familial study of azoospermic men identifies three novel causative mutations in three new human azoospermia genes

PURPOSE

Up to 1% of all men experience azoospermia, a condition of complete absence of sperm in the semen. The mechanisms and genes involved in spermatogenesis are mainly studied in model organisms, and their relevance to humans is unclear because human genetic studies are very scarce. Our objective was to uncover novel human mutations and genes causing azoospermia due to testicular meiotic maturation arrest.

METHODS

Affected and unaffected siblings from three families were subjected to whole-exome or whole-genome sequencing, followed by comprehensive bioinformatics analyses to identify mutations suspected to cause azoospermia. These likely mutations were further screened in azoospermic and normozoospermic men and in men proven to be fertile, as well as in a reference database of local populations.

RESULTS

We identified three novel likely causative mutations of azoospermia in three genes: MEIOB, TEX14, and DNAH6. These genes are associated with different meiotic processes: meiotic crossovers, daughter cell abscission, and possibly rapid prophase movements.

CONCLUSION

The genes and pathways we identified are fundamental for delineating common causes of azoospermia originating in mutations affecting diverse meiotic processes and have great potential for accelerating approaches to diagnose, treat, and prevent infertility.Genet Med advance online publication 16 February 2017.

Distinctive pattern of expression of spermatogenic molecular markers in testes of azoospermic men with non-mosaic Klinefelter syndrome

PURPOSE

Mature sperm cells can be found in testicular specimens extracted from azoospermic men with non-mosaic Klinefelter syndrome (KS). The present study evaluates the expression of various known molecular markers of spermatogenesis in a population of men with KS and assesses the ability of those markers to predict spermatogenesis.

METHODS

Two groups of men with non-obstructive azoospermia who underwent testicular sperm-retrieval procedures were included in the study: 31 had non-mosaic KS (KS group) and 91 had normal karyotype (NK group). Each group was subdivided into mixed atrophy (containing some mature sperm cells) or Sertoli cell only syndrome according to testicular histology and cytology observations. Semi-quantitative histological morphometric analysis (interstitial hyperplasia and hyalinization, tubules with cells and abnormal thickness of the basement membrane) and expression of spermatogenetic markers (DAZ, RBM, BOLL, and CDY1) were evaluated and compared among those subgroups.

RESULTS

Clear differences in the histological morphometry and spermatogenetic marker expression were noted between the KS and NK groups. There was a significant difference in the expression of spermatogenetic markers between the subgroups of the NK group (as expected), while no difference could be discerned between the two subgroups in the KS group.

CONCLUSION

We conclude that molecular spermatogenetic markers have a pattern of expression in men with KS that is distinctively different from that of men with NK, and that it precludes and limits their use for predicting spermatogenesis in the former. It is suggested that this difference might be due to the specific highly abnormal histological morphometric parameters in KS specimens.

BRDT gene sequence in human testicular pathologies and the implication of its single nucleotide polymorphism (rs3088232) on fertility

Bromodomain testis-specific (BRDT) protein is essential for the normal process of spermatogenesis. Mutant mice that expressed truncated BRDT had impaired testicular histology with severely reduced sperm concentration and abnormal sperm morphology, while a model of knockout Brdt mice with no BRDT protein had complete meiotic arrest. A BRDT single nucleotide polymorphism (SNP) (rs3088232) was reported as being associated with infertility in men. We assessed testicular specimens of 276 azoospermic men who underwent testicular sperm extraction to search for specimens that showed spermatogenic impairments similar to those of mutant BRDT mice. Ten similar specimens were selected for BRDT gene sequencing and they revealed three NCBI-reported SNPs (rs10783071, rs3088232 and rs10747493) variously distributed among them. Bioinformatics analysis predicted that they would not affect protein activity. Further assessment of rs3088232 frequency in a large group of non-obstructive azoospermia men and fertile controls demonstrated no significant difference between them (27.2 and 21.7% respectively; p = 0.122, Fisher's exact test). We conclude that the testicular impairments observed in the 10 specimens were not a consequence of BRDT gene mutation. The association between BRDT rs3088232 and infertility that had been reported in other studies was not supported.

Preservation of sperm of cancer patients: extent of use and pregnancy outcome in a tertiary infertility center

Sperm cryopreservation is the best modality to ensure future fertility for males diagnosed with cancer. The extent to which cryopreserved sperm is actually used for impregnation, the fertility treatment options that are available and the success rates of these treatments have not been investigated in depth. The medical records of 682 patients who cryopreserved sperm cells due to cancer treatment were analyzed. Seventy of these patients withdrew their frozen sperm for fertility treatments over a 20-year period (most within the first 4 years after cryopreservation). Sperm quality of different malignancies and outcomes of assisted reproduction treatment (ART) for pregnancy achievement in relation to the type of treatment and the type of malignancy were evaluated. The results showed that the rate of using cryo-thawed sperm from cancer patients for fertility treatments in our unit was 10.3%. Sperm quality indices differed between different types of malignancies, with the poorest quality measured in testicular cancer. Conception was achieved in 46 of the 184 ART cycles (25%), and resulted in 36 deliveries. The use of intracytoplasmic sperm injection (ICSI) methodology yielded a significantly higher pregnancy rate (37.4%) than intrauterine insemination (IUI; 11.5%) and was similar to other groups of infertile couples using these modalities. In vitro fertilization (IVF) failed to produce pregnancies. In conclusion, the rate of use of cryopresseved sperm in cancer patients is relatively low (10.3%). Achievement of pregnancies by ICSI presents the best option but when there are enough stored sperm samples and adequate quality, IUI can be employed. Cryopreservation is nevertheless the best option to preserve future fertility potential and hope for cancer patients.

Sex Chromosome Alignment at Meiosis of Azoospermic Men With Azoospermia Factor Microdeletion

Deletions in the q arm of the Y chromosome result in spermatogenesis impairment. The aim of the present study was to observe the X and Y chromosome alignment in the spermatocytes of men with Y chromosome microdeletion of the azoospermia factor (AZF) region. This was performed by multicolor fluorescence in situ hybridization probes for the centromere and telomere regions. Testicular biopsies were performed in a testicular sperm extraction-intracytoplasmic sperm injection set-up in 11 azoospermic men: 8 (nonobstructive) with AZF deletions and 3 (obstructive) controls. Histological sections, cytology preparations of the testicular biopsies, and evaluation of the meiosis according to the percentage of XY and 18 bivalents formation were assessed. Spermatozoa were identified in at least one location in controls and specimens with AZFc-deleted Y chromosomes. Complete spermatocyte arrest was found in those with a deletion that included the entire AZFb region. Bivalent formation rate of chromosome 18 was high in all samples (81%-99%). In contrast, the rate of bivalent X-Y as determined by centromeric probes was lower but in the range favorable with spermatozoa findings in controls and patients with the AZFc deletion (56%-90%), but not in those with AZFb-c deletions (28%-29%). A dramatic impairment in the normal alignment of X and Y telomeres in the specimen with AZFb-c deletion was shown (29%), compared to the specimens with AZFc deletion (70%-94%). It is suggested that the absence of sperm cells in specimens with the entire AZFb and with AZFb-c deletions is accompanied by meiosis impairment, perhaps as a result of the extent of the deletion or because of the absence of genes that are involved in the X and Y chromosome alignment.

Screening for partial AZFa microdeletions in the Y chromosome of infertile men: is it of clinical relevance?

OBJECTIVE

To evaluate the frequency of complete and partial AZFa Y-chromosome microdeletions among infertile Israeli men. To review the published frequencies and histologic findings of AZFa deletions.

DESIGN

Retrospective study.

SETTING

Academic medical center.

PATIENT(S)

A total of 1,260 infertile Israeli men. Literature review (2000-2010) of reports on men with AZFa deletions and their testicular findings.

INTERVENTION(S)

The DNA of 1,260 infertile men was evaluated for AZF microdeletions. The DNA of 657 of them with undetected microdeletions was analyzed for partial AZFa deletion in the USP9Y and DDX3Y genes using sequence-tagged sites beyond EAA/EMQN recommendations.

MAIN OUTCOME MEASURE(S)

The frequency of complete and partial AZFa microdeletions. Availability of sperm cells for intracytoplasmic sperm injection in men with complete/partial microdeletions.

RESULT(S)

Two men had complete AZFa deletion (a frequency of 0.28% among nonobstructive azoospermic men). None had partial AZFa deletions.

CONCLUSION(S)

The likelihood of finding sperm cells in men with complete AZFa deletions is negligible. Complete AZFa deletion is rare and usually associated with azoospermia and absence of sperm cells in testicular tissue. The low frequency of partial AZFa deletions and the inconsistent prospects for spermatogenesis reported in the literature question the need for routine assessment of microdeletions in genes, such as USP9Y or DDX3Y.

Involvement of the prostate and testis expression (PATE)-like proteins in sperm-oocyte interaction

BACKGROUND

The prostate and testis expression (PATE)-like family of proteins are expressed mainly in the male genital tract. They are localized in the sperm head and are homologous to SP-10, the acrosomal vesicle protein also named ACRV1. Our aim was to characterize the expression and functional role of three PATE-like proteins in the testis and ejaculated sperm.

METHODS

The expression and localization of PATE-like proteins in human testis biopsies (n= 95) and sperm cells were assessed by RT-PCR, immunohistochemistry and immunofluorescence staining (at least 600 sperm cells per specimen). The function of the PATE protein was tested by the hemizona assay and hamster egg penetration test (HEPT).

RESULTS

PATE and PATE-M genes and proteins were present almost exclusively in germ cells in the testis: immunoflourescence showed that the percentage of germ cells positive for PATE, PATE-M and PATE-B was 85, 50 and 2%, respectively. PATE and PATE-M proteins were localized in the equatorial segment of the sperm head, while PATE-B protein was localized in the post-acrosomal region. A polyclonal antibody (Ab, at 1:50 and 1:200 dilutions) against the PATE protein did not inhibit sperm-zona binding in the hemizona assay (hemizona index of 89.6 ± 10 and 87 ± 36%, respectively). However, there was inhibition of sperm-oolemma fusion and penetration in the HEPT (penetration index: without Ab 7 ± 3.9; Ab dilution of 1:100, 4 ± 3.5; Ab dilution of 1:20, 0.6 ± 1.2, P < 0.001).

CONCLUSIONS

Our data suggest that PATE protein is involved in sperm-oolemma fusion and penetration but not sperm-zona binding.

The likelihood of finding mature sperm cells in men with AZFb or AZFb-c deletions: six new cases and a review of the literature (1994-2010)

OBJECTIVE

To reassess the predictive value of detecting sperm cells in men with AZFb or AZFb-c deletions.

DESIGN

Retrospective analysis of previously reported men with AZFb or AZFb-c deletions and the addition of six new cases.

SETTING

Fertility institution.

PATIENT(S)

Men with both sequence tagged site marker identification and testicular cytology/histology findings.

INTERVENTION(S)

Systematic review of reported men with microdeletions that included eligibility, data extraction and analysis.

MAIN OUTCOME MEASURE(S)

Availability of sperm cells for intracytoplasmic sperm injection (ICSI) in men with AZFb/AZFb-c microdeletions.

RESULT(S)

The average prevalences reported for AZFb, AZFb-c, partial AZFb, and partial AZFb-c in azoospermic men were 0.9%±0.07%, 2.7%±0.93%, 1.23%±0.9%, and 1%±0.6%, respectively. Sperm cells were identified in 7% and 3% of the 28 and 71 men with complete AZFb and AZFb-c and in 57% and 43% of the 14 and 7 men with partial AZFb and AZFb-c deletions, respectively. The likelihood of finding sperm cells in men with complete versus partial AZFb and AZFb-c deletions was significantly lower. As yet, no clinical or chemical pregnancy after ICSI in cases with complete AZFb/b-c microdeletions has been reported.

CONCLUSION(S)

Determining the extent of AZFb or AZFb-c deletions is critical considering the frequency and the reasonable prospect of finding sperm cells in partial AZFb/AZFb-c deletions. Referring men with complete AZFb/b-c microdeletions to testicular sperm extraction/ICSI programs should be revaluated.

Virtual azoospermia and cryptozoospermia--fresh/frozen testicular or ejaculate sperm for better IVF outcome?

Men diagnosed as having azoospermia occasionally have a few mature sperm cells in other ejaculates. Other men may have constant, yet very low quality and quantity of sperm cells in their ejaculates, resulting in poor intracytoplasmic sperm injection (ICSI) outcome. It has not been conclusively established which source of sperm cells is preferable for ICSI when both ejaculate and testicular (fresh or frozen) sperm cells are available. It is also unclear whether there is any advantage of fresh over frozen sperm if testicular sperm is to be used. We used ejaculate, testicular (fresh or frozen) sperm cells, or both for ICSI in 13 couples. Five of these couples initially underwent ICSI by testicular sperm extraction, because the males had total azoospermia, and in later cycles with ejaculate sperm cells. Ejaculate sperm cells were initially used for ICSI in the other 8 patients, and later with testicular sperm cells. The fertilization rate was significantly higher when fresh or frozen-thawed testicular sperm cells were used than when ejaculated sperm cells were used. Likewise, the quality of the embryos from testicular (fresh and frozen) sperm was higher than from ejaculated sperm (65.3% vs 53.2%, respectively, P < .05). The use of fresh testicular sperm yielded better implantation rates than both frozen testicular sperm and ejaculate. Therefore, fresh testicular sperm should be considered first for ICSI in patients with virtual azoospermia or cryptozoospermia because of their superior fertility.

Long-term cryostorage of sperm in a human sperm bank does not damage progressive motility concentration

BACKGROUND

The use of quarantined cryopreserved semen is mandatory in donor insemination programs. Whether sperm cells can survive and retain their ability to fertilize after long-term storage remains a controversial issue. The objective of this study was to determine the effect of the duration of cryostorage in liquid nitrogen on the sperm cells' progressive motility concentration (PMC) in a large study group.

METHODS

A total of 2525 thawed sperm specimens, packed in straws and donated by 72 sperm bank donors for intrauterine insemination (IUI), were evaluated in an assisted reproduction institute. PMC was recorded after 0.5-14.4 years of cryostorage.

RESULTS

The mean (+/-SD) value of PMC of all study samples was 10.8 +/- 3.3 x 10(6)/ml after freezing/thawing and before cryostorage (T0), and 12.3 +/- 2.9 x 10(6)/ml after storage and before using the specimen for IUI (T1, P < 0.0001). Specimen storage for different lengths of time revealed that storage duration had no significant influence on the PMC of the specimens (r = -0.03, P = 0.08). The PMC of partially filled straws was lower than in full straws. Cryostorage duration made no difference in the PMC of raw and washed sperm specimens.

CONCLUSION

Prolonged storage of donated sperm in liquid nitrogen had no influence on the PMC of the specimens and therefore should not alter the fertilization potency of donated sperm. The high post-storage values of the PMC compared with the pre-storage PMC values was probably an artifact of the small volume of the pre-storage sample.

Cryptorchidism: incidence and sperm quality in infertile men

In a population of 8500 men attending the andrology outpatient clinic, 200 men (2.35%) were recorded as having some disturbances with the descent of the testes into the scrotum. Medical history of the patients revealed that 51 underwent unilateral orchidopexy; 40 bilateral orchidopexy; and 24 were treated with human chorionic gonadotropin in order to induce descent of their testes. In addition, 6 patients reported spontaneous descent of the testes, and 13 others were found to be unilaterally cryptorchid upon physical examination. Results of semen analysis, hormonal profile, testes position, and testicular volume were compared to those of 105 proven fertile men. The major finding of this study shows that post-partum undescended testes suffer from primary Sertoli cell malfunction as reflected by elevated serum follicle stimulating hormone levels. Serum luteinizing hormone and testosterone levels were within the normal range. Surgical descent of the testes did not improve sperm production, proved by low sperm quality of all the study groups, compared to the cryptorchid group. Among the patients who were operated on, no correlation was found between age at operation and semen variables. All groups showed poor sperm quality which can be defined as oligoteratoasthenozoospermia. The degree of spermatogenic damage was in the following order of diagnosis or treatment: bilateral orchidopexy greater than cryptorchid testes greater than hormonal treatment greater than unilateral orchidopexy greater than late spontaneous descent of the testes. Thus, it is advisable to postpone surgical treatment of cryptorchidism and apply this only after a waiting period, and if the hormonal approach has failed to descend the testis.

USP26 gene variations in fertile and infertile men

BACKGROUND

The human X chromosome is enriched with testis-specific genes that may be crucial for male fertility. One is the ubiquitin-specific protease 26 (USP26). Five frequent mutations have been identified: 1737G>A, 1090C > T, 370-371insACA, 494T > C and 1423C>T (with the latter three usually detected in a cluster). Their role in infertility is still controversial. This study assesses the association of the most frequent USP26 mutations with male infertility and male infertility etiology factors.

METHODS

The study included 300 infertile and 287 fertile men. Data were collected on ethnicity (according to maternal origin) and family history of reproduction. Clinical records from 235 infertile and 62 fertile (sperm bank donors) men were available and summarized. The five mutations were investigated by bioinformatic tools and their frequencies were assessed by restriction analysis. The results were correlated with clinical findings. Segregation of the mutations in four families was analyzed.

RESULTS

The five analyzed mutations were detected in 44 men from both fertile and infertile groups. The cluster and the 1090C>T mutations showed the highest frequency among Arabs and Sephardic Jews of the infertile group, respectively. Inheritance studies showed that mutations were not always associated with the infertility trait. Mutations 1090C>T and 1737G>A were significantly associated with a history of inguinal hernia (P = 0.007 and P = 0.043, respectively). The prevalence of inguinal hernia among men with the 1090C > T mutation was 33.3% (5/15 men), higher than that reported in infertile men (6.7%).

CONCLUSIONS

Mutation 1090C > T may be a new genetic risk factor for developing inguinal hernia which may be associated with impaired male fertility.

Acetylcholinesterase-R increases germ cell apoptosis but enhances sperm motility

Changes in protein subdomains through alternative splicing often modify protein-protein interactions, altering biological processes. A relevant example is that of the stress-induced up-regulation of the acetylcholinesterase (AChE-R) splice variant, a common response in various tissues. In germ cells of male transgenic TgR mice, AChE-R excess associates with reduced sperm differentiation and sperm counts. To explore the mechanism(s) by which AChE-R up-regulation affects spermatogenesis, we identified AChE-R's protein partners through a yeast two-hybrid screen. In meiotic spermatocytes from TgR mice, we detected AChE-R interaction with the scaffold protein RACK1 and elevated apoptosis. This correlated with reduced scavenging by RACK1 of the pro-apoptotic TAp73, an outcome compatible with the increased apoptosis. In contrast, at later stages in sperm development, AChE-R's interaction with the glycolytic enzyme enolase-α elevates enolase activity. In transfected cells, enforced AChE-R excess increased glucose uptake and adenosine tri-phosphate (ATP) levels. Correspondingly, TgR sperm cells display elevated ATP levels, mitochondrial hyperactivity and increased motility. In human donors' sperm, we found direct association of sperm motility with AChE-R expression. Interchanging interactions with RACK1 and enolase-α may hence enable AChE-R to affect both sperm differentiation and function by participating in independent cellular pathways.

Histone H4 acetylation and AZFc involvement in germ cells of specimens of impaired spermatogenesis

OBJECTIVE

To measure histone-H4 acetylation and involvement of the AZFc region in testicular mixed atrophy.

DESIGN

Prospective study.

SETTING

University-affiliated medical center.

PATIENT(S)

Azoospermic men (n = 23) who underwent testicular sperm extraction and preparation for intracytoplasmic sperm injection (ICSI) divided into obstructive azoospermia with complete spermatogenesis (group A), testicular mixed atrophy (group B), and testicular mixed atrophy associated with AZFc deletion (group C).

INTERVENTION(S)

Testicular biopsy evaluation by Western blotting and quantitative immunohistochemistry of histone-H4 hyperacetylation (Hypac-H4) and lysine-12 acetylation (Lys12ac-H4).

MAIN OUTCOME MEASURE(S)

Percentage of spermatogonia and spermatids stained by Hypac-H4 and Lys12ac-H4 antibodies in retrieved specimens.

RESULT(S)

The percentage of spermatogonia stained for Hypac-H4 and Lys12ac-H4 in groups B and C was statistically significantly reduced. The percentage of elongated spermatids showing positive staining to Hypac-H4 was statistically significantly lower in group B than group A. The percentage of Lys12ac-H4-labeled spermatids was similar for all groups. Hypac-H4 and Lys12ac-H4 processes were highly correlated in spermatogonia but not in spermatids.

CONCLUSION(S)

The reduced percentage of spermatogonia with Hypac-H4 and Lys12ac-H4 in groups B and C may contribute to lower sperm production in mixed atrophy. Spermatids Hypac-H4 impairment in mixed atrophy did not deteriorate further by AZFc region deletion.

Deoxyribonucleic acid-damaged sperm in cryopreserved-thawed specimens from cancer patients and healthy men

A similarity was found between the percentage of thawed, DNA-damaged spermatozoa in cancer patients and that in candidates to become sperm bank donors who had low sperm cryofreezability. Both groups were significantly different from the sperm bank donor group. It is suggested that the higher rate of DNA fragmentation in sperm from cancer patients compared with sperm bank donors is apparently a result of selecting donors by the level of sperm cryofreezability (i.e., high), rather than a direct effect of an existing malignancy.

Role of poly(ADP-ribosyl)ation during human spermatogenesis

OBJECTIVE

Genomic stability of cells is known to be linked to their poly(ADP-ribosyl)ation capacity. We aimed to demonstrate, for the first time, the patterns of poly(ADP-ribosyl)ation during human spermatogenesis.

DESIGN

Retrospective case-control study.

SETTING

Teaching hospital.

PATIENT(S)

Azoospermic men who underwent testicular biopsy for sperm recovery.

INTERVENTION(S)

Testicular biopsy evaluation by immunohistochemistry for the expression of poly(ADP-ribose) polymerase-1 (PARP-1) enzyme and of poly(ADP-ribose) (PAR) (an indicator for PARP activity.)

MAIN OUTCOME MEASURE(S)

The subcellular localization of both markers in testes with full spermatogenesis (obstructive azoospermia), spermatocyte maturation arrest, or Sertoli cell-only syndrome.

RESULT(S)

Expression of both markers was localized in germ cell nuclei in full spermatogenesis: PAR expression, indicating PARP activity, was exhibited in round and elongating spermatids and in a subpopulation of primary spermatocytes. Strong immunoreactivity for PAR was identified in all of the spermatocytes in maturation arrest at the spermatocyte level. Sertoli cells lacked immunoreactivity for both markers, whereas other somatic testicular cells were rarely immunostained.

CONCLUSION(S)

The detection of PAR expression in germ-line cells and its subcellular localization in meiotic and postmeiotic prophases demonstrates chromatin modifications occurring during spermatogenesis and establishes a key role for poly(ADP-ribosyl)ation in germ cell differentiation, presumably to safeguard DNA integrity.

Is a genetic defect in Fkbp6 a common cause of azoospermia in humans?

FK506-binding protein 6 (Fkbp6) is a member of a gene family containing a prolyl isomerase/FK506-binding domain and tetratricopeptide protein-protein interaction domains. Recently, the targeted inactivation of Fkbp6 in mice has been observed to result in aspermic males and the absence of normal pachytene spermatocytes. The loss of Fkbp6 results in abnormal pairing and a misalignment of the homologous chromosomes, and in non-homologous partner switches and autosynapsis of the X chromosome cores in meiotic spermatocytes. In this study, we analyzed whether human FKBP6 gene defects might be associated with human azoospermia. We performed a mutation analysis in all the coding regions of the human FKBP6 gene in 19 patients with azoospermia resulting from meiotic arrest. The expression of the human FKBP6 gene was specific to the testis, and a novel polymorphism site, 245C --> G (Y60X) could be found in exon 3. Our findings suggest that the human FKBP6 gene might be imprinted in the testis based on an analysis using two polymorphism sites.

Expression profile of AZF genes in testicular biopsies of azoospermic men

BACKGROUND

The Y-chromosome AZF regions include genes whose functions and specific roles in spermatogenesis have not been fully clarified. This study investigated the expression of several AZF (USP9Y, DDX3Y/DDX3Yt1, EIF1AY and PRY) and USP9X transcripts in testicular biopsies of 89 azoospermic men who had been classified by histology and cytology assessments.

METHODS

Expression was analysed by RT-PCR, and some biopsies were evaluated by multiplex RT-PCR. Quantitative PCR was performed in some biopsies to determine the ratio of the testis-specific transcript DDX3Yt1 to the total DDX3Y transcription.

RESULTS

The expression of USP9Y, USP9X and DDX3Y was found in all the specimens tested, whereas DDX3Yt1 expression was diminished or undetectable in several biopsies with impaired spermatogenesis. EIF1AY was detected in all except two of the specimens. Noteworthy, PRY expression was detected mainly in biopsies with germ cells, and this association was significant (P < 0.001). An identical expression profile was obtained by either single or multiplex RT-PCR.

CONCLUSIONS

These findings suggest that PRY is usually expressed in germ cells, whereas the other transcripts are also expressed in testicular somatic cells. The absence of EIF1AY expression might sporadically contribute to azoospermia. The decreased ratio of DDX3Yt1/DDX3Y transcript in impaired spermatogenesis suggests that the DDX3Yt1 transcript is under-expressed in impaired spermatogenesis. The findings contribute to the search and selection of the most valuable gene markers potentially useful as additional tools for predicting complete spermatogenesis by multiplex expression analysis.

Use of sex chromosome bivalent pairing in spermatocytes of nonobstructive azoospermic men for the prediction of successful sperm retrieval

OBJECTIVE

To find the most informative method of XY bivalent detection for spermatozoa presence in testicular tissue of nonobstructive azoospermic men.

DESIGN

Prospective study.

SETTING

Institute for the Study of Fertility, affiliated with a university medical faculty.

PATIENT(S)

Thirty-five men with azoospermia, divided into subgroups: complete maturation arrest (n = 10), mixed atrophy (n = 14), and obstructive azoospermia (n = 11).

INTERVENTION(S)

Testicular tissue biopsies for sperm extraction.

MAIN OUTCOME MEASURE(S)

Histopathologic and cytology analyses and the presence of XY bivalent formation by fluorescence in situ hybridization probes for centromere and subtelomere regions. Immunostaining of gamma-H2AX for sex body (SB) identification was also performed.

RESULT(S)

Percentage of spermatocytes with X-Y pairing, determined by the paired short arms pseudoautosomal region, was significantly higher than percentage of spermatocytes with long arm telomeres in proximity in all three groups. The parameter of q telomeres in proximity was the most sensitive index to distinguish one group from the other. Stained SB by gamma-H2AX was found to be the most informative for the prediction of successful sperm retrieval.

CONCLUSION(S)

Alignment of the X and Y axes that occurs in the late zygotene stage probably precedes the stage in which the SB is stained by gamma-H2AX. Consequently, because of the nonhomogeneity of the testis, when histology raises suspicion of complete maturation arrest percentage of spermatocytes with stained SB is the most informative parameter for sperm presence on sperm retrieval.

Polymorphic alleles of the human MEI1 gene are associated with human azoospermia by meiotic arrest

Genetic mechanisms are implicated as a cause of some male infertility, yet are poorly understood. Mouse meiotic mutant mei1 (meiosis defective 1) was isolated by a screening of infertile mice. Male mei1 mice have azoospermia due to meiotic arrest, and the mouse Mei1 gene is responsible for the mei1 phenotype. To investigate whether human MEI1 gene defects are associated with azoospermia by meiotic arrest, we isolated the human MEI1 cDNA based on the mouse Mei1 amino acid sequence. MEI1 is expressed specifically in the testis. Mutational analysis by direct sequencing of all MEI1 coding regions was performed in 27 men (13 European Americans, 13 Israeli and 1 Japanese) having azoospermia due to complete early meiotic arrest. This identified four novel, coding single-nucleotide-polymorphisms (cSNPs), i.e., SNP1 (T909G), SNP2 (A1582G), SNP3 (C1791A) and SNP4 (C2397T) in exons 4, 8, 9 and 14, respectively. Using these cSNPs, an association study was carried out between 26 non-Japanese patients with azoospermia and two sets of normal control men (61 normal European Americans and 60 Israelis). Consequently, SNP3 and SNP4 were shown to be associated with azoospermia among European Americans (P =0.0289 and P =0.0299 for genotype and allele frequencies at both the polymorphic sites, respectively), although no such association was observed among Israelis (P >0.05). Haplotype estimation revealed that the frequencies of SNP3-SNP4 (C-T), SNP3-SNP4 (A-C) and SNP3-SNP4 (A-T) were higher in the European American patients, and the frequency of SNP3-SNP4 (A-T) was also higher than in both control groups. These results suggest that MEI1 may play a role in meiosis during spermatogenesis, especially in European Americans.

Comparison of Efficacy of Two Techniques for Testicular Sperm Retrieval in Nonobstructive Azoospermia: Multifocal Testicular Sperm Extraction Versus Multifocal Testicular Sperm Aspiration

To compare the efficacy of 2 sperm-retrieval procedures, testicular sperm extraction (TESE) and testicular sperm aspiration (TESA), during the same procedure using the same subjects as their own controls. The presence of mature testicular sperm cells and motility were evaluated in 87 men with nonobstructive azoospermia (NOA) by means of multifocal TESE and multifocal TESA, which were performed during the same procedure using the same subjects as their own controls. Sperm cells were recovered by TESE in 54 cases, but by TESA in only 36 cases. There were significantly more cases (n = 20) in which sperm cells were recovered by TESE only, compared with 2 cases in whom cells were recovered by TESA only (McNemar's test, P < .001). The mean number of locations in each testis in which sperm cells were detected was significantly higher in the TESE group. In significantly more cases (n = 27), motility was observed in TESE material only, compared with 3 cases in which motility was present in material extracted by TESA only (McNemar's test, P < .001). Mean number of locations in each testis with motile sperm cells was significantly higher in the TESE group. The TESE procedure yielded significantly more sperm cells, as was also reflected by the difference in number of straws with cryopreserved sperm. This comparative prospective clinical study revealed that multifocal TESE is more efficient than multifocal TESA for sperm detection and recovery in men with NOA and should be the procedure of choice for sperm retrieval for them.

Severe hypospermatogenesis in cases of nonobstructive azoospermia: should we use fresh or frozen testicular spermatozoa?

The aim of this comparative clinical study was to examine whether the fertilizing potential of frozen-thawed testicular sperm in the most severe cases of hypospermatogenesis is reduced compared with fresh testicular sperm. The results could determine the necessity of using fresh testicular sperm cells, which mandates involving the spouse by performing simultaneous in vitro fertilization intracytoplasmic sperm injection (IVF-ICSI) treatment in this subgroup of nonobstructive azoospermia (NOA) patients. We studied 13 couples in which the husband was diagnosed as having NOA and few motile testicular sperm cells or only immotile testicular sperm cells were isolated by testicular sperm extraction (TESE). Each couple underwent both an ICSI cycle, in which fresh testicular sperm that were retrieved shortly beforehand were injected, and a consecutive cycle, which used frozen-thawed sperm that were retrieved in the original TESE procedure but were cryopreserved and stored until use. We found that motility was lost during the freezing and thawing process in some cases, which resulted in significantly more cycles with only immotile sperm cells for injection in the frozen-thawed sperm group (38.5%) than in the fresh sperm group (7.7%; P < .05). Availability of only immotile sperm cells significantly reduced fertilization rates in both fresh and frozen-thawed groups, but the respective overall fertilization rate (44.9% vs 41.1%) and quality of embryos and pregnancy rate (18.2% vs 15.4%) were not significantly different between groups. Implantation rates were more favorable in the fresh sperm group (10.5% vs 5.9%), but not significantly so. We conclude that, although cryopreservation does impair motility, which results in significantly more cycles with only immotile sperm cells for ICSI in the most severe forms of hypospermatogenesis, fertilization and pregnancy rates are not significantly compromised.

Detection of calretinin expression in abnormal immature Sertoli cells in non-obstructive azoospermia

The current study identified for the first time calretinin expression in abnormal Sertoli cells of azoospermic men who underwent testicular biopsy for sperm recovery and application of the retrieved sperm by in vitro fertilization techniques. Testicular biopsies with various spermatogenic impairments were evaluated immunohistochemically for the expression of the calretinin calcium-binding protein and the marker for immaturity of Sertoli cells, cytokeratin-18 (CK-18). Distribution of the markers was assessed in testes demonstrating a histological phenotype of mixed atrophy, Sertoli cell-only, or normal spermatogenesis (obstructive-azoospermia) and in men carrying a deletion in the azoospermia factor region located on the Y chromosome. Calretinin-immunopositive immature Sertoli cells revealed by co-localization of both markers, calretinin and CK-18, were identified in the mixed atrophy group in seminiferous tubules demonstrating spermatogenic failure. Sertoli cells expressing both markers were rarely detected in all other groups. Leydig cells in all the assessed biopsies expressed calretinin and served as a built-in control for immunoreactivity. This pattern of calretinin-selective expression in immature Sertoli cells suggests a functional relationship between calretinin expression and the degree of Sertoli cell differentiation. Disorders of Sertoli cell differentiation as indicated by calretinin and/or CK-18 expression contribute to the multifactorial mechanisms underlying spermatogenic failure.

Differentiating between primary and secondary Sertoli-cell-only syndrome by histologic and hormonal parameters

The contribution of histologic differentiation between primary and secondary Sertoli-cell-only (SCO) syndrome in azoospermic men was evaluated. No correlation was found between the presence of sperm cells in the testis and the histologic findings or inhibin B or FSH levels, suggesting a low prognostic value for this differentiation.

Sertoli cell inactivation by cytotoxic damage to the human testis after cancer chemotherapy

OBJECTIVE

To assess Sertoli cell involvement in postchemotherapy azoospermia.

DESIGN

Case report.

SETTING

Teaching hospital.

PATIENT(S)

A 31-year-old azoospermic man who underwent cancer cytotoxic chemotherapy for non-Hodgkin's lymphoma at 13 years of age.

INTERVENTION(S)

Testicular biopsy specimens were obtained for sperm recovery in preparation for intracytoplasmic sperm injection. The biopsy specimens were evaluated by quantitative immunohistochemistry for the immature Sertoli cell markers cytokeratin 18 (CK-18) and D2-40.

MAIN OUTCOME MEASURE(S)

Extent of immature Sertoli cells.

RESULT(S)

A fraction of Sertoli cells (13%) in the atrophic tubules of this patient reexpressed the intermediate filament protein CK-18, which is normally absent after puberty, but not the D2-40 antigen, an Mr 40,000 a-linked membrane glycoprotein, whose loss of expression at puberty marks an irreversible step in Sertoli cell maturation. Tubules with normal spermatogenic progression lined by Sertoli cells negative for CK-18 were also observed.

CONCLUSION(S)

A fraction of Sertoli cells of this patient initially progressed to full maturation at puberty and reverted to a dedifferentiated state marked by reexpression of CK-18 as a consequence of chemotherapy. This inactivation of Sertoli cells caused by the cytotoxicity of the chemotherapeutic drugs may have contributed to the spermatogenic impairment and resulting infertility.

Seasonal variations in pre- and post-thaw donor sperm quality

BACKGROUND

The present study was conducted to evaluate seasonal variability in the quality of pre- and post-thaw semen parameters among sperm bank donors.

METHODS

The first two consecutive ejaculates during the months March (spring, 92 males), June (summer, 97 males), September (autumn, 81 males) and December (winter, 97 males) were analysed. A comparison was made between sperm parameters from the same sperm donor at different seasons. Only males who donated semen samples during at least two seasons were enrolled in the study group (n = 103). Sperm specimens were cryopreserved in aliquots with fixed range of 8-12 x 10(6)/ml of progressive motile sperm concentration after thawing.

RESULTS

Differences between months were found in sperm concentration (P = 0.030) and normal morphology (P = 0.038); highest values were found in March and December, and the lowest in September. Mean specimen volume and percent of motile sperm cells did not vary throughout the seasons. The freezability of the donors' sperm dropped dramatically from March to September, as determined by the number of straws (fixed aliquots of 0.5 ml) and total thawed progressive motile sperm that were cryopreserved for each male (P = 0.017 and P = 0.002, respectively).

CONCLUSIONS

Cryopreservation of donor sperm is more effective during winter and spring than during the rest of the year.

Spermatogonial proliferation patterns in men with azoospermia of different etiologies

OBJECTIVE

To demonstrate the pattern(s) of spermatogonial proliferation in different spermatogenic disorders.

DESIGN

Retrospective case-control study. Teaching hospital.

PATIENT(S)

Azoospermic men who underwent testicular biopsy for sperm recovery and preparation for intracytoplasmic sperm injection.

INTERVENTION(S)

Testicular biopsy evaluation by quantitative immunohistochemistry for proliferating cell nuclear antigen (PCNA).

MAIN OUTCOME MEASURE(S)

The expression of PCNA in spermatogonia as an index of proliferating activity in testes with focal spermatogenesis, spermatocyte maturation arrest, or normal spermatogenesis.

RESULT(S)

In biopsies with focal spermatogenesis (11 men), there was a statistically significant reduction of PCNA-labeled spermatogonia in seminiferous tubules showing spermatocyte arrest compared with the expression in adjacent tubules with advanced spermatogenic stage or in normal spermatogenesis (obstructive azoospermia, six men). However, PCNA expression in tubules of the group with complete maturation arrest (six men) was significantly higher compared with the same spermatogenic defect-spermatocyte arrest-within focal spermatogenesis biopsies.

CONCLUSION(S)

Different causes underlie the spermatogenic disorders reported in this study. In focal spermatogenesis, the disorder is associated with the presence of mitotic inactive spermatogonia. The detection of normal active spermatogonia in the spermatocyte arrest group indicates that the spermatogenic defect, which is accompanied by meiosis impairment, is not related to a malfunction of spermatogonial proliferation.

Azoospermia in patients heterozygous for a mutation in SYCP3

BACKGROUND

Many cases of male infertility are diagnosed as idiopathic, reflecting poor understanding of the molecular defects underlying the abnormality. As more gene mutations causing male infertility in mice become known, there are improving prospects that knowledge about the genetic aetiology of human male infertility can be expanded. Sycp3 encodes a component of the synaptonemal complex. A null mutation of Sycp3 in mice causes azoospermia with meiotic arrest. We tested the hypothesis that mutation of the human testis-specific SYCP3 is associated with human non-obstructive azoospermia.

METHODS

Human SYCP3 was isolated on the basis of homology between mouse Sycp3 cDNA and human genome sequences at the aminoacid level. Tissue-specific expression of SYCP3 was analysed by PCR of human cDNA. Samples of DNA from 19 azoospermic patients with maturation arrest and 75 normal fertile control men were screened for mutations in the SYCP3 gene by sequence analysis of the gene. The functional significance of the mutations found was analysed by a protein interaction study of the wild-type and truncated SYCP3 proteins.

FINDINGS

We identified in two patients a 1 bp deletion (643delA) that results in a premature stop codon and truncation of the C-terminal, coiled-coil-forming region of the SYCP3 protein. The mutant protein showed greatly reduced interaction with the wild-type protein in vitro and interfered with SYCP3 fibre formation in cultured cells.

INTERPRETATION

We suggest that SYCP3 has an essential meiotic function in human spermatogenesis that is compromised by the mutant protein via dominant negative interference.

Members of the CDY family have different expression patterns: CDY1 transcripts have the best correlation with complete spermatogenesis

The CDY family of genes is of special interest because some of them are included in chromosome-Y microdeletions detected among infertile men and are apparently involved in the spermiogenetic process. In this study, we employed the reverse transcriptase/polymerase chain reaction technique to test the RNA expression of the various transcripts of these genes in testicular biopsies of 84 azoospermic men who had been classified by comprehensive histology and cytology analyses. We also evaluated the feasibility of detecting CDY expression in biopsies taken by testicular sperm extraction versus acquisition by aspiration. There was a significant association between the type of testicular impairment and the expression of CDY1 and CDY2 transcripts. CDY2 was expressed whenever germ cells were present, but CDY1 major and especially CDY1 minor and short transcripts were identified almost exclusively when mature spermatids/spermatozoa were detected. The expression of CDY1 minor and short transcripts detected in aspirated specimens was less efficient than that in testicular tissue acquired by extraction. It is suggested that CDY2 is apparently required in the early stages of spermatogenesis, whereas CDY1 transcripts are required later on in the process. The findings of this study imply different functional roles for CDY isoforms during spermatogenesis. However, in consideration of the high levels of identity between CDY1 and CDY2 (98% at the protein level), the delayed up-regulation of CDY1 transcripts could be attributable to temporal changes in dosage requirements.

Reduced human germ cell-less (HGCL) expression in azoospermic men with severe germinal cell impairment

Germ cell-less (GCL) protein is a nuclear envelope protein highly conserved between the mammalian and Drosophila orthologues. In Drosophila, maternal GCL protein is required to establish the germ lineage during embryonic development. In mammals, it is suggested that the GCL function is mainly in spermatogenesis and that it might be related to the ability of mouse GCL to repress transcription. Using reverse transcriptase-polymerase chain reaction analyses, we investigated the role of human GCL (HGCL) in spermatogenesis by studying its expression in the testicular tissue of 67 azoospermic men with normal karyotype and no Y-chromosome microdeletion. Their testicular biopsy specimens underwent meticulous histological and cytological analysis as well as molecular analysis with various markers of spermatogenesis (RBM1, DAZ, and CDY1). The rate of X-Y and 18 chromosome bivalent formation during meiosis was additionally assessed in 22 of these biopsy specimens and correlated to HGCL expression. Expression of HGCL was affected in parallel with the severity of testicular impairment found. Defective sperm motility was associated with the absence of HGCL. Nevertheless, the absence of HGCL expression did not influence the normal process of chromosome bivalent formation in meiosis. Our results suggest that HGCL is not essential for the chromosomal events of meiosis but might be involved in later aspects of spermatogenesis.

Localization of the germ cell-specific protein, hnRNP G-T, in testicular biopsies of azoospermic men

The increasing interest in the application of in vitro fertilization techniques in human reproduction has led to a wide use of testicular biopsies to identify the presence of spermatogenic foci in testes of azoospermic men. Histopathologic evaluation of these testicular biopsies is required to determine the spermatogenic state with respect to fertility potential and to rule out preinvasive testicular lesions. Heterogeneous nuclear ribonucleoprotein G-T (hnRNP G-T) is a germ cell-specific protein expressed most prominently during meiosis. We studied the usefulness of hnRNP G-T antibody in the evaluation of these biopsies and reasoned that its germ cell-restricted expression pattern might provide a marker to improve accuracy of diagnosis. Testicular biopsies with various spermatogenic impairments were evaluated immunohistochemically for hnRNP G-T expression. In biopsies exhibiting normal spermatogenesis (obstructive azoospermia), hnRNP G-T was localized in meiotic pachytene spermatocytes and round spermatids. Immunostaining was barely detected when maturation was arrested at the spermatocyte level and not at all in cases of Sertoli cell-only syndrome. Biopsies with a mixed histologic phenotype and minute concentrations of spermatogenesis demonstrated strong immunostaining only in tubules with full spermatogenesis. This distribution pattern of hnRNP G-T enabled instant identification of spermatogenic foci. Thus, exploitation of the hnRNP G-T marker, which is expressed preferentially as meiosis proceeds, enhances sensitivity and accuracy of diagnosis in the histologic evaluation of testicular biopsies.

The expression of mannose-ligand receptor is correlated with sperm morphology

The objective of the present study was to evaluate the association between the expression of sperm mannose-ligand receptors and sperm morphology. Sperm samples were obtained from 45 men, 30 fertile sperm donors and 15 infertile men. Sperm concentration, motility and morphology were evaluated and then incubated with control medium (Ham's F-10 + 1% HSA) for 4 h. Expression of mannose-ligand receptors was evaluated by mannosylated-BSA-FITC (subdivided into 3 patterns: I, for uncapacitated sperm; II, for capacitated; and III, for acrosome-reacted sperm). The mean (+/- SE) frequencies of sperm cells of the total sperm population that expressed patterns I, II, and III were 88 +/- 2.1%, 7 +/- 1.6%, and 5 +/- 0.8%, respectively, for fertile men, and 90 +/- 2.1%, 7 +/- 1.3%, and 3 +/- 0.5%, respectively, for infertile men. The rate of pattern III expression of mannose-ligand receptors was significantly higher in the fertile group compared to the infertile patients (p <.01). A poor but significant correlation was observed between the rate of pattern III and the percentage of normal-forms sperm cell in the ejaculate (r =.35, p =.018). Fertile sperm samples express more advanced patterns of mannose-ligand receptors compared to infertile men. This phenomenon is related to the morphology of human sperm cell in the ejaculate more than to any other basic sperm characteristics.

Probability of sperm detection in nonobstructive azoospermic men undergoing testicular sperm extraction procedures unrelated to clinical parameters

The study was conducted to evaluate the significance of preoperative clinical parameters for detection of mature testicular sperm cells in nonobstructive azoospermic men. Sixty-five consecutive men with nonobstructive azoospermia underwent testicular sperm extraction procedures. Testicular samples were analyzed histologically with patterns classified as mature spermatogenesis (normal or partial), arrest of spermatogenesis, and Sertoli cell only. Testicular sperm cells were isolated for use in an IVF/ICSI program. Histologic patterns and detection rate of sperm cells were correlated to clinical characteristics. Mature sperm cells were found in all levels of serum FSH. The men were divided into 3 groups based on their clinical characteristics (serum FSH level and testicular size). The distribution of the different testicular histologic patterns, as well as detection rate of sperm cells, was similar in all groups. No correlation was found between serum levels of FSH, LH, prolactin, or testosterone and sperm presence. None of these parameters, nor the testicular size and consistency, can serve as predictive variables of the histological pattern or the presence of mature sperm cells in the testicular biopsies in cases of nonobstructive azoospermia. Until an effective predictive tool is available, a trial of sperm retrieval is recommended for all azoospermic men independent of their clinical characteristics.

Sertoli cell maturation in men with azoospermia of different etiologies

OBJECTIVE

To evaluate the involvement of Sertoli cell in different spermatogenic disorders.

DESIGN

Retrospective case-control study.

SETTING

Teaching hospital.

PATIENT(S)

Azoospermic men who underwent testicular biopsy for sperm recovery in preparation for intracytoplasmic sperm injection.

INTERVENTION(S)

Testicular biopsy evaluation by quantitative immunohistochemistry for the immature Sertoli cell markers anti-Müllerian hormone and cytokeratin 18 (CK-18).

MAIN OUTCOME MEASURE(S)

Relative area of immature Sertoli cells in testes with focal spermatogenesis, spermatocyte maturation arrest, or normal spermatogenesis.

RESULT(S)

The relative area occupied by immature Sertoli cells, as revealed by anti-Müllerian hormone and CK-18 expression, was highest in the 11 men with focal spermatogenesis. In the group representing normal spermatogenesis (obstructive azoospermia, 6 men) and in the group characterized by spermatocyte maturation arrest (6 men), the areas occupied by anti-Müllerian hormone- and CK-18-positive cells were minimal.

CONCLUSION(S)

Different etiologies underlie the spermatogenic disorders reported in this study. In focal spermatogenesis with high anti-Müllerian hormone and CK-18 expression, the spermatogenic impairment is associated with the presence of immature Sertoli cells. The detection of normal mature Sertoli cells in the spermatocyte maturation arrest group indicates that the spermatogenic defect that is accompanied by an impairment of meiosis is intrinsic to the germ line without affecting Sertoli cell differentiation.