Total Globozoospermia Research Articles

P-039 Pregnancy outcomes and genetic analysis of globozoospermic patients: A case series and review of the literature

Abstract Study question How should men with globozoospermia be managed in Assisted Reproductive Technologies (ART)? Summary answer IMSI (intracytoplasmic morphologically selected sperm injection), without oocyte activators (OA) allows to obtain a live birth, even when there is a mutation of DPY19L2 gene. What is known already Globozoospermia is a rare syndrome found in less than 0.1% of the infertile population. It is characterized by the presence of spermatozoa with round heads devoid of acrosomes. Two main genes are involved in the transmission of the disease: SPATA 16 and DPY19L2. Only Assisted Reproductive Technologies (ART) such as ICSI (intra-cytoplasmic sperm injection) and IMSI, with or without OA allow these couples to obtain pregnancies. There are no live births described after IMSI without OA in patients with a DPY19L2 mutation. Study design, size, duration Four infertile couples followed in the Department of ART at the Poissy Hospital Center, were studied between 2011 and 2022.All patients had total globozoospermia. Three patients were tested for the DPY19L2 gene mutation. Patients were managed in ART with the IMSI technique without the use of OA. Participants/materials, setting, methods The first patient had a homozygous mutation of the DPY19L2 gene. Two live births were obtained after IMSI. The second patient was not DPY19L2 mutated. 2 IMSI were performed, resulting in a biochemical pregnancy. The third patient had a homozygous mutation of the DPY19L2 gene. An IMSI was performed without obtaining a pregnancy, a second attempt is scheduled soon. The fourth patient refused genetic testing and IMSI management. Sperm donation was performed without achieving pregnancy. Main results and the role of chance In this case series, we present the management of four globozoosperm couples in the Reproductive Biology and Andrology Department at the Poissy Hospital Center. We also present the first two live births after performing an IMSI, without OA, in a globozoospermic patient with a homozygous mutation of DPY19L2 gene. In fact, according to our review of the literature, 53 case reports or articles of patients having benefited from ART with or without OA have been reported in globozoospermic patients. In these couples, 60 children were born. However, no live births had been reported until now in couples managed in IMSI without OA, where men had globozoospermia with DPY19L2 mutation. Limitations, reasons for caution The use of OA to increase the membrane permeability of oocyte to calcium and increase fertilization rates. The highest number of live births in the globozoosperm population occurs after ICSI or IMSI with OA. There is no described live birth without the use of OA in a DPY19L2 mutated patient. Wider implications of the findings The use of OA remains debated and is not authorized in some countries. Although our study found low fertilization rates after IMSI, it’s possible to obtain live births. The selection of spermatozoa with an acrosome outline at high magnification is thus an interesting alternative to the use of oocyte activators. Trial registration number not applicable

INVESTIGATION OF GLOBOZOOSPERMIA’S MORPHOLOGICAL STRUCTURE AND DNA FRAGMENTATION IN OLIGOZOOSPERMIA CASES IN INFERTILE MALES

Total globozoospermia is diagnosed by the presence of 100% round-headed spermatozoa without acrosomes. It is still unclear whether patients whose ejaculate contains both normal and globozoospermic cells (partial globozoospermia) suffer from a variation of the same syndrome. Affected men may experience decreased fertility and even infertility. In some cases, an increased number of cells with DNA fragmentation has also been observed in patients with globozoospermia..In this study, standard semen analysis methods in accordance with WHO criteria were applied to infertile male patient groups consisting of 20 normozoospermic and 20 oligozoospermic individuals who were admitted to our clinic. Age, sperm parameters (volume, vitality, concentration, total motility and morphology) were determined and statistically analyzed in normozoospermic and oligozoospermic infertile men.Sperms were stained with the Eosin-Nigrosin method and were visualized under an immersion lens light microscope and evaluated for vitality. The slides were stained using sperm staining solutions with the Spermac technique and the sperms were evaluated morphologically. Sperm DNA fragmentation damage was evaluated by acridine orange staining method.Our results revealed that sperm morphological features (Kruger test) and sperm DNA fragmentation, obtained with various staining techniques, are important in the clinical approach to male infertility and ART methods, and should be used together.

Genome-wide compound heterozygote analysis highlights DPY19L2 alleles in a non-consanguineous Spanish family with total globozoospermia

Research questionWould the use of genome-wide genotyping be an advantageous strategy to identify the molecular aetiology of two brothers from a non-consanguineous family, clinically diagnosed with total globozoospermia? DesignTwo related Spanish globozoospermic patients were studied. Eight first- and second-degree family members were also included in the study. The clinical procedure included anamnesis, physical examination and semen analyses. Acrosome visualization was performed by fluorescein isothiocyanate–Pisum sativum agglutinin labelling and ultrastructural electron microscope sperm analysis. Sperm DNA fragmentation was determined by TUNEL and SCD. Molecular analysis included: the detection of deletion of the DPY19L2 gene by a BPa (break point "a") gap-polymerase chain reaction, and genotyping by using a high-throughput genome-wide genotyping platform and a genotype imputation strategy. ResultsThe biological characteristics of the two globozoospermic siblings included round-headed spermatozoa without an acrosome; ultrastructural defects in spermatozoa; increased sperm fragmentation and aneuploidies, inability of spermatozoa to activate oocytes (correctable with artificial activation) and good developmental potential of embryos generated by IVF/intracytoplasmic sperm injection. This genetic study focused on a genome-wide compound heterozygote analysis that identified two deleterious rare coding variants in the DPY19L2 gene [rs771726551 (c.431T>A exon 3) and rs147579680 (c.869G>A exon 8)]. ConclusionA genome-wide compound heterozygote analysis strategy should be considered for molecular screening in globozoospermia and other rare congenital diseases, particularly in cases from non-consanguineous families.

Immunofluorescence and High-Resolution Microscopy Reveal New Insights in Human Globozoospermia.

Globozoospermia is a rare and severe type of teratozoospermia characterized by the presence of round-headed, acrosomeless spermatozoa with cytoskeleton defects. Current data support a negative relationship between globozoospermia and intracytoplasmic sperm injection (ICSI) outcomes, revealing the need to perform exhaustive studies on this type of sperm disorder. The aim of this study was to evaluate different structural, functional and molecular sperm biomarkers in total globozoospermia with proper embryo development after ICSI. The combination of field-emission scanning electron microscopy (FE-SEM) and transmission electron microscopy (TEM) allowed us to identify and correlate eight morphological patterns with both types of microscopy. Additionally, results reported a high percentage of coiled forms, with cytoplasmic retentions around the head and midpiece. By fluorescent microscopy, we detected that most of the sperm showed tubulin in the terminal piece of the flagellum and less than 1% displayed tyrosine phosphorylation in the flagellum. Moreover, we did not detect chaperone Heat shock-related 70 kDa protein 2 (HSPA2) in 85% of the cells. Overall, these findings provide new insights into globozoospermia, which could have potential implications in improving sperm selection methods for assisted reproductive techniques.

Original Research: Expression Profile of CAPZA3 And TR-KIT Genes in Men with Globozoospermia & Asthenoteratospermia that Undergo ICSI Protocol

Objective(s): Sperm-mediated oocyte activation depends upon suitable expression and assembly of sperm-borne oocyte-activating factors (SOAFs) during spermiogenesis. Several factors have been considered as candidates for oocyte activation in recent years. Globozoospermia is a severe sperm morphology disorder that is a rare type of teratozoospermia with an incidence of 0.1% among infertile individuals. testis-specific genes including CAPZA3 [capping protein (actin filament) muscle Z-line, alpha, which is considered as a nominee for sperm associated oocyte activating factors, an actin-capping protein, controlling actin polymerization during spermiogenesis. They contain a common bidirectional promoter. Another gene TR-KIT (a truncated form of the KIT receptor) which is a major sperm-associated oocyte-activating factor. The objective of this study was to investigate the expression profile of CAPZA3 and TR-KIT mRNA, in men with total globozoospermia, Asthenoteratospermia, and fertile individuals.
 Materials and Methods: Semen samples were collected from three groups including 25 fertile men, 20 Asthenoteratospermia and 12 Globozoospermia that undergo intra-cytoplasmic sperm injection (ICSI), Expression of CAPZA3 and TR-KIT were assessed by Real time PCR.
 Results: Individuals with Globozoospermia have presented significantly lower expression of CAPZA3 and TR-KIT mRNA when compared with fertile men. Asthenoteratospermia (male factor) showed significantly lower expression of CAPZA3 mRNA, whereas non-significantly of TR-KIT mRNA. Levels of CAPZA3 and TR-KIT mRNA in the spermatozoa of fertile men were significantly higher than the corresponding values of the globozoospermic and Asthenoteratospermia subjects.
 Conclusion: Analysis mRNA of CAPZA3 gene maybe assist the researcher to identify individuals with a lack of ability to induce oocyte activation and make them a candidate for artificial oocyte activation and help researcher to identify genetic defects associated with failed fertilization. whereas, mRNA of TR-KIT gene appears inability to induce oocyte activation

Deletion of dpy-19 like 2 (DPY19L2) gene is associated with total but not partial globozoospermia.

The dpy-19 like 2 (DPY19L2) gene is the most common genetic cause of globozoospermia characterised by the production of round-headed spermatozoa without an acrosome. The present study was performed on 63 men with globozoospermia and 41 normozoospermic individuals to evaluate the frequency of the DPY19L2 gene and exons; deletion and genetic changes in exons 1, 5, 7-11, 19, 21 and interval introns; and some epidemiological factors (e.g. varicocele, smoking, drug use, alcohol consumption and a family history of infertility). Homozygous deletion of DPY19L2 was identified in 35% of men with globozoospermia. Exon 7 was deleted in 4.8% of men with globozoospermia in which DPY19L2 was not deleted. No genetic variations were observed within the DPY19L2 exons examined, but five intronic polymorphisms were detected: 1054-77T>C in intron 9, 1131+65T>C and 1131+53A>G in intron 10 and 1218+22T>C and 1218+73T>C in intron 11. There were significant differences in the frequency of 1054-77T>C and 1218+22T>C polymorphisms between the globozoospermic and normozoospermic groups. In addition, there were significant differences between the two groups in sperm count, sperm motility, a history of infertility in the family and varicocele. Based on these findings, DPY19L2 deletion is the major cause of total globozoospermia and there is no association between exons 1, 5, 8-11, 19 and 21 polymorphisms of the DPY19L2 gene in the occurrence of this defect.

Corrigendum to: Deletion of dpy-19 like 2 (DPY19L2) gene is associated with total but not partial globozoospermia.

The dpy-19 like 2 (DPY19L2) gene is the most common genetic cause of globozoospermia characterised by the production of round-headed spermatozoa without an acrosome. The present study was performed on 63 men with globozoospermia and 41 normozoospermic individuals to evaluate the frequency of the DPY19L2 gene and exons; deletion and genetic changes in exons 1, 5, 7-11, 19, 21 and interval introns; and some epidemiological factors (e.g. varicocele, smoking, drug use, alcohol consumption and a family history of infertility). Homozygous deletion of DPY19L2 was identified in 35% of men with globozoospermia. Exon 7 was deleted in 4.8% of men with globozoospermia in which DPY19L2 was not deleted. No genetic variations were observed within the DPY19L2 exons examined, but five intronic polymorphisms were detected: 1054-77T>C in intron 9, 1131+65T>C and 1131+53A>G in intron 10 and 1218+22T>C and 1218+73T>C in intron 11. There were significant differences in the frequency of 1054-77T>C and 1218+22T>C polymorphisms between the globozoospermic and normozoospermic groups. In addition, there were significant differences between the two groups in sperm count, sperm motility, a history of infertility in the family and varicocele. Based on these findings, DPY19L2 deletion is the major cause of total globozoospermia and there is no association between exons 1, 5, 8-11, 19 and 21 polymorphisms of the DPY19L2 gene in the occurrence of this defect.

Globozoospermia syndrome: An update.

Among the factors involved in male infertility, there is a rare morphology disorder called "globozoospermia" that is classified into total globozoospermia and partial globozoospermia (type I and type II, respectively). This syndrome is primarily characterised by the presence of round-headed spermatozoa with cytoskeleton defects around the nucleus and no acrosome. Current data support the negative correlation between globozoospermia and conventional intracytoplasmic sperm injection (ICSI) outcomes, revealing the need for the management of patients undergoing assisted reproduction technology (ART) through more effective treatment techniques. This review highlights the most important characteristics of globozoospermia such as sperm parameters, DNA/chromatin integrity and sperm DNA fragmentation (SDF), as well as genetic features based on the latest knowledge. Additionally, we looked into current progress on fertilisation potential and possible treatment strategies for patients presenting with globozoospermia.

The clinical case of infertility treatment caused by male factor (globozoospermia type 1) by the intracytoplasmic morphologically normal sperm injection with activation of the oocytes by Ca2+-ionophore

A case of infertility treatment in couple with a male factor, the severe form of teratozoospermia (total globozoospermia (type 1)) was presented. This pathology is extremely rare (0.1 % at andrological patients). Globozoospermia (type 1) is an insufficiently studied disease and is a severe disorder of spermatogenesis that leads to 100 % of male infertility. Assisted reproductive technologies with using of intracytoplasmic morphologically normal sperm injection and the activation of oocytes – by Ca2+-ionophore A23187 in a man with globozoospermia (type 1) helped in the treatment of infertility in matrimony. Pregnancy and childbirth proceeded favorably.

Proteomic Analysis of Dpy19l2-Deficient Human Globozoospermia Reveals Multiple Molecular Defects.

To investigate the differences in protein expression between Dpy19l2-deficient human globozoospermia and normozoospermia. Human sperm samples from three globozoospermic donors with Dpy19l2 deletion and three normal controls are subjected to TMT quantitative technology. SPESP1, HIST1H4A, and LYZL1 are randomly selected for western blotting analysis. GO annotations are performed using the Database for Annotation, Visualization, and Integrated Discovery. A total of 2567 proteins are identified, of which 2510 proteins are quantified, and 491 are differentially expressed (fold-change >2), with 370 upregulated and 121 downregulated in globozoospermic patients. The levels of several important proteins, including SPACA 1, IZUMO1, ZPBP1, and PLCZ1, are decreased in globozoospermic sperm. Bioinformatics analysis indicates the Dpy19l2-deficient sperm presented molecular defects in acrosome, chromatin, sperm-egg interaction, and fertilization. The present study is the first to analyze total globozoospermia with Dpy19l2 deletion using high-throughput proteomics. This study may provide insights into the mechanism of globozoospermia.

Sperm chromatin quality and DNA integrity in partial versus total globozoospermia

Globozoospermia is a severe form of teratozoospermia with low incidence in infertile patients, considered as one of the important causes of male infertility. The objective was to investigate the chromatin/DNA integrity as well as apoptosis in ejaculated spermatozoa of cases with partial or total globozoospermia. Fifty-seven semen samples were divided into three groups of partial globozoospermia (n=17), total globozoospermia (n=10) and normozoospermia (control; n=30). Sperm chromatin condensation, DNA integrity and apoptosis were assessed using cytochemical assays. The results showed significant differences in sperm parameters of count and motility between two case groups versus controls. The percentages of spermatozoa with abnormal chromatin packaging and protamine deficiency were significantly higher in total and partial globozoospermic men compared to normozoospermic samples. Also, the rates of TUNEL-positive spermatozoa were significantly increased in both globozoospermic cases with respect to the control (18.3±10.1 and 12.3±9.2 versus 5.9±3 respectively). However, no significant differences were noticed between two subgroups of patients with regard to sperm DNA denaturation, DNA fragmentation and apoptosis. Abnormal chromatin packaging, DNA damage and apoptosis were significantly higher in cases than controls. The sperm chromatin/DNA anomalies may be considered as one of the main aetiology of ART failure in globozoospermic patients.

Expression profile ofPLCζ,PAWP,andTR-KITin association with fertilization potential, embryo development, and pregnancy outcomes in globozoospermic candidates for intra-cytoplasmic sperm injection and artificial oocyte activation

Sperm-mediated oocyte activation critically depends upon appropriate expression and assembly of sperm-borne oocyte-activating factors (SOAFs) during spermiogenesis. Several factors have been considered as candidate for SOAFs over the recent years. However, little is known about the expression profile of these candidates and their potential contribution to the clinical outcomes of intra-cytoplasmic sperm injection (ICSI), particularly in globozoospermia. This study investigated the expression profile of PLCζ, PAWP, and TR-KIT and clinical outcomes of ICSI in 12 men with total globozoospermia and compared with 12 fertile individuals. Levels of PLCζ, PAWP, and TR-KIT mRNA in the spermatozoa of fertile men were significantly higher than the corresponding values of the globozoospermic subjects. Interestingly, at protein level, expressions of these factors in the cases assessed were low in globozoospermic individuals. Fertilization rates following artificial oocyte activation (AOA) in the majority of globozoospermic couples were higher than the expected 30% cut-off value reported for individuals with failed or low fertilization rate. Clinical outcomes of ICSI-AOA were dependent on inter-individual variation in globozoospermic couples. None of the SOAFs assessed could provide a greater prediction value with respect to fertilization rate in globozoospermic couples which underwent ICSI-AOA. High fertilization (56.06%) and pregnancy (41.7%) rates accomplished in this study following ICSI-AOA indicated that expression profiles of PLCζ, PAWP, and TR-KIT were low in globozoospermic individuals, and ICSI combined with artificial oocyte activation could mimic physiological calcium changes which occur during fertilization.

First successful pregnancy in a globozoospermic patient having homozygous mutation in SPATA16

To report the first case of a successful pregnancy obtained with an infertile 29-year-old man with a homozygous mutation in the spermatogenesis-specific gene SPATA16 after intracytoplasmic sperm injection (ICSI). Case report. Assisted reproductive technology (ART) center. A couple who suffered from infertility of whom the husband was globozoospermic and carrying a homozygous mutation in the spermatogenesis-specific gene SPATA16. Clinical and histopathological evaluation, transmission electron microscopy, stimulation with fixed antagonist protocol, ICSI, activation of fertilization. Invitro fertilization and pregnancy. Oligoasthenoteratozoospermia was revealed in semen analysis. Total globozoospermia was detected. Chromatin condensation pattern was detected abnormal in 88% of spermatozoa with aniline blue staining. During the ART cycle 12 oocytes were collected. Eleven oocytes were at the metaphase II and one was at the germinal vesicle stage. After the injection, one oocyte fertilized on the following day; the 4-cell stage embryo was transferred. Pregnancy occurred and a healthy boy was delivered after 42weeks of gestation. This is the first report of a pregnancy obtained in a man with homozygous SPATA16 mutated globozoospermia.

Total globozoospermia associated with increased frequency of immature spermatozoa with chromatin defects and aneuploidy: a case report

Globozoospermia, characterised by the presence of round spermatozoa lacking acrosomes in an ejaculate, is a known cause of male infertility. Semen analysis, including sperm chromatin structure assay, toluidine blue, chromomycin A3 and aniline blue staining and fluorescence in situ hybridisation, was performed in an infertile globozoospermic patient to establish to which extent these genetic factors contributed to his infertility. No spermatozoa capable of hyaluronan (HA) binding were detected in the HA binding assay. Increased rates of immature spermatozoa with defective replacement of histones by protamines, DNA breaks and disturbed chromatin integrity and sperm aneuploid for the sex chromosomes were observed. Intracytoplasmic sperm injection (ICSI) was used in three in vitro fertilisation (IVF) cycles, and enough morphologically well-developing embryos were obtained in each cycle. However, no pregnancy was achieved. The infertility of our couple, resistant to IVF/ICSI treatment, was most probably caused by a combination of male and female factors.

A Homozygous Deletion of the DPY19L2 Gene is a Cause of Globozoospermia in Men From the Republic of Macedonia

Globozoospermia is a rare but severe teratozoospermia, characterized by ejaculates consisting completely of round-headed spermatozoa that lack an acrosome or, in partial globozoospermia, containing a variable proportion (20.0-90.0%) of acrosomeless spermatozoa. Men that are affected with total globozoospermia are infertile, and even the application of intracytoplasmic sperm injection (ICSI) has met with disappointingly low success rates. In humans, several case reports of globozoospermia have demonstrated that two or more siblings were affected in each family, which suggested a genetic component to this disease. Currently, three genes are known to be associated with total globozoospermia in humans, SPATA16 , PICK1 and DPY19L2 genes. Mutations in SPATA16 and PICK1 are rare causes of globozoospermia, found in only one patient each. Several studies have suggested that DPY19L2 mutations are the major cause of globozoospermia in patients from different ethnic origins and different geographic regions. The most common DPY19L2 mutation is the 200 kb deletion arising from a nonallelic homologous recombination (NAHR) between the flanking low copy repeats (LCRs). Here we describe the presence of a homozygous deletion of the DPY19L2 gene in two infertile Macedonian patients with 100.0% round headed spermatozoa, thus suggesting that this deletion represents a major cause of globozoospermia among Macedonian men.

Sperm cephalic vacuoles: new arguments for their non acrosomal origin in two cases of total globozoospermia

To add new arguments concerning the origin of the sperm-head vacuoles observed under high magnification with interference contrast microscopy, we carried out in two patients with total globozoospermia confirmed using transmission electron microscopy (TEM), a detailed sperm morphometric analysis with high magnification (×6000) under Nomarski contrast, an acrosomal status analysis (using fluorescent labelling with peanut agglutinin (PNA) lectins and anti-CD46 antibodies) and a nuclear status analysis (using terminal deoxynucleotidyl transferase-mediated dUTP nick-end labelling assay TUNEL, sperm chromatin structure assay SCSA and aniline blue staining). Our two patients with globozoospermia had relative sperm vacuole areas of 6.3% and 5%, similar to those observed in a reference population of 12 fertile men (5.9%). TUNEL and SCSA assays gave normal results in both patients, although the percentage of immature nuclei using aniline blue staining was increased (27 and 46% for patient 1 and 2 respectively). Cytofluorescence and TEM analysis evidence differences between the two patients: although no acrosomal neither Golgi residue could be detected in patient 1, patient 2 had positive PNA lectin labelling for 9% of spermatozoa and Golgi residues were seen using electron microscopy. Unlike patient 1, a live birth could be obtained after intracytoplasmic sperm injection (ICSI) for patient 2. This descriptive study of two patients with total globozoospermia confirmed using TEM argue in favour of a deep analysis of total globozoospermia before assisted reproductive technology and provides further information on the non-acrosomal origin of the sperm-head vacuoles observed under high magnification.

Successful childbirth after intracytoplasmic morphologically selected sperm injection without assisted oocyte activation in a patient with globozoospermia

We here report a successful pregnancy and healthy childbirth obtained in a case of total globozoospermia after intracytoplasmic morphologically selected sperm injection (IMSI) without assisted oocyte activation (AOA). Two semen analyses showed 100% globozoospermia on classic spermocytogram. Motile sperm organelle morphology examination (MSOME) analysis at ×10,000 magnification confirmed the round-headed aspect for 100% of sperm cells, but 1% of the spermatozoa seemed to present a small bud of acrosome. This particular aspect was confirmed by transmission electron microscopy and anti-CD46 staining analysis. Results from sperm DNA fragmentation and fluorescence in situ hybridization analyses were normal. The karyotype was 46XY, and no mutations or deletions in SPATA16 and DPY19L2 genes were detected. Considering these results, a single IMSI cycle was performed, and spermatozoa were selected for the absence of vacuoles and the presence of a small bud of acrosome. A comparable fertilization rate with or without calcium-ionophore AOA was observed. Two fresh top-quality embryos obtained without AOA were transferred at Day 2 after IMSI, leading to pregnancy and birth of a healthy baby boy. This successful outcome suggests that MSOME may be useful in cases of globozoospermia in order to carefully evaluate sperm morphology and to maximize the benefit of ICSI/IMSI.

Morphology of Partial Globozoospermia

Total globozoospermia is a rare sperm morphology disorder that consists of 100% round-headed, acrosomeless spermatozoa. There is also a larger group of patients whose sperm cells are partially acrosomeless. The aim of this investigation was to describe partial globozoospermia compared to total globozoospermia and normozoospermia. Ejaculates from 10 patients with more than 50% acrosomeless spermatozoa (partial globozoospermia), 3 patients with total globozoospermia, and 9 normozoospermic controls were analyzed with light microscopy, transmission electron microscopy, and flow cytometry. Qualitative and quantitative examination of spermatozoa from the 3 groups shows differences in the percentage of round-headed sperm cells and acrosome malformation. Total globozoospermia presents as a homogenous kind of teratozoospermia. Partial globozoospermia is a distinctive sperm malformation with an increased proportion of round-headed sperm cells and acrosome malformations compared to normozoospermia, which exists separately from total globozoospermia. It thereby contains oval sperm cells that may have distinctive malformations of the sperm head matrix, but also morphologically normal sperm cells that may be used in a clinical setting.

A Recurrent Deletion of DPY19L2 Causes Infertility in Man by Blocking Sperm Head Elongation and Acrosome Formation

An increasing number of couples require medical assistance to achieve a pregnancy, and more than 2% of the births in Western countries now result from assisted reproductive technologies. To identify genetic variants responsible for male infertility, we performed a whole-genome SNP scan on patients presenting with total globozoospermia, a primary infertility phenotype characterized by the presence of 100% round acrosomeless spermatozoa in the ejaculate. This strategy allowed us to identify in most patients (15/20) a 200 kb homozygous deletion encompassing only DPY19L2, which is highly expressed in the testis. Although there was no known function for DPY19L2 in humans, previous work indicated that its ortholog in C.elegans is involved in cell polarity. In man, the DPY19L2 region has been described as a copy-number variant (CNV) found to be duplicated and heterozygously deleted in healthy individuals. We show here that the breakpoints of the deletions are located on a highly homologous 28 kb low copy repeat (LCR) sequence present on each side of DPY19L2, indicating that the identified deletions were probably produced by nonallelic homologous recombination (NAHR) between these two regions. We demonstrate that patients with globozoospermia have a homozygous deletion of DPY19L2, thus indicating that DPY19L2 is necessary in men for sperm head elongation and acrosome formation. A molecular diagnosis can now be proposed to affected men; the presence of the deletion confirms the diagnosis of globozoospermia and assigns a poor prognosis for the success of invitro fertilization.

Globozoospermia revisited

Globozoospermia is a rare (incidence <0.1%) but severe disorder in male infertility. Total globozoospermia is diagnosed by the presence of 100% round-headed spermatozoa lacking an acrosome. It is still unclear whether patients whose ejaculate contains both normal and globozoospermic cells (partial globozoospermia) suffer from a variation of the same syndrome. Apart from the fact that affected males suffer from reduced fertility or even infertility, no other physical characteristics can be associated with the syndrome. ICSI is a treatment option for these patients, although low fertilization rates after ICSI show a reduced ability to activate the oocyte. In globozoospermic cells, the use of acrosome markers has demonstrated an absent or severely malformed acrosome. Chromatin compaction appears to be disturbed but is not consistently over- or undercondensed. In some cases, an increased number of cells with DNA fragmentation have been observed. The analysis of the cytogenetic composition revealed an increased aneuploidy rate in some cases. Nonetheless, no increased number of spontaneous abortions or congenital defects has been reported in pregnancies conceived after ICSI. The pathogenesis of globozoospermia most probably originates in spermiogenesis, more specifically in acrosome formation and sperm head elongation. In several knockout mouse models, a phenotype similar to that in humans was found. Together with the occurrence of affected siblings, these findings indicate a genetic origin, which makes globozoospermia a good candidate for genetic analysis. More research is needed to elucidate the pathogenesis of human globozoospermia to further understand globozoospermia as well as (abnormalities in) spermiogenesis and spermatogenesis in general.