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

Kinesin-14 KIFC1 promotes acrosome formation and chromatin maturation during mouse spermiogenesis

KIFC1, a member of kinesin-14 subfamily motors, is essential for meiotic cell division and acrosome formation during spermatogenesis. However, the functions of KIFC1 in the formation and maintenance of the acrosome in male germ cells remain to be elucidated. In this study, we report the structural deformities of acrosomes in the in vivo KIFC1 inhibition mouse models. The proacrosomal vesicles diffuse into the cytoplasm and form atypical acrosomal granules. This phenotype is consistent with globozoospermia patients and probably results from the failure of the Golgi-derived vesicle trafficking and actin filament organization. Moreover, the multinucleated and undifferentiated spermatogenic cells in the epidydimal lumen after KIFC1 inhibition reveal the specific roles of KIFC1 in regulating post-meiotic maturation. Overall, our results uncover KIFC1 as an essential regulator in the trafficking, fusion and maturation of acrosomal vesicles during spermiogenesis.

Globozoospermia: A Case Report and Systematic Review of Literature

PURPOSE

Globozoospermia is a genetic syndrome characterized by the presence of round-headed spermatozoa and infertility due to the inability of these spermatozoa to fertilize the oocyte. In this article, we present the clinical case of a young globozoospermic patient with a new, not yet described mutation of the DPY19L2 gene. We also performed a systematic review of the literature on gene mutations, the outcome of assisted reproductive techniques, and the risk of transmission of abnormalities to the offspring in patients with globozoospermia and made recommendations to offer a more appropriate clinical management of these patients.

MATERIALS AND METHODS

We performed a systematic search in the PubMed, Google Scholar, and Scopus databases from their inception to December 2021. The search strategy included the combination of the following Medical Subjects Headings (MeSH) terms and keywords: "globozoospermia", "round-headed spermatozoa", "round head spermatozoa", "intracytoplasmic sperm injection", "ICSI", "offspring", "child health", "assisted reproductive technique outcome". All the eligible studies were selected following the PECOS (Population, Exposure, Comparison/Comparator, Outcomes, Study design) model. The quality of included studies was assessed by applying the "Cambridge Quality Checklists".

RESULTS

The main genes involved in the pathogenesis of globozoospermia are DPY19L2, SPATA16, PICK1, GGN, SPACA1, ZPBP, CCDC62, and CCNB3 genes. Other genes could also play a role. These include C2CD6, C7orf61, CCIN, DNH17, DNH6, PIWIL4, and CHPT1. Globozoospermic patients should undergo ART to achieve fertility. In particular, intracytoplasmic sperm injection with assisted oocyte activation or intracytoplasmic morphologically-selected sperm injection appears to be associated with a higher success rate. Patients with globozoospermia should also be evaluated for the high rate of sperm aneuploidy which appears to influence the success rate of ART but does not appear to be associated with an increased risk of transmission of genetic abnormalities to offspring.

CONCLUSIONS

This systematic review summarizes the evidence on the gene panel to be evaluated, ICSI outcomes, and the health of the offspring in patients with globozoospermia. Evidence-based recommendations on the management of patients with globozoospermia are provided.

Sperm Morphology Assessment in the Era of Intracytoplasmic Sperm Injection: Reliable Results Require Focus on Standardization, Quality Control, and Training

Semen analysis is the first, and frequently, the only step in the evaluation of male fertility. Although the laboratory procedures are conducted according to the World Health Organization (WHO) guidelines, semen analysis and especially sperm morphology assessment is very difficult to standardize and obtain reproducible results. This is mainly due to the highly subjective nature of their evaluation. ICSI is the choice of treatment when sperm morphology is severely abnormal (teratozoospermic). Hence, the standardization of laboratory protocols for sperm morphology evaluation represents a fundamental step to ensure reliable, accurate and consistent laboratory results that avoid misdiagnoses and inadequate treatment of the infertile patient. This article aims to promote standardized laboratory procedures for an accurate evaluation of sperm morphology, including the establishment of quality control and quality assurance policies. Additionally, the clinical importance of sperm morphology results in assisted reproductive outcomes is discussed, along with the clinical management of teratozoospermic patients.

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.

Molecular Analysis of DPY19L2, PICK1 and SPATA16 in Italian Unrelated Globozoospermic Men

This study aims to evaluate genetic contribution and sperm DNA fragmentation (SDF) in a cohort of 18 unrelated globozoospermic Italian men (Group G). Semen samples were assessed according to the WHO 2010 Laboratory Manual and compared with 31 fertile controls. We focused our genetic analysis on the exons of the main globozoospermia-associated genes, performing qualitative PCR to assess deletion of DPY19L2 and sequencing to detect mutations of SPATA16 and PICK1. SDF was evaluated using the TUNEL assay. In Group G, 10 patients had a complete form of globozoospermia, whereas 8 patients had a partial form. Molecular analysis revealed deletion of DPY19L2 in six of the patients, all of them with complete globozoospermia, while no mutations were found in the examined exons of PICK1 and SPATA16. TUNEL analysis showed a higher SDF% in Group G. Our findings confirm DPY19L2 defects as the most frequent genetic alteration in Italian patients contributing to globozoospermic phenotypes. Furthermore, spermatozoa with acrosomal defects could also display high levels of SDF as a possible consequence of abnormally remodeled chromatin. The possible effect on offspring of chromatin structure abnormalities and altered DNA integrity should be carefully evaluated by clinicians, especially regarding the feasibility and safety of artificial reproductive techniques, which represent the only treatment that allows these patients to conceive.

Single-center thorough evaluation and targeted treatment of globozoospermic men

Purpose

To characterize, by specific biomarkers and nucleic acid sequencing, the structural and genomic sperm characteristics of partial (PG) and complete globozoospermic (CG) men in order to identify the best reproductive treatment.

Methods

We assessed spermatozoa from 14 consenting men ultrastructurally, as well as for histone content, sperm chromatin integrity, and sperm aneuploidy. Additional genomic, transcriptomic, and proteomic evaluations were carried out to further characterize the CG cohort. The presence of oocyte-activating sperm cytosolic factor (OASCF) was measured by a phospholipase C zeta (PLCζ) immunofluorescence assay. Couples were treated in subsequent cycles either by conventional ICSI or by ICSI with assisted gamete treatment (AGT) using calcium ionophore (Ionomycin, 19657, Sigma-Aldrich, Saint Louis, MO, USA).

Results

Ultrastructural assessment confirmed complete acrosome deficiency in all spermatozoa from CG men. Histone content, sperm chromatin integrity, and sperm aneuploidy did not differ significantly between the PG (n = 4) and CG (n = 10) cohorts. PLCζ assessment indicated a positive presence of OASCF in 4 PG couples, who underwent subsequent ICSI cycles that yielded a 36.1% (43/119) fertilization with a 50% (2/4) clinical pregnancy and delivery rate. PLCζ assessment failed to detect OASCF for 8 CG patients who underwent 9 subsequent ICSI cycles with AGT, yielding a remarkable improvement of fertilization (39/97; 40.2%) (P = 0.00001). Embryo implantation (6/21; 28.6%) and clinical pregnancies (5/7; 71.4%) were also enhanced, resulting in 4 deliveries. Gene mutations (DPY19L2, SPATA16, PICK1) were identified in spermatozoa from CG patients. Additionally, CG patients unable to sustain a term pregnancy had gene mutations involved in zygote development (NLRP5) and postnatal development (BSX). CG patients who successfully sustained a pregnancy had a mutation (PIWIL1) related to sperm phenotype. PLCZ1 was both mutated and underexpressed in these CG patients, regardless of reproductive outcome.

Conclusions

Sperm bioassays and genomic studies can be used to characterize this gamete’s capacity to support embryonic development and to tailor treatments maximizing reproductive outcome.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10815-021-02191-4.

Association of Zinc deficiency, oxidative stress and increased double-stranded DNA breaks in globozoospermic infertile patients and its implication for the assisted reproductive technique

Background

Sperm DNA fragmentation and its adverse impact on outcomes of assisted reproductive techniques (ART) in globozoospermic infertile patients has been previously reported. However, the association of Zinc element with DNA damage and intracytoplasmic sperm injection (ICSI) outcome in globozoospermic infertile patients remains unclear.

Methods

Using flame atomic absorption spectrophotometer and superoxide dismutase (SOD) assay, the levels of Cu, Fe, Mn, Zn and SOD activities in seminal plasma from both globozoospermic infertile patients and fertile volunteers were tested respectively. Using sperm chromatin dispersion (SCD) test and Comet assay, the DNA damages in their semen samples from the two groups was detected. In addition, using Aniline Blue staining, their sperm nucleus maturations were also examined.

Results

The levels of seminal Zinc and SOD activities were lower in the globozoospermic infertile patients and the double-stranded break DFI (DSB-DFI) were significantly higher than that in the fertile controls. Antioxidative insufficiency of SOD with a low Zn level might be responsible for oxidative stress, which may lead to DNA damage in globozoospermic spermatozoa. Zn deficiency might also have influence on the chromatin stabilization of globozoospermic spermatozoa during spermiogenesis, causing its more vulnerable to oxidative attack.

Conclusions

Serious DSBs in globozoospermia and antioxidative insufficiency due to Zinc element deficiency in spermatozoa might be responsible for the failure of ICSI in globozoospermia.

Sperm parameters, DNA integrity, and protamine expression in patients with type II diabetes mellitus

Diabetes Mellitus (DM) is the most common endocrine disorder affecting many human physiological systems and tissues, including the reproductive organs in men. The age of individuals suffering from this disease has been falling rapidly in recent years. This study compared the effect of DM on sperm parameters, chromatin quality, and apoptosis, as well as the expression profile of protamine genes in men with and without DM using molecular and cytochemical assays. Sixty semen samples from the control group (N = 30) and case group (N = 30) were collected. There was a significant decrease in the percentages of sperm parameters in cases versus the controls (p˂0.05). Despite significantly higher percentages detected in spermatozoa with AB⁺, CMA3⁺, and TUNEL⁺, no change was demonstrated regarding protamines mRNA levels, as well as the P1/P2 ratios in cases in comparison with controls. In contrast, significant positive correlations were found between the quantity of P1 and P2 transcripts (r = 0.944, p < .001). The data indicated that DM not only caused a decrease in the quality of sperm parameters but also affected the sperm maturation process by increasing the substantial implications in the sperm DNA/chromatin levels of DM patients.IMPACT STATEMENTWhat is already known on this subject? Diabetes Mellitus (DM) is a chronic metabolic disorder affecting many human physiological systems and tissues, including the reproductive organs in men. The age of individuals suffering from this disease has been falling rapidly in recent years.What do the results of this study add? We found that DM not only caused a decrease in the quality of the sperm parameters, including motility and concentration, and an increase in morphological abnormalities but also affected the sperm maturation process by increasing the substantial implications in sperm DNA/chromatin levels of DM patients. Despite there being no significant difference in the mRNA levels of protamines between the two groups, our findings showed a positive correlation between the mRNA levels of P1 and progressive sperm motility.What are the implications of these findings for clinical practice and/or further research? Based on the results of this study, chromatin and DNA assessments can have important implications for increasing fertility, as complementary tests, in combination with routine laboratory tests. Since sperm standard parameters are not capable of examining the condition of the sperm nucleus, men with abnormal sperm DNA can also have normal spermatogram, and diabetes is prevalent in reproductive age.

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.

Is there any relationship between human sperm parameters and protamine deficiency in different groups of infertile men?

OBJECTIVE

Abnormality in Histone-Protamine replacements has been indicated to cause sperm DNA damage and infertility. The aim of the present study was to investigate the relationships between sperm parameters in oligospermia, asthenospermia, and teratospermia with protamine deficiency in infertile men.

MATERIAL AND METHOD

In this case-control study, we had three experimental groups including oligospermia (n=100), asthenospermia (n=100), and teratospermia (n=100) as well as normospermia (n=100) as controls. Sperm analyses were performed according to the recommendations of the World Health Organization (WHO, 2010) and sperm chromatin quality was assessed using Chromomycin A3 (CMA3) staining for each sample.

RESULTS

The comparison of the data between groups indicated that the percentage of spermatozoa with protamine deficiency was significantly different in patients with oligospermia, asthenospermia, and teratospermia when compared with control ones. However, there was no significant correlation between sperm nuclear protamine deficiency and their parameters of the men with teratospermia using CMA3 test. Regarding the oligospermia and asthenospermia semen samples, the findings showed the negative correlations between the sperm nuclear protamine deficiency and progressive motility as well as immobility (p<0.001).

CONCLUSION

The higher proportion of spermatozoa with abnormal chromatin packaging was observed in asthenospermic samples than those from other experimental groups as well as controls. It seems that normal morphology cannot have a valuable predictive value for good chromatin quality of spermatozoa, as much as normal motility characteristics, since samples with high mobility rates often have lower protamine deficiencies. The findings may provide a supportable promoting the future wider clinical application of chromatin/DNA integrity testing along with the semen analysis in male infertility.

Comparison of sperm morphology and nuclear sperm quality in SPATA16- and DPY19L2-mutated globozoospermic patients

The aim of this study was to compare the sperm morphology and nuclear sperm quality (sperm aneuploidy and DNA fragmentation) in two groups of globozoospermic patients: DPY19L2-mutated patients (n = 6) and SPATA16-mutated patients (n = 2). Results for these two groups were also compared to a group of fertile men (n = 25). Fluorescence in situ hybridisation was performed for chromosomes X, Y and 18. Sperm DNA fragmentation was evaluated by TUNEL assay. Sanger sequencing was performed for mutations screening of DPY19L2 and SPATA16 genes. Sperm analysis revealed a classic phenotype of total globozoospermia in DPY19L2-mutated group and a particular phenotype characterised by a predominance of double/multiple round-headed (39.00 ± 4.2%) and multi-tailed spermatozoa (26.00 ± 16.97%) in SPATA16-mutated group. FISH analysis showed a significantly higher aneuploidy rate in globozoospermic patients compared to controls (p < 0.05), and a higher rate was observed in SPATA16-mutated group compared to DPY19L2-mutated group (p < 0.05). DNA fragmentation index was significantly higher in globozoospermic men compared to controls (p < 0.001), and there is no statistically significant difference between the two globozoospermic groups. We showed that SPATA16 defects could be associated with an abnormal meiosis leading to a particular morphological sperm defect of double/multiple round-headed and multi-flagella and a higher sperm aneuploidy rate than in case of DPY19L2-defects in classic globozoospermia.

Altered three-dimensional organization of sperm genome in DPY19L2-deficient globozoospermic patients

PURPOSE

To explore the three-dimensional (3D) organization of sperm genome in DPY19L2-deficient globozoospermic patients speculating a link between DPY19L2 and genome organization of sperm nucleus.

METHODS

This is a study of chromatin organization in DPY19L2-deficient globozoospermic patients and healthy donors using three-dimensional fluorescence in situ hybridization (3D-FISH) combined with confocal laser scanning microscopy followed by 3D image analysis. The 3D structures of sperm nuclei, chromocenter, telomeric regions and chromosome territories (CTs), were reconstructed using IMARIS software, and the relative radial position for each individual signal was calculated. Statistical analysis used a non-parametric Mann-Whitney test was appropriate with significance at p < 0.05.

RESULTS

DPY19L2-deficient globozoospermic patients display impaired sperm chromocenter organization resulting in an increased number of chromocenters (5.4 vs 3.5; p < 0.0001). Moreover, radial positions of telomeres are modified with a more central position in globozoospermic nuclei. 3D-FISH analysis of five chromosome territories (CTs) (X, Y, 7, 17, 18) showed that DPY19L2-deficient globozoospermic sperm nuclei display altered spatial organization of CT X, CT 7 and CT 18.

CONCLUSIONS

Our findings strengthen the hypothesis that DPY19L2 might be considered as a LINC-like protein having a crucial role in the organization of nuclear chromatin in sperm nucleus through its interaction with nuclear lamina. Our results might also explain defective embryonic development after intracytoplasmic sperm injection (ICSI) performed with DPY19L2-deficient globozoospermic sperm.

Abnormal retention of nuclear lamina and disorganization of chromatin-related proteins in spermatozoa from DPY19L2-deleted globozoospermic patients

The aim of this study was to characterize the nuclear lamina (NL) and lamin chromatin-partners in spermatozoa from four DPY19L2-deleted globozoospermic patients. We tested for spermatid transcripts encoding lamins and their chromatin-partners emerin, LAP2α, BAF and BAF-L, by reverse transcriptase-PCR using spermatozoa RNA. We also determined the localization of lamin B1, BAF and BAF-L by immunofluorescent analysis of spermatozoa from all patients. In RNA from globozoospermic and control spermatozoa we detected transcripts encoding lamin B1, lamin B3, emerin, LAP2α and BAF-L, but not A-type lamins. In contrast, BAF transcripts were detected in globozoospermic but not control spermatozoa. The NL was immature in human globozoospermic spermatozoa: lamin B1 signal was detected in the nuclei of globozoospermic spermatozoa in significantly higher proportions than the control (P < 0.05; 56-91% versus 40%) and was predominantly observed at the whole nuclear periphery, not polarized as in control spermatozoa. Conversely, BAF and BAF-L were detected in control, but not globozoospermic spermatozoa. Our results strongly emphasize the importance of the NL and associated proteins during human spermiogenesis. In globozoospermia, the lack of maturation of the NL, and the modifications in expression and location of chromatin-partners, could explain the chromatin defects observed in this rare phenotype.

Association between total globozoospermia and sperm chromatin defects

Globozoospermia is a severe sperm morphological anomaly leading to primary infertility and low fertilisation following intracytoplasmic sperm injection (ICSI). This phenotype is observed in less than 0.1% of infertile men and is determined by small, round-headed spermatozoa with absence of an acrosomal cap, acrosome protease and also cytoskeletal proteins. Failure of oocyte activation is considered as the main cause of fertilisation failure in these individuals post-ICSI. Therefore, artificial oocyte activation (AOA) along with ICSI is commonly implemented. However, based on previous report, fertilisation rate remains low despite implementation of ICSI-AOA. Therefore, other mechanisms like sperm chromatin packaging and DNA fragmentation may account for low fertilisation and development post-ICSI-AOA. Therefore, this study aims to assess and compare the degree of sperm protamine deficiency and DNA fragmentation in large population of infertile men with total globozoospermia (30 globozoospermic men presenting with 100% round-headed spermatozoa) with 22 fertile individuals using chromomycin A3 and TUNEL assay respectively. Results clearly show that mean of sperm concentration and percentage of sperm motility were significantly lower, while percentage of sperm abnormal morphology, protamine-deficient and DNA-fragmented spermatozoa were significantly higher in infertile men with globozoospermia compared to fertile men. Therefore, increased sperm DNA damage in globozoospermia is likely related to defective DNA compaction and antioxidant therapy before ICSI-AOA could be recommended as an appropriate option before ICSI-AOA.

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.

Evaluation of sperm nuclear integrity in patients with different percentages of decapitated sperm in ejaculates

The decapitated sperm defect is a rare type of teratozoospermia responsible for male infertility. Spermatozoa from patients affected by this syndrome are used for intracytoplasmic sperm injection (ICSI) although little is known about their DNA integrity. This study evaluated sperm nuclear alterations in four patients and ten fertile men (control group). Sperm samples were examined by light, transmission electron and high-magnification contrast microscopy and analysed after terminal deoxynucleotidyltransferase-mediated dUTP nick end labelling, aniline blue staining and fluorescence in-situ hybridization. Spermatozoa from patients presented varying degrees of decapitation, along with morphological and ultrastructural head abnormalities. Whereas the proportion of spermatozoa with fragmented DNA and numerical chromosome abnormalities was similar in patients 1-3 and controls, the percentage of spermatozoa with hypocondensed chromatin was higher in patients 1-3 than in fertile men. Patient 4 presented a distinct phenotype, with an increased proportion of flagellated spermatozoa with DNA strand breaks as well as increased aneuploidy and diploidy rates compared with controls and with patients 1-3. No successful pregnancy resulted from ICSI although embryos were obtained for three patients. The morphological defects and the nuclear alterations observed in spermatozoa of patients with the decapitated sperm syndrome may have contributed to ICSI failures.

Dpy19l2-deficient globozoospermic sperm display altered genome packaging and DNA damage that compromises the initiation of embryo development

We recently identified the DPY19L2 gene as the main genetic cause of human globozoospermia. Non-genetically characterized cases of globozoospermia were associated with DNA alterations, suggesting that DPY19L2-dependent globozoospermia may be associated with poor DNA quality. However the origins of such defects have not yet been characterized and the consequences on the quality of embryos generated with globozoospermic sperm remain to be determined. Using the mouse model lacking Dpy19l2, we compared several key steps of nuclear compaction. We show that the kinetics of appearance and disappearance of the histone H4 acetylation waves and of transition proteins are defective. More importantly, the nuclear invasion by protamines does not occur. As a consequence, we showed that globozoospermic sperm presented with poor sperm chromatin compaction and sperm DNA integrity breakdown. We next assessed the developmental consequences of using such faulty sperm by performing ICSI. We showed in the companion article that oocyte activation (OA) with globozoospermic sperm is very poor and due to the absence of phospholipase Cζ; therefore artificial OA (AOA) was used to bypass defective OA. Herein, we evaluated the developmental potential of embryos generated by ICSI + AOA in mice. We demonstrate that although OA was fully rescued, preimplantation development was impaired when using globozoospermic sperm. In human, a small number of embryos could be generated with sperm from DPY19L2-deleted patients in the absence of AOA and these embryos also showed a poor developmental potential. In conclusion, we show that chromatin compaction during spermiogenesis in Dpy19l2 KO mouse is defective and leads to sperm DNA damage. Most of the DNA breaks were already present when the sperm reached the epididymis, indicating that they occurred inside the testis. This result thus suggests that testicular sperm extraction in Dpy19l2-dependent globozoospermia is not recommended. These defects may largely explain the poor embryonic development of most mouse and human embryos obtained with globozoospermic sperm.