Identification of nonfunctional SPATA20 causing acephalic spermatozoa syndrome in humans.

Acephalic spermatozoa syndrome (ASS) is a rare and severe type of teratozoospermia characterized by the predominance of headless spermatozoa in the ejaculate. However, knowledge about the causative genes associated with ASS in humans is limited. Loss-of-function of SPATA20 has been suggested to result in the separation of the sperm head and flagellum in mice, whereas there have been no cases reporting SPATA20 variants leading to human male infertility. In this study, a nonsense mutation in SPATA20 (c.619C > T, p.Arg207*) was first identified in an ASS patient. Moreover, this variant contributed to the degradation of SPATA20 and was associated with decreased expression of SPATA6, which plays a vital role in the assembly of the sperm head-tail conjunction in humans. In addition, the infertility caused by loss-of-function mutation of SPATA20 might not be rescued by intracytoplasmic sperm injection (ICSI). Collectively, our findings suggested that SPATA20 might be required for sperm head-tail conjunction formation in humans, the nonfunction of which may lead to male infertility related to ASS. The discovery of the loss-of-function mutation in SPATA20 enriches the gene variant spectrum of human ASS, further contributing to improved diagnosis, genetic counseling and prognosis for male infertility.

[Intracytoplasmic sperm injection for patients with special types of teratozoospermia: Analysis of outcomes].

OBJECTIVE: To investigate the outcomes of intracytoplasmic sperm injection (ICSI) in the treatment of special types of teratozoospermia such as globozoospermia, acephalic spermatozoa syndrome (ASS) and multiple morphological abnormalities of sperm flagella (MMAF). METHODS: We retrospectively analyzed the clinical data on 7 cases of globozoospermia (group A), 6 cases of ASS (group B) and 21 cases of MMAF (group C) treated by ICSI from January 2011 to January 2021, all confirmed with pathogenic or likely pathogenic gene variations. We compared the age, body mass index (BMI), sperm parameters, number of mature oocytes, and rates of fertilization, high-quality embryos, clinical pregnancy, live birth and spontaneous abortion among the three groups of patients. RESULTS: There were no statistically significant differences in the age, BMI and number of metaphase Ⅱ (MⅡ) oocytes among the three groups (P > 0.05). Sperm concentration and motility were dramatically higher (P < 0.01) while the rates of fertilization, clinical pregnancy and live birth remarkably lower in group A than in B and C (P < 0.01). No statistically significant difference was observed in the spontaneous abortion rate among the three groups (P > 0.05). CONCLUSION: ICSI can achieve relatively satisfactory outcomes of clinical pregnancy in patients with ASS or MMAF, but only a low fertilization rate or no fertilization at all in those with globozoospermia even if treated by artificial oocyte activation.

Mutations in PMFBP1 Cause Acephalic Spermatozoa Syndrome.

Acephalic spermatozoa syndrome is a severe teratozoospermia that leads to male infertility. Our previous work showed that biallelic SUN5 mutations are responsible for acephalic spermatozoa syndrome in about half of affected individuals, while pathogenic mechanisms in the other individuals remain to be elucidated. Here, we identified a homozygous nonsense mutation in the testis-specific gene PMFBP1 using whole-exome sequencing in a consanguineous family with two infertile brothers with acephalic spermatozoa syndrome. Sanger sequencing of PMFBP1 in ten additional infertile men with acephalic spermatozoa syndrome and without SUN5 mutations revealed two homozygous variants and one compound heterozygous variant. The disruption of Pmfbp1 in male mice led to infertility due to the production of acephalic spermatozoa and the disruption of PMFBP1's cooperation with SUN5 and SPATA6, which plays a role in connecting sperm head to the tail. PMFBP1 mutation-associated male infertility could be successfully overcome by intracytoplasmic sperm injection (ICSI) in both mouse and human. Thus, mutations in PMFBP1 are an important cause of infertility in men with acephalic spermatozoa syndrome.

Pathogenesis of acephalic spermatozoa syndrome caused by SUN5 variant.

Acephalic spermatozoa syndrome (ASS) is a rare teratozoospermia that leads to male infertility. Previous work suggested a genetic origin. Variants of Sad1 and UNC84 domain containing 5 (SUN5) are the main genetic cause of ASS; however, its pathogenesis remains unclear. Here, we performed whole-exome sequencing in 10 unrelated ASS and identified 2 homozygous variants, c.381delA[p.V128Sfs7*] and c.675C>A[p.Y225X], and 1 compound variant, c.88 C > T[p.R30X] and c.381 delA [p.V128Sfs7*], in SUN5 in 4 patients. The c.381delA variant had been identified as pathogenic in previous reports, while c.675C>A and c.88 C > T were two novel variants which could lead to a premature termination codon (PTC) and resulted in loss of SUN5, and may also be pathogenic. SUN5 mRNA and protein were present at very low levels in ASS patients with SUN5 nonsense mutation. Furthermore, the distribution of outer dense fiber protein 1 (ODF1) and Nesprin3 was altered in sperm of ASS patients with SUN5 variants. The co-immunoprecipitation analysis indicated that SUN5 and ODF1, SUN5 and Nesprin3, and ODF1 and Nesprin3 interacted with each other in transfected HEK293T cells. Thus, we propose that SUN5, Nesprin3, and ODF1 may form a 'triplet' structure through interactions at neck of sperm. When gene variants resulted in a loss of SUN5, the 'triplet' structure disappears and then the head-tail junction becomes fragile, leading to the occurrence of ASS.

Patients with acephalic spermatozoa syndrome linked to novel TSGA10/PMFBP1 variants have favorable pregnancy outcomes from intracytoplasmic sperm injection.

Acephalic spermatozoa syndrome is a rare form of teratozoospermia characterized by headless spermatozoa. Previous studies have found that variants in SUN5, PMFBP1, TSGA10, BRDT, and SPATC1L are associated with this phenotype. Many researchers have suggested that variants in TSGA10 without a proximal centriole might influence early embryonic development. This retrospective cohort study included 12 infertile men with severe acephalic spermatozoa in China. We identified six heterozygous variants and four homozygous variants in TSGA10/PMFBP1 in seven patients by whole-exome sequencing (WES). Acephalic spermatozoa defects due to different genetic variations may affect only spermatozoa morphology but do not reduce the chances of fertilization, affect embryo quality at early stages or impair intracytoplasmic sperm injection (ICSI) outcomes. Patients with TSGA10/PMFBP1 variations were all expected to have good prognoses with ICSI.

A novel homozygous missense mutation of PMFBP1 causes acephalic spermatozoa syndrome.

PURPOSE: To identify the pathogenic mutation in PMFBP1 leading to acephalic spermatozoa syndrome. METHODS: Sanger sequencing was used to screen for mutations in the known pathogenic genes SUN5 and PMFBP1 in a patient with acephalic spermatozoa syndrome. Western blotting and immunofluorescence were used to detect the expression and localization of PMFBP1 in sperm. At the same time, a PMFBP1 mutant was constructed, and the expression level of PMFBP1 protein was further verified by in vitro experiments. RESULTS: We identified a novel homozygous PMFBP1 missense mutation, c.301A>C (p.T101P), in an infertile male from a consanguineous family. Our results showed that the expression of PMFBP1 mutant protein was decreased obviously in sperm of the patient. CONCLUSION: Our results showed that the novel homozygous missense mutation of PMFBP1 may be a cause of acephalic spermatozoa syndrome, which provided a basis for genetic counseling for the patient.

Pathogenesis of acephalic spermatozoa syndrome caused by splicing mutation and de novo deletion in TSGA10.

PURPOSE: To identify the genetic causes for acephalic spermatozoa syndrome. METHODS: Whole-exome sequencing was performed on the proband from a non-consanguineous to identify pathogenic mutations for acephalic spermatozoa syndrome. Quantitative real-time polymerase chain reaction and whole genome sequencing were subjected to detect deletion. The functional effect of the identified splicing mutation was investigated by minigene assay. Western blot and immunofluorescence were performed to detect the expression level and localization of mutant TSGA10 protein. RESULTS: Here, we identified a novel heterozygous splicing mutation in TSGA10 (NM_025244: c.1108-1G > T), while we confirmed that there was a de novo large deletion in the proband. The splicing mutation led to the skipping of the exon15 of TSGA10, which resulted in a truncated protein (p. A370Efs*293). Therefore, we speculated that the splicing mutation might affect transcription and translation without the dosage compensation of a normal allele, which possesses a large deletion including intact TSGA10. Western blot and immunofluorescence demonstrated that the very low expression level of truncated TSGA10 protein led the proband to present the acephalic spermatozoa phenotype. CONCLUSION: Our finding expands the spectrum of pathogenic TSGA10 mutations that are responsible for ASS and male infertility. It is also important to remind us of paying attention to the compound heterozygous deletion in patients from non-consanguineous families, so that we can provide more precise genetic counseling for patients.

Genetic basis of acephalic spermatozoa syndrome, and intracytoplasmic sperm injection outcomes in infertile men: a systematic scoping review.

PURPOSE: Acephalic spermatozoa syndrome (ASS) is known as a severe type of teratozoospermia, defined as semen composed of mostly headless spermatozoa that affect male fertility. In this regard, this systematic review aimed to discuss gene variants associated with acephalic spermatozoa phenotype as well as the clinical outcomes of intracytoplasmic sperm injection (ICSI) treatment for the acephalic spermatozoa-associated male infertility. METHODS: A systematic search was performed on PubMed, Embase, Scopus, and Ovid databases until May 17, 2020. This systematic scoping review was reported in terms of the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) statement. RESULTS: Twenty articles were included in this systematic review. Whole-exome and Sanger sequencing have helped in the identification of variants in SUN5, PMFBP1, BRDT, TSGA10, DNAH6, HOOK1, and CEP112 genes as possible causes of this phenotype in humans. The results of the ICSI are conflicting due to both positive and negative reports of ICSI outcomes. CONCLUSION: ASS has a genetic origin, and several genetic alterations related to the pathogenesis of this anomaly have been recently identified. Notably, only SUN5 and PMFBP1 mutations are well-known to be implicated in ASS. Accordingly, more functional studies are needed to confirm the pathogenicity of other variants. ICSI could provide a promising treatment for acephalic spermatozoa-associated male infertility. Besides the importance of sperm head-tail junction integrity, some other factors, whether within the sperm cell or female factors, may be involved in the ICSI outcome.

Identification and Characterization of the Most Common Genetic Variant Responsible for Acephalic Spermatozoa Syndrome in Men Originating from North Africa.

Acephalic spermatozoa syndrome (ASS) is a rare but extremely severe type of teratozoospermia, defined by the presence of a majority of headless flagella and a minority of tail-less sperm heads in the ejaculate. Like the other severe monomorphic teratozoospermias, ASS has a strong genetic basis and is most often caused by bi-allelic variants in SUN5 (Sad1 and UNC84 domain-containing 5). Using whole exome sequencing (WES), we investigated a cohort of nine infertile subjects displaying ASS. These subjects were recruited in three centers located in France and Tunisia, but all originated from North Africa. Sperm from subjects carrying candidate genetic variants were subjected to immunofluorescence analysis and transmission electron microscopy. Moreover, fluorescent in situ hybridization (FISH) was performed on sperm nuclei to assess their chromosomal content. Variant filtering permitted us to identify the same SUN5 homozygous frameshift variant (c.211+1_211+2dup) in 7/9 individuals (78%). SUN5 encodes a protein localized on the posterior part of the nuclear envelope that is necessary for the attachment of the tail to the sperm head. Immunofluorescence assays performed on sperm cells from three mutated subjects revealed a total absence of SUN5, thus demonstrating the deleterious impact of the identified variant on protein expression. Transmission electron microscopy showed a conserved flagellar structure and a slightly decondensed chromatin. FISH did not highlight a higher rate of chromosome aneuploidy in spermatozoa from SUN5 patients compared to controls, indicating that intra-cytoplasmic sperm injection (ICSI) can be proposed for patients carrying the c.211+1_211+2dup variant. These results suggest that the identified SUN5 variant is the main cause of ASS in the North African population. Consequently, a simple and inexpensive genotyping of the 211+1_211+2dup variant could be beneficial for affected men of North African origin before resorting to more exhaustive genetic analyses.

[Genetic analysis of three cases of acephalic spermatozoa syndrome caused by SUN5 mutation and the outcome of assisted reproductive technology].

To explore the genetic causes of 3 male infertility patients with acephalospermia and the outcome of assisted reproductive technology. Clinical diagnosis, sperm morphology examination, sperm transmission electron microscopy examination were performed on 3 patients, and the whole exome sequencing technology was used for screening, Sanger sequencing verification, mutation pathogenicity analysis, and protein sequence homology comparison. Assisted reproductive technology was implemented to assist pregnancy treatment. The 3 patients were all sporadic infertile men, aged 25, 42 and 26 years, and there was no obvious abnormality in the general physical examination. Male external genitalia developed normally, bilateral testicles were normal in volume, and bilateral epididymis and spermatic vein were palpated without nodules, cysts, and tenderness. Repeated semen analysis showed that a large number of immature sperm could be seen, and they had the ability to move. The SUN5 gene of the 3 male infertile patients was a case of homozygous missense mutation c.7C>T (p.Arg3Trp), a case of compound heterozygous missense mutation c.1067G>A (p.Arg356His) and nonsense mutation c.216G>A (p.Trp72*) and a case of homozygous missense mutation c.1043A>T (p.Asn348Ile), of which c.7C>T (p.Arg3Trp) and c.1067G>A (p.Arg356His) were new variants that had not been reported. SIFT, Mutation Taster and PolyPhen-2 software function prediction results were all harmful, the nonsense mutation c.216G>A (p.Trp72*) led to the premature termination of peptide chain synthesis which might have a greater impact on protein function. The homology regions in the protein sequence homology alignment were all highly conserved.The 3 male patients and their spouses obtained 4 biological offspring through intracytoplasmic sperm injection, all of which were boys, and one of them was a twin.Three male infertile patients might be caused by SUN5 gene mutations. Such patients could obtain their biological offspring through assisted reproductive technology. It was still necessary to pay attention to the genetic risk of ASS, it was recommended that both men and women conduct genetic counseling and screening at the same time. In clinical diagnosis, whole exome sequencing technology could be used to perform auxiliary examinations to determine the treatment plan and assisted reproductive methods as soon as possible to reduce the burden on the family and society. The newly discovered mutation sites of SUN5 gene provided clues and directions for elucidating the pathogenic mechanism, and at the same time expanded the pathogenic mutation spectrum of ASS.

The coupling apparatus of the sperm head and tail†.

A strong sperm head-tail coupling apparatus (HTCA) is needed to ensure the integrity of spermatozoa during their fierce competition to fertilize the egg. A lot of HTCA-specific components have evolved to strengthen the attachment of the tail to the implantation fossa at the sperm head. Defects in HTCA formation lead to acephalic spermatozoa syndrome and pathologies of some male infertility. Recent studies have provided insights into the pathogenic molecular mechanisms of acephalic spermatozoa syndrome. Here, we summarize the proteins involved in sperm neck development and focus on their roles in the formation of HTCA. In addition, we discuss the fine structures of the sperm neck in different species from an evolutionary view, highlighting the potential conservative mechanism of HTCA formation.

Loss-of-function mutations in centrosomal protein 112 is associated with human acephalic spermatozoa phenotype.

Acephalic spermatozoa, characterized by the headless sperm in the ejaculate, is a rare type of teratozoospermia. Here, we recruited two infertile patients with an acephalic spermatozoa phenotype to investigate the genetic pathology of acephalic spermatozoa. Whole-exome sequencing analysis was performed and found mutations in CEP112 in the two patients: homozygous mutation c.496C > T:p.(Arg166X) in exon 5 from P1; and the biallelic mutations c.2074C > T:p.(Arg692Trp) in exon 20 and c.2104C > T:p.(Arg702Cys) in exon 20 from P2. Sanger sequencing confirmed the CEP112 mutations in the two patients. In silico analysis revealed that these CEP112 mutations are deleterious and rare, and all the mutations impact the coiled-coil domain of CEP112, which may affect the protein function. The c.496C > T:p.Arg166X resulted in a truncated CEP112, which was verified by the mutation expression plasmid. The CEP112 expression was significantly reduced in the P2, suggesting the biallelic mutations c.2074C > T and c.2104C > T may affect the function and stability of CEP112. Therefore, we speculate that the loss-of-function mutations in CEP112 may be account for the human acephalic spermatozoa phenotype.

[Outcomes of assisted reproductive technology for patients with different types of teratozoospermia].

OBJECTIVE: To discuss the outcomes of ICSI in infertile patients with globozoospermia (GS), acephalic spermatozoa syndrome (ASS) or teratozoospermia with miniacrosome and irregular-headed sperm defect (TMRHS). METHODS: This retrospective study included 3 cases of GS, 3 cases of ASS and 2 cases of TMRHS undergoing ICSI. We analyzed the rates of fertilization, cleavage, blastocyst formation, implantation, clinical pregnancy and live birth in the three groups of patients. RESULTS: The patients of the GS and ASS groups all achieved clinical pregnancies and healthy births, but those of the TMRHS group showed a lower fertilization rate than the other two groups and achieved no clinical pregnancy. CONCLUSIONS: ICSI could achieve successful clinical pregnancy in infertile patients with globozoospermia or acephalic spermatozoa syndrome, but no satisfactory clinical outcome in those with miniacrosome and irregular-headed sperm defect, though it has to be further proved by more studies with larger-sized samples.

Mechanistic insights into acephalic spermatozoa syndrome-associated mutations in the human SUN5 gene.

Acephalic spermatozoa syndrome has been reported for many decades; it is characterized by very few intact spermatozoa and tailless sperm heads in the semen and causes severe male infertility. The only gene in which mutations have been found to be associated with this syndrome encodes Sad1 and UNC84 domain-containing 5 (SUN5), a testis-specific nuclear envelope protein. The functional role of SUN5 has been well-studied in mouse models, but the molecular basis for the pathogenic effects of mutations in the human SUN5 gene remains elusive. Here, we report a new SUN5 mutation (c.475C→T; p.Arg159*), and explore the pathogenic effects of all known SUN5 mutations on acephalic spermatozoa syndrome. Using an artificial splicing system, we found that the intronic mutation affects the splicing of SUN5 mRNA, yielding a premature stop codon that results in a truncated SUN5 protein. We also found that SUN5 interacts with the coupling apparatus protein DnaJ heat shock protein family (Hsp40) member B13 (DNAJB13) during spermatogenesis, and the substitutions in the SUN5 SUN domain impair its interaction with DNAJB13. Furthermore, we observed that many SUN5 mutations affect the secondary structure of the protein and influence its folding and cellular localization. In summary, our findings indicate an interaction of SUN5 with DNAJB13 during spermatogenesis, provide mechanistic insights into the functional role of this interaction in sperm head-tail integration, and elucidate the molecular etiology of acephalic spermatozoa syndrome-associated SUN5 mutations.

Biallelic mutations in PMFBP1 cause acephalic spermatozoa.

The majority of men with defects in spermatogenesis remain undiagnosed. Acephalic spermatozoa is one of the diseases causing primary infertility. However, the causes underlying over half of affected cases remain unclear. Here, we report by whole-exome sequencing the identification of homozygous and compound heterozygous truncating mutations in PMFBP1 of two unrelated individuals with acephalic spermatozoa. PMFBP1 was highly and specifically expressed in human and mouse testis. Furthermore, immunofluorescence staining in sperm from a normal control showed that PMFBP1 localizes to the head-flagella junction region, and the absence of PMFBP1 was confirmed in patients harboring PMFBP1 mutations. In addition, we generated Pmfbp1 knock-out (KO) mice, which we found recapitulate the acephalic sperm phenotype. Label-free quantitative proteomic analysis of testicular sperm from Pmfbp1 KO and control mice showed 124 and 35 proteins, respectively, increased or decreased in sperm from KO mice compared to that found in control mice. Gene ontology analysis indicates that the biological process of Golgi vesicle transport was the most highly enriched in differentially expressed proteins, indicating process defects related to Golgi complex function may disturb formation of the head-neck junction. Collectively, our data indicate that PMFBP1 is necessary for sperm morphology in both humans and mice, and that biallelic truncating mutations in PMFBP1 cause acephalic spermatozoa.

[Advances in the molecular genetic studies of acephalic spermatozoa syndrome].

Acephalic spermatozoa syndrome (ASS) is characterized by a predominance of headless spermatozoa with abnormal head-tail junction in the ejaculate, which causes severe male infertility. The pathogenic mechanism of ASS remained unclarified for a long time until recent identification of the four ASS-associated genes SUN5, PMFBP1, TSGA10, and BRDT and their mutations due to the development of high-throughput sequencing technology. This review summarizes the advances in the genetic studies of ASS, focusing on its pathogenic molecular mechanisms, which provide an important basis for the molecular diagnosis of the disease as well as for assisted reproductive technology.

TSGA10 is a novel candidate gene associated with acephalic spermatozoa.

Acephalic spermatozoa is a rare teratozoospermia associated with male infertility. However, the pathogenesis of this disorder remains unclear. Here, we report a 27 years old infertile male from a consanguineous family, who presented with 99% headless sperm in his ejaculate. Electron microscopic and immunofluorescence analysis suggested breakage at the midpiece of the patient's sperm cells. Subsequent whole-exome sequencing analysis identified a homozygous deletion within TSGA10 (c.211delG; p.A71Hfs*12), which resulted in the production of truncated TSGA10 protein. TSGA10 is a testis-specific protein that localized to the midpiece in the spermatozoa of a normal control; however, immunostaining failed to detect TSGA10 protein in the patient's sperm. Western blot analysis also showed complete absence of TSGA10 protein in the patient. One cycle of in vitro fertilization-assisted reproduction was conducted, but pregnancy was not achieved after embryo transfer, possibly due to poor embryo quality. Therefore, we speculate that the presence of rare sequence variants within TSGA10 may be associated with acephalic spermatozoa in humans.

DNAH6 is a novel candidate gene associated with sperm head anomaly.

Globozoospermia and acephalic spermatozoa are two rare sperm head anomalies associated with male infertility. Combination of the two phenotypes in the same patient is extremely rare, so the underlying pathogenesis of this disorder remains unclear. Here, we report a 35-year-old infertile male, who presented with 30% of sperm-lacked heads and 69% of sperm round-headed or small-headed with neck thickening in his ejaculate. Subsequent whole-exome sequencing (WES) analysis identified compound heterozygous variants within the DNAH6 gene. DNAH6 is a testis-specific-expressed protein that was localised to the neck region in the spermatozoa of normal control; however, immunofluorescent staining failed to detect DNAH6 protein in the patient's spermatozoa. Quantitative real-time PCR analysis also showed the complete absence of DNAH6 mRNA in the patient's spermatozoa. Moreover, two cycles of in vitro fertilisation (IVF)-assisted reproduction were carried out, but pregnancy was not achieved after embryo transfer. Therefore, rare sequence variants in DNAH6 might be susceptibility risks for human sperm head anomaly.

A novel homozygous TSGA10 missense variant causes acephalic spermatozoa syndrome in a Pakistani family.

BACKGROUND: Acephalic spermatozoa syndrome is a rare type of teratozoospermia causing male infertility due to detachment of the sperm head and flagellum, which precludes fertilization potential. Although loss-of-function variations in several genes, including TSGA10, have been associated with acephalic spermatozoa syndrome, the genetic cause of many cases remains unclear. RESULTS: We recruited a Pakistani family with two infertile brothers who suffered from acephalic spermatozoa syndrome. Through whole-exome sequencing (WES) followed by Sanger sequencing, we identified a novel missense variant in TSGA10 (c.1112T > C, p. Leu371Pro), which recessively co-segregated with the acephalic spermatozoa syndrome within this family. Ultrastructural analyses of spermatozoa from the patient revealed that 98% of flagellar cross-sections displayed abnormal axonemal ultrastructure, in addition to the head-flagellum detachment. Real-time quantitative PCR analysis revealed almost no detectable TSAG10 mRNA and western blot analysis also failed to detect TSAG10 protein in patient's sperm samples while TSGA10 expression was clearly detected in control samples. Consistently, immunofluorescence analysis demonstrated the presence of TSGA10 signal in the midpiece of sperm from the control but a complete absence of TSGA10 signal in sperm from the patient. CONCLUSION: Altogether, our study identifies a novel TSGA10 pathogenic variant as a cause of acephalic spermatozoa syndrome in this family and provides information regarding the clinical manifestations associated with TSGA10 variants in human.

RéSUMé: CONTEXTE: Le syndrome des spermatozoïdes acéphaliques est un type rare de tératozoospermie provoquant une infertilité masculine en raison du détachement de la tête et du flagelle des spermatozoïdes, ce qui exclut une potentielle fécondation. Bien que des variations de perte de fonction dans plusieurs gènes, y compris TSGA10, aient été associées au syndrome des spermatozoïdes acéphaliques, la cause génétique de nombreux cas reste incertaine. RéSULTATS: Nous avons recruté une famille pakistanaise avec deux frères infertiles qui souffraient du syndrome des spermatozoïdes acéphaliques. Grâce au séquençage de l'exome entier (WES) suivi du séquençage Sanger, nous avons identifié un nouveau variant faux-sens dans TSGA10 (c.1112T > C, p. Leu371Pro), qui co-ségréguait de manière récessive avec le syndrome des spermatozoïdes acéphaliques au sein de cette famille. Les analyses ultrastructurales des spermatozoïdes des patients ont révélé que 98% des coupes transversales flagellaires présentaient une ultrastructure axonémiques anormales, en plus du décollement tête-flagelle. L'analyse quantitative par PCR en temps réel n'a révélé presque aucun ARNm TSAG10 détectable; l'analyse par transfert Western n'a pas non plus réussi à détecter la protéine TSAG10 dans les échantillons de sperme des patients, tandis que l'expression de TSGA10 a été clairement détectée dans les échantillons du témoin. De manière cohérente, l'analyse par immunofluorescence a démontré la présence du signal TSGA10 dans la partie médiane des spermatozoïdes du témoin, mais une absence totale de signal TSGA10 chez ceux des patients. CONCLUSION: Dans l'ensemble, notre étude identifie un nouveau variant pathogène de TSGA10 comme cause du syndrome des spermatozoïdes acéphaliques dans cette famille et fournit des informations concernant les manifestations cliniques associées aux variants de TSGA10 chez l'homme. MOTS-CLéS: Infertilité, TSGA10, Spermatozoïdes acéphaliques, Variations faux-sens.

Novel mutations of PMFBP1 in a man with acephalic spermatozoa defects.

BACKGROUND: Acephalic spermatozoa (AS) is a serious but rare reproductive genetic disorder that causes infertility in men. To date, only a few genes associated with AS defects have been identified, including the polyamine modulated factor 1 binding protein 1 (PMFBP1) gene. Consistent with this, PMFBP1 localizes to the head-neck connection, which bridges the implantation fossa and basal body. METHODS: A male patient was diagnosed as having an AS defect. Blood samples from all family members and a sample of the patient's semen were collected to determine the genetic causes of his infertility. RESULTS: Compound heterozygote mutation in the PMFBP1 gene, which is associated with AS defects in the present case: two loss-of-function mutations, with one a nonsense mutation c.361C > T p.Gln121Ter, and another a splice donor mutation c.414 + 1G > T. The current study, together with previous studies, suggests that the nonsense mutation is responsible for a truncated PMFBP1 protein during its formation; a splice donor mutation c.414 + 1G > T might lead to new open reading frames, from which the dysfunction of an abnormal PMFBP1 protein might be predicted. Additionally, the expression of outer dense fiber 1 (ODF1) and ODF2 proteins has been experimentally shown to be regulated by the truncated PMFBP1 protein. CONCLUSION: We herein present a case with AS defects associated with heterozygote mutations of PMFBP1, which have been shown to be rare and pathogenic; the association with an AS defect is a monogenic disorder with a recessive inherited pattern in the patient's family.