Comorbid familial nonobstructive azoospermia (NOA) and congenital cataract (CC) have not been reported previously, and no single human gene has been associated with both diseases in humans. Our ...purpose was to uncover novel human mutations and genes causing familial NOA and CC.
We performed whole-exome sequencing for two brothers with both NOA and CC from a consanguineous family. Mutation screening of TDRD7 was performed in another similar consanguineous family and 176 patients with azoospermia or CC alone and 520 healthy controls. Histological analysis was performed for the biopsied testicle sample in one patient, and knockout mice were constructed to verify the phenotype of the mutation in TDRD7.
Two novel loss-of-function mutations (c.324_325insA (T110Nfs*30) and c.688_689insA (p.Y230X), respectively) of TDRD7 were found in the affected patients from the two unrelated consanguineous families. Histological analysis demonstrated a lack of mature sperm in the male patient's seminiferous tubules. The mutations were not detected in patients with CC or NOA alone. Mice with Tdrd7 gene disrupted at a similar position precisely replicated the human syndrome.
We identified TDRD7 causing CC as a new pathogenic gene for male azoospermia in human, with an autosomal recessive mode of inheritance.
The syndrome of multiple morphological abnormalities of the sperm flagella (MMAF) is a specific kind of asthenoteratozoospermia with a mosaic of flagellar morphological abnormalities (absent, short, ...bent, coiled, and irregular flagella). MMAF was proposed in 2014 and has attracted increasing attention; however, it has not been clearly understood. In this review, we elucidate the definition of MMAF from a systematical view, the difference between MMAF and other conditions with asthenoteratozoospermia or asthenozoospermia (such as primary mitochondrial sheath defects and primary ciliary dyskinesia), the knowledge regarding its etiological mechanism and related genetic findings, and the clinical significance of MMAF for intracytoplasmic sperm injection and genetic counseling. This review provides the basic knowledge for MMAF and puts forward some suggestions for further investigations.
Severe asthenozoospermia is a common cause of male infertility. Recent studies have revealed that
SPEF2
mutations lead to multiple morphological abnormalities of the sperm flagella (MMAF) without ...primary ciliary dyskinesia (PCD) symptoms in males, but PCD phenotype was also found in one female individual. Therefore, whether there is a phenotypic continuum ranging from infertile patients with PCD to MMAF patients with no or low noise PCD manifestations remains elusive. Here, we performed whole-exome sequencing in 47 patients with severe asthenozoospermia from 45 unrelated Chinese families. We identified four novel biallelic mutations in
SPEF2
(8.9%, 4/45) in six affected individuals (12.8%, 6/47), while no deleterious biallelic variants in
SPEF2
were detected in 637 controls, including 219 with oligoasthenospermia, 195 with non-obstructive azoospermia, and 223 fertile controls. Notably, all six patients exhibited PCD-like symptoms, including recurrent airway infections, bronchitis, and rhinosinusitis. Ultrastructural analysis revealed normal 9 + 2 axonemes of respiratory cilia but consistently abnormal 9 + 0 axoneme or disordered accessory structures of sperm flagella, indicating different roles of SPEF2 in sperm flagella and respiratory cilia. Subsequently, a
Spef2
knockout mouse model was used to validate the PCD-like phenotype and male infertility, where the subfertility of female
Spef2
−/−
mice was found unexpectedly. Overall, our data bridge the link between MMAF and PCD based on the association of
SPEF2
mutations with both infertility and PCD in males and provide basis for further exploring the molecular mechanism of SPEF2 during spermiogenesis and ciliogenesis.
Male infertility due to spermatogenesis defects affects millions of men worldwide. However, the genetic etiology of the vast majority remains unclear. Here we describe three men with primary ...infertility due to multiple morphological abnormalities of the sperm flagella (MMAF) from two unrelated Han Chinese families. We performed whole-exome sequencing (WES) and Sanger sequencing on the proband of family 1, and found that he carried novel compound heterozygous missense mutations in dynein axonemal heavy chain 6 (DNAH6) that resulted in the substitution of a conserved amino acid residue and co-segregated with the MMAF phenotype in this family. Papanicolaou staining and transmission electron microscopy analysis revealed morphological and ultrastructural abnormalities in the sperm flagella in carriers of these genetic variants. Immunostaining experiments showed that DNAH6 was localized in the sperm tail. This is the first report identifying novel recessive mutations in DNAH6 as a cause of MMAF. These findings expand the spectrum of known MMAF mutations and phenotypes and provide information that can be useful for genetic and reproductive counseling of MMAF patients.
(A) Characteristics of spermatozoa in asthenoteratozoospermia affected man. (B) Pedigree and Sanger sequencing analysis of the family. (C) The effect of the missense variant in the CCIN gene.
Oligoasthenoteratozoospermia (OAT) is a common type of male infertility; however, its genetic causes remain largely unknown. Some of the genetic determinants of OAT are gene defects affecting ...spermatogenesis. BCORL1 (BCL6 corepressor like 1) is a transcriptional corepressor that exhibits the OAT phenotype in a knockout mouse model. A hemizygous missense variant of BCORL1 (c.2615T > G:p.Val872Gly) was reported in an infertile male patient with non‐obstructive azoospermia (NOA). Nevertheless, the correlation between BCORL1 variants and OAT in humans remains unknown. In this study, we used whole‐exome sequencing to identify a novel hemizygous nonsense variant of BCORL1 (c.1564G > T:p.Glu522*) in a male patient with OAT from a Han Chinese family. Functional analysis showed that the variant produced a truncated protein with altered cellular localization and a dysfunctional interaction with SKP1 (S‐phase kinase‐associated protein 1). Further population screening identified four BCORL1 missense variants in subjects with both OAT (1 of 325, 0.31%) and NOA (4 of 355, 1.13%), but no pathogenic BCORL1 variants among 362 fertile subjects. In conclusion, our findings indicate that BCORL1 is a potential candidate gene in the pathogenesis of OAT and NOA, expanded its disease spectrum and suggested that BCORL1 may play a role in spermatogenesis by interacting with SKP1.
The nonsense variant of BCORL1 damaged the normal interaction between BCORL1 and SKP1, thereby resulted in impaired spermatogenesis.
Severe oligozoospermia (SO) is an important cause of male infertility. Its etiology and pathogenesis are associated with genetic abnormalities; however, the genetic causes of the majority of ...idiopathic human SO remain unclear. Here, we report a homozygous splice‐site mutation in M1AP (meiosis 1 associated protein; NM_138804, c.1435‐1G>A) observed in a patient with SO from a consanguineous Han Chinese family. His parents and fertile brother were heterozygous for the mutation. The splice variant led to a lack of M1AP protein in the patient's spermatozoa. Ultrastructural and immunostaining analyses of patient's spermatozoa showed highly aberrant swollen mitochondrial sheaths with normal axonemal structures. Subsequent mutation screening identified three additional heterozygous M1AP variants in 4/243 subjects with idiopathic SO, but no M1AP variants among 223 fertile subjects. Additionally, a previously study reported that M1ap knock‐out mice exhibited SO due to meiotic arrest. Hence, our findings indicate that M1AP mutation might represent novel genetic alteration responsible for human SO.
(A) Pedigree and Sanger sequencing analysis of the family. (B) The effect of the splice‐split variant in the M1AP gene. (C) Aberrant swollen mitochondrial sheath in sperm flagella of M1AP mutant spermatozoa.
Abstract
Background
Previous studies suggested that non-invasive preimplantation genetic testing (niPGT) for intracytoplasmic sperm injection (ICSI) blastocysts can be used to identify chromosomal ...ploidy and chromosomal abnormalities. Here, we report the feasibility and performance of niPGT for conventional in vitro fertilization (IVF) blastocysts.
Methods
This was a prospective observational study. In the preclinical stage, whole genome amplification and NGS were performed using the sperm spent culture medium (SCM). Then, trophectoderm (TE) biopsies and corresponding SCM derived from 27 conventional IVF monopronuclear embryos were collected. In the clinical stage, samples from 25 conventional IVF cycles and 37 ICSI cycles from April 2020–August 2021 were collected for performance evaluation.
Results
Preclinically, we confirmed failed sperm DNA amplification under the current amplification system. Subsequent niPGT from the 27 monopronuclear blastocysts showed 69.2% concordance with PGT results of corresponding TE biopsies. In the clinical stage, no paternal contamination was observed in any of the 161 SCM samples from conventional IVF. While maternal contamination was observed in 29.8% (48/161) SCM samples, only 2.5% (4/161) samples had a contamination ratio ≥ 50%. Compared with that of TE biopsy, the performances of NiPGT from 161 conventional IVF embryos and 122 ICSI embryos were not significantly different (P > 0.05), with ploidy concordance rates of 75% and 74.6% for IVF and ICSI methods, respectively. Finally, evaluation of the euploid probability of embryos with different types of niPGT results showed prediction probabilities of 82.8%, 77.8%, 62.5%, 50.0%, 40.9% and 18.4% for euploidy, sex-chromosome mosaics only, low-level mosaics, multiple abnormal chromosomes, high-level mosaics and aneuploidy, respectively.
Conclusions
Our research results preliminarily confirm that the niPGT approach using SCM from conventional IVF has comparable performance with ICSI and might broadening the application scope of niPGT.
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