ABSTRACT
The transcription factor WT1 plays a critical role in several embryonic developmental processes such as gonadogenesis, nephrogenesis, and cardiac development. We generated a homozygous (MCRIi031-A-3) WT1 knockout induced pluripotent stem cell (iPSC) line from human fibroblasts using a one-step protocol for CRISPR/Cas9 gene-editing and episomal-based reprogramming. The cells exhibit a normal karyotype and morphology, express pluripotency markers, and have the capacity to differentiate into the three embryonic germ layers. These cell lines will allow us to further explore the role of WT1 in critical developmental processes.
Subject(s)
Homozygote , Induced Pluripotent Stem Cells , WT1 Proteins , Humans , Induced Pluripotent Stem Cells/metabolism , Induced Pluripotent Stem Cells/cytology , WT1 Proteins/genetics , WT1 Proteins/metabolism , Cell Line , CRISPR-Cas Systems , Cell Differentiation , Gene Knockout Techniques , Gene EditingABSTRACT
The transcription factor SOX9 plays a critical role in several embryonic developmental processes such as gonadogenesis, chrondrogenesis, and cardiac development. We generated heterozygous (MCRIi031-A-1) and homozygous (MCRIi031-A-2) SOX9 knockout induced pluripotent stem cell (iPSC) lines from human fibroblasts using a one-step protocol for CRISPR/Cas9 gene-editing and episomal-based reprogramming. Both iPSC lines exhibit a normal karyotype and morphology, express pluripotency markers, and have the capacity to differentiate into the three embryonic germ layers. These cell lines will allow us to further explore the role of SOX9 in critical developmental processes.
Subject(s)
Heterozygote , Homozygote , Induced Pluripotent Stem Cells , SOX9 Transcription Factor , Humans , Induced Pluripotent Stem Cells/metabolism , Induced Pluripotent Stem Cells/cytology , SOX9 Transcription Factor/metabolism , SOX9 Transcription Factor/genetics , Cell Line , CRISPR-Cas Systems , Gene Knockout Techniques , Gene Editing , Cell DifferentiationABSTRACT
Premature ovarian insufficiency is a common form of female infertility affecting up to 4% of women and characterised by amenorrhea with elevated gonadotropin before the age of 40. Oocytes require controlled DNA breakage and repair for homologous recombination and the maintenance of oocyte integrity. Biallelic disruption of the DNA damage repair gene, Fanconi anemia complementation group A (FANCA), is a common cause of Fanconi anaemia, a syndrome characterised by bone marrow failure, cancer predisposition, physical anomalies and POI. There is ongoing dispute about the role of heterozygous FANCA variants in POI pathogenesis, with insufficient evidence supporting causation. Here, we have identified biallelic FANCA variants in French sisters presenting with POI, including a novel missense variant of uncertain significance and a likely pathogenic deletion that initially evaded detection. Functional studies indicated no discernible effect on DNA damage sensitivity in patient lymphoblasts. These novel FANCA variants add evidence that heterozygous loss of one allele is insufficient to cause DNA damage sensitivity and POI. We propose that intragenic deletions, that are relatively common in FANCA, may be missed without careful analysis, and could explain the presumed causation of heterozygous variants. Accurate variant curation is critical to optimise patient care and outcomes.
Subject(s)
Alleles , Fanconi Anemia Complementation Group A Protein , Primary Ovarian Insufficiency , Humans , Primary Ovarian Insufficiency/genetics , Female , Fanconi Anemia Complementation Group A Protein/genetics , Adult , Fanconi Anemia/genetics , Fanconi Anemia/diagnosis , Siblings , Heterozygote , Genetic Predisposition to Disease , Pedigree , Mutation/geneticsABSTRACT
The NR2F2 gene encodes the transcription factor COUP-TFII, which is upregulated in embryonic mesoderm. Heterozygous variants in NR2F2 cause a spectrum of congenital anomalies including cardiac and gonadal phenotypes. We generated heterozygous (MCRIi030-A-1) and homozygous (MCRIi030-A-2) NR2F2-knockout induced pluripotent stem cell (iPSC) lines from human fibroblasts using a one-step protocol for CRISPR/Cas9 gene-editing and episomal-based reprogramming. Both iPSC lines exhibited a normal karyotype, typical pluripotent cell morphology, pluripotency marker expression, and the capacity to differentiate into the three embryonic germ layers. These lines will allow us to explore the role of NR2F2 during development and disease.
Subject(s)
Induced Pluripotent Stem Cells , Humans , Induced Pluripotent Stem Cells/metabolism , Heart , Heterozygote , Homozygote , Phenotype , CRISPR-Cas Systems/genetics , COUP Transcription Factor II/genetics , COUP Transcription Factor II/metabolismABSTRACT
RESEARCH QUESTION: Premature ovarian insufficiency (POI) is characterised by amenorrhea associated with elevated follicle stimulating hormone (FSH) under the age of 40 years and affects 1-3.7% women. Genetic factors explain 20-30% of POI cases, but most causes remain unknown despite genomic advancements. DESIGN: We used whole exome sequencing (WES) in four Iranian families, validated variants via Sanger sequencing, and conducted the Acyl-cLIP assay to measure HHAT enzyme activity. RESULTS: Despite ethnic homogeneity, WES revealed diverse genetic causes, including a novel homozygous nonsense variant in SYCP2L, impacting synaptonemal complex (SC) assembly, in the first family. Interestingly, the second family had two independent causes for amenorrhea - the mother had POI due to a novel homozygous loss-of-function variant in FANCM (required for chromosomal stability) and her daughter had primary amenorrhea due to a novel homozygous GNRHR (required for gonadotropic signalling) frameshift variant. WES analysis also provided cytogenetic insights. WES revealed one individual was in fact 46, XY and had a novel homozygous missense variant of uncertain significance in HHAT, potentially responsible for complete sex reversal although functional assays did not support impaired HHAT activity. In the remaining individual, WES indicated likely mosaic Turners with the majority of X chromosome variants having an allelic balance of â¼85% or â¼15%. Microarray validated the individual had 90% 45,XO. CONCLUSIONS: This study demonstrates the diverse causes of amenorrhea in a small, isolated ethnic cohort highlighting how a genetic cause in one individual may not clarify familial cases. We propose that, in time, genomic sequencing may become a single universal test required for the diagnosis of infertility conditions such as POI.
Subject(s)
Amenorrhea , Primary Ovarian Insufficiency , Humans , Female , Adult , Male , Amenorrhea/diagnosis , Amenorrhea/genetics , Iran , Primary Ovarian Insufficiency/genetics , Mutation, Missense , Genomics , DNA Helicases/geneticsABSTRACT
Disruption of meiosis and DNA repair genes is associated with female fertility disorders like premature ovarian insufficiency (POI). In this study, we identified a homozygous missense variant in the HELQ gene (c.596 A>C; p.Gln199Pro) through whole exome sequencing in a POI patient, a condition associated with disrupted ovarian function and female infertility. HELQ, an enzyme involved in DNA repair, plays a crucial role in repairing DNA cross-links and has been linked to germ cell maintenance, fertility, and tumour suppression in mice. To explore the potential association of the HELQ variant with POI, we used CRISPR/Cas9 to create a knock-in mouse model harbouring the equivalent of the human HELQ variant identified in the POI patient. Surprisingly, Helq knock-in mice showed no discernible phenotype, with fertility levels, histological features, and follicle development similar to wild-type mice. Despite the lack of observable effects in mice, the potential role of HELQ in human fertility, especially in the context of POI, should not be dismissed. Larger studies encompassing diverse ethnic populations and alternative functional approaches will be necessary to further examine the role of HELQ in POI. Our results underscore the potential uncertainties associated with genomic variants and the limitations of in vivo animal modelling.
Subject(s)
Infertility, Female , Primary Ovarian Insufficiency , Animals , Female , Humans , Mice , DNA Helicases/genetics , Homozygote , Infertility, Female/genetics , Mutation, Missense , Primary Ovarian Insufficiency/geneticsABSTRACT
Squamous cell carcinoma antigen recognized by T cells 3 (SART3) is an RNA-binding protein with numerous biological functions including recycling small nuclear RNAs to the spliceosome. Here, we identify recessive variants in SART3 in nine individuals presenting with intellectual disability, global developmental delay and a subset of brain anomalies, together with gonadal dysgenesis in 46,XY individuals. Knockdown of the Drosophila orthologue of SART3 reveals a conserved role in testicular and neuronal development. Human induced pluripotent stem cells carrying patient variants in SART3 show disruption to multiple signalling pathways, upregulation of spliceosome components and demonstrate aberrant gonadal and neuronal differentiation in vitro. Collectively, these findings suggest that bi-allelic SART3 variants underlie a spliceosomopathy which we tentatively propose be termed INDYGON syndrome (Intellectual disability, Neurodevelopmental defects and Developmental delay with 46,XY GONadal dysgenesis). Our findings will enable additional diagnoses and improved outcomes for individuals born with this condition.
Subject(s)
Gonadal Dysgenesis , Induced Pluripotent Stem Cells , Intellectual Disability , Male , Humans , Testis/metabolism , Induced Pluripotent Stem Cells/metabolism , RNA-Binding Proteins/genetics , RNA-Binding Proteins/metabolism , Antigens, NeoplasmABSTRACT
Premature ovarian insufficiency (POI) is a common cause of infertility in women, characterised by amenorrhea and elevated FSH under the age of 40 years. In some cases, POI is syndromic in association with other features such as sensorineural hearing loss in Perrault syndrome. POI is a heterogeneous disease with over 80 causative genes known so far; however, these explain only a minority of cases. Using whole-exome sequencing (WES), we identified a MRPL50 homozygous missense variant (c.335T > A; p.Val112Asp) shared by twin sisters presenting with POI, bilateral high-frequency sensorineural hearing loss, kidney and heart dysfunction. MRPL50 encodes a component of the large subunit of the mitochondrial ribosome. Using quantitative proteomics and western blot analysis on patient fibroblasts, we demonstrated a loss of MRPL50 protein and an associated destabilisation of the large subunit of the mitochondrial ribosome whilst the small subunit was preserved. The mitochondrial ribosome is responsible for the translation of subunits of the mitochondrial oxidative phosphorylation machinery, and we found patient fibroblasts have a mild but significant decrease in the abundance of mitochondrial complex I. These data support a biochemical phenotype associated with MRPL50 variants. We validated the association of MRPL50 with the clinical phenotype by knockdown/knockout of mRpL50 in Drosophila, which resulted abnormal ovarian development. In conclusion, we have shown that a MRPL50 missense variant destabilises the mitochondrial ribosome, leading to oxidative phosphorylation deficiency and syndromic POI, highlighting the importance of mitochondrial support in ovarian development and function.
Subject(s)
Gonadal Dysgenesis, 46,XX , Hearing Loss, Sensorineural , Primary Ovarian Insufficiency , Female , Humans , Gonadal Dysgenesis, 46,XX/genetics , Hearing Loss, Sensorineural/genetics , Mitochondria/genetics , Mutation, Missense , Primary Ovarian Insufficiency/genetics , Animals , Drosophila melanogasterABSTRACT
INTRODUCTION: Steroid 5-alpha reductase deficiency (5α-R2D) is a rare condition caused by genetic variants that reduce the activity of the enzyme that converts testosterone into dihydrotestosterone. The clinical spectrum of 5α-R2D is known to overlap with other 46,XY differences of sex development (DSD) such as androgen insensitivity or gonadal dysgenesis. However, the clinical trajectories of the aetiologies can differ, with 5α-R2D presenting its own challenges. METHODS: In this study, we have collated clinical information for five individuals with variants in SRD5A2 identified using research genetic testing in an Australian paediatric setting. RESULTS: We describe how a genetic finding resolved or confirmed a diagnosis for these individuals and how it guided clinical management and family counselling. CONCLUSION: This work highlights the importance of early genetic testing in children born with 46,XY DSD where it complements traditional first-line testing.
Subject(s)
Disorder of Sex Development, 46,XY , Genetic Testing , Male , Humans , Child , Mutation , Australia , 3-Oxo-5-alpha-Steroid 4-Dehydrogenase/genetics , Disorder of Sex Development, 46,XY/genetics , Disorder of Sex Development, 46,XY/pathology , Testosterone , Membrane Proteins/geneticsABSTRACT
46,XY gonadal dysgenesis (GD) is a Disorder/Difference of Sex Development (DSD) that can present with phenotypes ranging from ambiguous genitalia to complete male-to-female sex reversal. Around 50% of 46,XY DSD cases receive a molecular diagnosis. In mice, Fibroblast growth factor 9 (FGF9) is an important component of the male sex-determining pathway. Two FGF9 variants reported to date disrupt testis development in mice, but not in humans. Here, we describe a female patient with 46,XY GD harbouring the rare FGF9 variant (missense mutation), NM_002010.2:c.583G > A;p.(Asp195Asn) (D195N). By biochemical and cell-based approaches, the D195N variant disrupts FGF9 protein homodimerisation and FGF9-heparin-binding, and reduces both Sertoli cell proliferation and Wnt4 repression. XY Fgf9D195N/D195N foetal mice show a transient disruption of testicular cord development, while XY Fgf9D195N/- foetal mice show partial male-to-female gonadal sex reversal. In the general population, the D195N variant occurs at an allele frequency of 2.4 × 10-5 , suggesting an oligogenic basis for the patient's DSD. Exome analysis of the patient reveals several known and novel variants in genes expressed in human foetal Sertoli cells at the time of sex determination. Taken together, our results indicate that disruption of FGF9 homodimerization impairs testis determination in mice and, potentially, also in humans in combination with other variants.
Subject(s)
Fibroblast Growth Factor 9 , Gonadal Dysgenesis, 46,XY , Humans , Male , Female , Mice , Animals , Dimerization , Fibroblast Growth Factor 9/genetics , Testis , Gonads , Gonadal Dysgenesis, 46,XY/geneticsABSTRACT
The mitochondrial ribosome is critical to mitochondrial protein synthesis. Defects in both the large and small subunits of the mitochondrial ribosome can cause human disease, including, but not limited to, cardiomyopathy, hypoglycaemia, neurological dysfunction, sensorineural hearing loss and premature ovarian insufficiency (POI). POI is a common cause of infertility, characterised by elevated follicle-stimulating hormone and amenorrhea in women under the age of 40. Here we describe a patient with POI, sensorineural hearing loss and Hashimoto's disease. The co-occurrence of POI with sensorineural hearing loss indicates Perrault syndrome. Whole exome sequencing identified two compound heterozygous variants in mitochondrial ribosomal protein 7 (MRPS7), c.373A>T/p.(Lys125*) and c.536G>A/p.(Arg179His). Both novel variants are predicted to be pathogenic via in-silico algorithms. Variants in MRPS7 have been described only once in the literature and were identified in sisters, one of whom presented with congenital sensorineural hearing loss and POI, consistent with our patient phenotype. The other affected sister had a more severe disease course and died in early adolescence due to liver and renal failure before the reproductive phenotype was known. This second independent report validates that variants in MRPS7 are a cause of syndromic POI/Perrault syndrome. We present this case and review the current evidence supporting the integral role of the mitochondrial ribosome in supporting ovarian function.
Subject(s)
Gonadal Dysgenesis, 46,XX , Hearing Loss, Sensorineural , Primary Ovarian Insufficiency , Adolescent , Female , Humans , Mitochondrial Ribosomes/pathology , Gonadal Dysgenesis, 46,XX/genetics , Gonadal Dysgenesis, 46,XX/pathology , Primary Ovarian Insufficiency/genetics , Hearing Loss, Sensorineural/genetics , Hearing Loss, Sensorineural/pathology , Ribosomal Proteins/genetics , Mitochondrial Proteins/geneticsABSTRACT
CONTEXT: Premature ovarian insufficiency (POI) is a common form of female infertility that usually presents as an isolated condition but can be part of various genetic syndromes. Early diagnosis and treatment of POI can minimize comorbidity and improve health outcomes. OBJECTIVE: We aimed to determine the genetic cause of syndromic POI, intellectual disability, neutropenia, and cataracts. METHODS: We performed whole-exome sequencing (WES) followed by functional validation via RT-PCR, RNAseq, and quantitative proteomics, as well as clinical update of previously reported patients with variants in the caseinolytic peptidase B (CLPB) gene. RESULTS: We identified causative variants in CLPB, encoding a mitochondrial disaggregase. Variants in this gene are known to cause an autosomal recessive syndrome involving 3-methylglutaconic aciduria, neurological dysfunction, cataracts, and neutropenia that is often fatal in childhood; however, there is likely a reporting bias toward severe cases. Using RNAseq and quantitative proteomics we validated causation and gained insight into genotype:phenotype correlation. Clinical follow-up of patients with CLPB deficiency who survived to adulthood identified POI and infertility as a common postpubertal ailment. CONCLUSION: A novel splicing variant is associated with CLPB deficiency in an individual who survived to adulthood. POI is a common feature of postpubertal female individuals with CLPB deficiency. Patients with CLPB deficiency should be referred to pediatric gynecologists/endocrinologists for prompt POI diagnosis and hormone replacement therapy to minimize associated comorbidities.
Subject(s)
Cataract , Menopause, Premature , Neutropenia , Primary Ovarian Insufficiency , Female , Humans , Endopeptidase Clp/genetics , Endopeptidase Clp/metabolism , Transcriptome , Proteomics , Primary Ovarian Insufficiency/genetics , Phenotype , Cataract/geneticsABSTRACT
Premature ovarian insufficiency (POI) is a leading form of female infertility, characterised by menstrual disturbance and elevated follicle-stimulating hormone before age 40. It is highly heterogeneous with variants in over 80 genes potentially causative, but the majority of cases having no known cause. One gene implicated in POI pathology is TP63. TP63 encodes multiple p63 isoforms, one of which has been shown to have a role in the surveillance of genetic quality in oocytes. TP63 C-terminal truncation variants and N-terminal duplication have been described in association with POI, however, functional validation has been lacking. Here we identify three novel TP63 missense variants in women with nonsyndromic POI, including one in the N-terminal activation domain, one in the C-terminal inhibition domain, and one affecting a unique and poorly understood p63 isoform, TA*p63. Via blue-native page and luciferase reporter assays we demonstrate that two of these variants disrupt p63 dimerization, leading to constitutively active p63 tetramer that significantly increases the transcription of downstream targets. This is the first evidence that TP63 missense variants can cause isolated POI and provides mechanistic insight that TP63 variants cause POI due to constitutive p63 activation and accelerated oocyte loss in the absence of DNA damage.
Subject(s)
Primary Ovarian Insufficiency , Transcription Factors , Tumor Suppressor Proteins , Female , Humans , Mutation, Missense , Primary Ovarian Insufficiency/genetics , Transcription Factors/genetics , Tumor Suppressor Proteins/geneticsABSTRACT
Complete androgen insensitivity syndrome (CAIS), where 46,XY individuals present as female, is caused by variants in the androgen receptor gene (AR). We analyzed the DNA of a patient with suspected CAIS using a targeted gene sequencing panel and whole exome sequencing (WES) but did not detect any small nucleotide variants in AR. Analysis of WES data using our bioinformatics pipeline designed to detect copy number variations (CNV) uncovered a rare duplication of exon 2 of AR. Using array comparative genomic hybridization, the duplication was found to span 43.6 kb and is predicted to cause a frameshift and loss of AR protein. We confirmed the power of our WES-CNV detection protocol by identifying pathogenic CNVs in FSHR and NR5A1 in previously undiagnosed patients with disorders of sex development. Our findings illustrate the usefulness of CNV analysis in WES data to detect pathogenic genomic changes that may go undetected using only standard analysis protocols.
Subject(s)
Androgen-Insensitivity Syndrome , DNA Copy Number Variations , Androgen-Insensitivity Syndrome/genetics , Comparative Genomic Hybridization , DNA Copy Number Variations/genetics , Exome/genetics , Female , High-Throughput Nucleotide Sequencing/methods , Humans , Male , Exome Sequencing/methodsABSTRACT
Premature ovarian insufficiency (POI), affecting 1 in 100 women, is characterised by loss of ovarian function associated with elevated gonadotropin, before the age of 40. In addition to infertility, patients face increased risk of comorbidities such as heart disease, osteoporosis, cancer and/or early mortality. We used whole exome sequencing to identify the genetic cause of POI in seven women. Each had biallelic candidate variants in genes with a primary role in DNA damage repair and/or meiosis. This includes two genes, REC8 and HROB, not previously associated with autosomal recessive POI. REC8 encodes a component of the cohesin complex and HROB encodes a factor that recruits MCM8/9 for DNA damage repair. In silico analyses, combined with concordant mouse model phenotypes support these as new genetic causes of POI. We also identified novel variants in MCM8, NUP107, STAG3 and HFM1 and a known variant in POF1B. Our study highlights the pivotal role of meiosis in ovarian function. We identify novel variants, consolidate the pathogenicity of variants previously considered of unknown significance, and propose HROB and REC8 variants as new genetic causes while exploring their link to pathogenesis.
Subject(s)
Primary Ovarian Insufficiency , Animals , Cell Cycle Proteins/genetics , Chromosomes , DNA Helicases/genetics , DNA-Binding Proteins , Female , Humans , Meiosis/genetics , Mice , Phenotype , Primary Ovarian Insufficiency/genetics , Primary Ovarian Insufficiency/pathology , Exome SequencingABSTRACT
Background: Complete androgen insensitivity syndrome (CAIS) is a congenital condition caused by genetic defects in the androgen receptor (AR) gene located on the X chromosome, which lead to a phenotypical female individual with a 46, XY karyotype. Early diagnosis of CAIS is essential for proper clinical management, allows assessment of familial risk and contributes to healthcare decisions. However, diagnosis of CAIS can be overlooked in girls with inguinal hernia, resulting in inappropriate management. Methods: Five female patients from three unrelated families presented to our genetic clinic with primary amenorrhea. Each patient had been diagnosed with inguinal hernia in childhood and had undergone hernia repair without further investigation into what was contained in the hernial sac. We carried out physical examination, cytogenetic studies, hormonal evaluation, and molecular analysis to establish a comprehensive diagnosis. Family history and pedigree were collated to identify at-risk family members. Results: All patients presented with female external genitalia. Cytogenetic studies revealed a 46, XY karyotype and hormonal analysis suggested a diagnosis of CAIS. Sequencing of the AR gene in all patients and suspected family members revealed pathogenic variants in the AR gene and confirmed the molecular diagnosis of CAIS. Conclusions: We report the delayed diagnosis of CAIS in female Indonesian patients with a history of inguinal hernia in childhood. An early diagnosis of CAIS is essential for appropriate clinical management, as well as assessing familial risk. Increasing awareness among clinicians is paramount, and we encourage a CAIS diagnosis to be considered in any patient presenting with female appearance and inguinal hernia.
Subject(s)
Androgen-Insensitivity Syndrome , Hernia, Inguinal , Androgen-Insensitivity Syndrome/diagnosis , Androgen-Insensitivity Syndrome/genetics , Child , Female , Hernia, Inguinal/genetics , Hernia, Inguinal/surgery , Herniorrhaphy , Humans , Indonesia , Karyotyping , MaleABSTRACT
Ovarian deficiency, including premature ovarian insufficiency (POI) and diminished ovarian reserve (DOR), represents one of the main causes of female infertility. POI is a genetically heterogeneous condition but current understanding of its genetic basis is far from complete, with the cause remaining unknown in the majority of patients. The genes that regulate DOR have been reported but the genetic basis of DOR has not been explored in depth. Both conditions are likely to lie along a continuum of degrees of decrease in ovarian reserve. We performed genomic analysis via whole exome sequencing (WES) followed by in silico analyses and functional experiments to investigate the genetic cause of ovarian deficiency in ten affected women. We achieved diagnoses for three of them, including the identification of novel variants in STAG3, GDF9, and FANCM. We identified potentially causative FSHR variants in another patient. This is the second report of biallelic GDF9 and FANCM variants, and, combined with functional support, validates these genes as bone fide autosomal recessive "POI genes". We also identified new candidate genes, NRIP1, XPO1, and MACF1. These genes have been linked to ovarian function in mouse, pig, and zebrafish respectively, but never in humans. In the case of NRIP1, we provide functional support for the deleterious nature of the variant via SUMOylation and luciferase/ß-galactosidase reporter assays. Our study provides multiple insights into the genetic basis of POI/DOR. We have further elucidated the involvement of GDF9, FANCM, STAG3 and FSHR in POI pathogenesis, and propose new candidate genes, NRIP1, XPO1, and MACF1, which should be the focus of future studies.
Subject(s)
Karyopherins/genetics , Microfilament Proteins/genetics , Nuclear Receptor Interacting Protein 1/genetics , Ovarian Reserve/genetics , Primary Ovarian Insufficiency/genetics , Receptors, Cytoplasmic and Nuclear/genetics , Adolescent , Cell Cycle Proteins/genetics , DNA Helicases/genetics , Female , Genomics , Growth Differentiation Factor 9/genetics , Humans , Infertility, Female , Menopause, Premature/genetics , Ovarian Diseases , Exome Sequencing , Young Adult , Exportin 1 ProteinABSTRACT
Infertility, a global problem affecting up to 15% of couples, can have varied causes ranging from natural ageing to the pathological development or function of the reproductive organs. One form of female infertility is premature ovarian insufficiency (POI), affecting up to 1 in 100 women and characterised by amenorrhoea and elevated FSH before the age of 40. POI can have a genetic basis, with over 50 causative genes identified. Non-obstructive azoospermia (NOA), a form of male infertility characterised by the absence of sperm in semen, has an incidence of 1% and is similarly heterogeneous. The genetic basis of male and female infertility is poorly understood with the majority of cases having no known cause. Here, we study a case of familial infertility including a proband with POI and her brother with NOA. We performed whole-exome sequencing (WES) and identified a homozygous STAG3 missense variant that segregated with infertility. STAG3 encodes a component of the meiosis cohesin complex required for sister chromatid separation. We report the first pathogenic homozygous missense variant in STAG3 and the first STAG3 variant associated with both male and female infertility. We also demonstrate limitations of WES for the analysis of homologous DNA sequences, with this variant being ambiguous or missed by independent WES protocols and its homozygosity only being established via long-range nested PCR.
Subject(s)
Azoospermia/genetics , Cell Cycle Proteins/genetics , Mutation, Missense , Primary Ovarian Insufficiency/genetics , Adult , Consanguinity , Female , Homozygote , Humans , Infertility, Female/genetics , Infertility, Male/genetics , Male , Pedigree , SiblingsABSTRACT
Perrault syndrome is a rare heterogeneous condition characterised by sensorineural hearing loss and premature ovarian insufficiency. Additional neuromuscular pathology is observed in some patients. There are six genes in which variants are known to cause Perrault syndrome; however, these explain only a minority of cases. We investigated the genetic cause of Perrault syndrome in seven affected individuals from five different families, successfully identifying the cause in four patients. This included previously reported and novel causative variants in known Perrault syndrome genes, CLPP and LARS2, involved in mitochondrial proteolysis and mitochondrial translation, respectively. For the first time, we show that pathogenic variants in PEX6 can present clinically as Perrault syndrome. PEX6 encodes a peroxisomal biogenesis factor, and we demonstrate evidence of peroxisomal dysfunction in patient serum. This study consolidates the clinical overlap between Perrault syndrome and peroxisomal disorders, and highlights the need to consider ovarian function in individuals with atypical/mild peroxisomal disorders. The remaining patients had variants in candidate genes such as TFAM, involved in mtDNA transcription, replication, and packaging, and GGPS1 involved in mevalonate/coenzyme Q10 biosynthesis and whose enzymatic product is required for mouse folliculogenesis. This genomic study highlights the diverse molecular landscape of this poorly understood syndrome.