Miscarriage risk assessment: a bioinformatic approach to identifying candidate lethal genes and variants.

PURPOSE: Miscarriage, often resulting from a variety of genetic factors, is a common pregnancy outcome. Preconception genetic carrier screening (PGCS) identifies at-risk partners for newborn genetic disorders; however, PGCS panels currently lack miscarriage-related genes. In this study, we evaluated the potential impact of both known and candidate genes on prenatal lethality and the effectiveness of PGCS in diverse populations. METHODS: We analyzed 125,748 human exome sequences and mouse and human gene function databases. Our goals were to identify genes crucial for human fetal survival (lethal genes), to find variants not present in a homozygous state in healthy humans, and to estimate carrier rates of known and candidate lethal genes in various populations and ethnic groups. RESULTS: This study identified 138 genes in which heterozygous lethal variants are present in the general population with a frequency of 0.5% or greater. Screening for these 138 genes could identify 4.6% (in the Finnish population) to 39.8% (in the East Asian population) of couples at risk of miscarriage. This explains the cause of pregnancy loss in approximately 1.1-10% of cases affected by biallelic lethal variants. CONCLUSION: This study has identified a set of genes and variants potentially associated with lethality across different ethnic backgrounds. The variation of these genes across ethnic groups underscores the need for a comprehensive, pan-ethnic PGCS panel that includes genes related to miscarriage.

45,X/46,XY mosaicism: Clinical manifestations and long term follow-up.

45,X/46,XY chromosomal mosaicism presents a range of clinical manifestations, including phenotypes from Turner syndrome through genital abnormalities to apparently unaffected phenotypic males; however, the full clinical spectrum has not yet been fully delineated since prior studies on the clinical phenotype and associated risk of gonadal tumors included small cohorts and limited follow-up. To better describe the clinical manifestations and long-term outcome of patients with 45,X/46,XY mosaicism. We conducted a retrospective chart review of patients with 45,X/46,XY from three health centers (Hospital for Sick Children and Mount Sinai Hospital in Canada, and University of Pittsburgh Medical Center in United States). Of 100 patients with 45,X/46,XY karyotype, 47 were raised as females and 53 as males. Females were significantly shorter than males (p = 0.04) and height Z-score was significantly decreased with age for both genders (p = 0.02). Growth hormone (GH) treatment did not result in a significant height increase compared to the untreated group (p = 0.5). All females required puberty induction in contrast to majority of males. Five females were diagnosed with gonadal tumors, while no males were affected. Around 58% of patients exhibited at least one Turner syndrome stigmata. This study expands the clinical spectrum, long-term outcomes, and associated tumor risk in a large cohort of patients with 45,X/46,XY mosaicism. Additionally, it highlights our experience with GH therapy and prophylactic gonadectomy.

Prenatal and fetal diagnosis of trisomy 18 after low-risk cell-free fetal DNA screening: A report of four cases.

INTRODUCTION: Non-Invasive Prenatal Screening (NIPS) is a useful screening method for common aneuploidies that can occur in pregnancies. It yields high sensitivities and specificities for the targeted conditions it tests for. Most commonly, these include Trisomies in chromosomes 21, 18, and 13, as well as aneuploidies in chromosomes X and Y. It does not, however, replace diagnostic testing. We review four cases seen by our institutions of patients who had NIPS performed with low-risk results and subsequently had fetuses affected with trisomy 18. METHODS: All fetal samples were evaluated by level II anatomic ultrasound and tested on amniocytes or products of conception through karyotype or chromosomal microarray following low-risk NIPS. RESULTS: None of the fetuses showed evidence of mosaicism and had features (both on ultrasound and postnatally) consistent with Trisomy 18. Postnatal fluorescence in situ hybridization performed on Formalin-Fixed Paraffin-Embedded tissue from 3 of the affected pregnancies' placentas identified mosaicism of trisomy 18. DISCUSSION: We discuss the possible explanations for the discrepancy between NIPS results and fetal karyotype, including, but not limited to placental mosaicism, placental size, and limitations of NIPS as a screening test.

Testis formation in XX individuals resulting from novel pathogenic variants in Wilms' tumor 1 (WT1) gene.

Sex determination in mammals is governed by antagonistic interactions of two genetic pathways, imbalance in which may lead to disorders/differences of sex development (DSD) in human. Among 46,XX individuals with testicular DSD (TDSD) or ovotesticular DSD (OTDSD), testicular tissue is present in the gonad. Although the testis-determining gene SRY is present in many cases, the etiology is unknown in most SRY-negative patients. We performed exome sequencing on 78 individuals with 46,XX TDSD/OTDSD of unknown genetic etiology and identified seven (8.97%) with heterozygous variants affecting the fourth zinc finger (ZF4) of Wilms' tumor 1 (WT1) (p.Ser478Thrfs*17, p.Pro481Leufs*15, p.Lys491Glu, p.Arg495Gln [x3], p.Arg495Gly). The variants were de novo in six families (P = 4.4 × 10-6), and the incidence of WT1 variants in 46,XX DSD is enriched compared to control populations (P < 1.8 × 10-4). The introduction of ZF4 mutants into a human granulosa cell line resulted in up-regulation of endogenous Sertoli cell transcripts and Wt1Arg495Gly/Arg495Gly XX mice display masculinization of the fetal gonads. The phenotype could be explained by the ability of the mutated proteins to physically interact with and sequester a key pro-ovary factor ß-CATENIN, which may lead to up-regulation of testis-specific pathway. Our data show that unlike previous association of WT1 and 46,XY DSD, ZF4 variants of WT1 are a relatively common cause of 46,XX TDSD/OTDSD. This expands the spectrum of phenotypes associated with WT1 variants and shows that the WT1 protein affecting ZF4 can function as a protestis factor in an XX chromosomal context.

Heterozygous TP63 pathogenic variants in isolated primary ovarian insufficiency.

PURPOSE: Our study aimed to identify the genetic causes of non-syndromic primary ovarian insufficiency (POI) in female patients. METHODS: We performed whole exome sequencing in females suffering from isolated POI and in their available family members. Copy number variations were validated by long-range PCR and Sanger sequencing, and conservation analysis was used to evaluate the impact of sequence variants on protein composition. RESULTS: We detected two pathogenic TP63 heterozygous deleterious single nucleotide variants and a novel TP63 intragenic copy number alteration in three unrelated women with isolated POI. Two of these genetic variants are predicted to result in loss of transactivation inhibition of p63, whereas the third one affects the first exon of the ΔNp63 isoforms. CONCLUSION: Our results broaden the spectrum of TP63-related disorders, which now includes sporadic and familial, isolated, and syndromic POI. Genomic variants that impair the transactivation inhibitory domain of the TAp63α isoform are the cause of non-syndromic POI. Additionally, variants affecting only the ΔNp63 isoforms may result in isolated POI. In patients with isolated POI, careful evaluation of genomic variants in pleiotropic genes such as TP63 will be essential to establish a full clinical spectrum and atypical presentation of a disorder.

B-Cell Acute Lymphoblastic Leukemia with iAMP21 in a Patient with Constitutional Ring Chromosome 21.

Pediatric B-cell acute lymphoblastic leukemia (B-ALL) is associated with various specific cytogenetic and molecular markers that significantly influence treatment and prognosis. Intrachromosomal amplification of chromosome 21 (iAMP21) defines a rare distinct cytogenetic subgroup of childhood B-ALL, which is characterized by amplification of region 21q22.12 comprising the RUNX1 gene. Constitutional structural chromosomal abnormalities involving chromosome 21 confer an increased risk for B-ALL with iAMP21. Here, we report the development of B-ALL with iAMP21 in a 9-year-old child with a constitutional ring chromosome 21, r(21)c, uncovered after B-ALL diagnosis. Cytogenetic and microarray analysis of the post-therapy sample revealed an abnormal chromosome 21 lacking a satellite and having a deletion of the terminal 22q22.3 region, consistent with a constitutional ring chromosome 21, r(21)(p11.2q22). On a retrospective analysis, this ring chromosome was observed in the normal cells in the pre-treatment diagnostic specimen. Constitutional ring chromosome 21 may remain undetected in patients with mild or no neurodevelopmental phenotype, posing an unknown lifelong risk of developing B-ALL with iAMP21. Individuals with constitutional structural chromosome 21 rearrangements such as ring 21 require a close surveillance and long-term follow-up studies to establish their risk of B-ALL relapse and possibility of developing other malignancies. Germline analysis is recommended to all pediatric patients with iAMP21-related B-ALL to rule out structural chromosome 21 rearrangements and to elucidate molecular mechanisms of iAMP21 formation.

Histopathologic, immunophenotypic, and mutational landscape of follicular lymphomas with plasmacytic differentiation.

Follicular lymphomas with plasmacytic differentiation (FL-PCD) include two major subtypes: one with predominantly interfollicular PCD that usually harbors a BCL2 rearrangement (BCL2-R), and a second that has predominantly intrafollicular PCD and the frequent absence of a BCL2-R. It is proposed that these latter cases share some features with marginal zone lymphomas (MZL). To further explore this hypothesis in an expanded cohort of FL-PCD, a clinicopathologic investigation of 25 such cases was undertaken including an analysis of their mutational landscape. The 10 interfollicular FL-PCDs exhibited typical intrafollicular centrocytes/centroblasts (90%), CD10 expression (90%), full PCD including expression of CD138 by the plasma cells (PC) (100%), and PCs with class-switched immunoglobulin heavy chains (70%). These cases were BCL2-R positive (100%), BCL6-R positive in 30%, lacked extra BCL2 copies, and only 22% had extra copies of BCL6. Similar to classic FLs, 80% of interfollicular FL-PCDs harbored mutations in epigenetic regulators KMT2D (70%), CREBBP (40%), and/or EZH2 (30%). In contrast, only 45% of 11 intrafollicular FL-PCDs demonstrated typical intrafollicular centrocytes/centroblasts, 55% were CD10(-), 80% contained IgM+ PCs, and only 27% harbored BCL2-Rs. BCL6-Rs were identified in 27% of intrafollicular FL-PCD, while 60% showed extra copies of BCL2 and 50% extra copies of BCL6, consistent with complete or partial trisomies of chromosomes 18 and 3, respectively. Only 54% of intrafollicular FL-PCDs showed mutations in epigenetic regulators. Both subtypes showed mutational differences compared to classic FL, but only the interfollicular subtype showed differences from what is reported for nodal MZL. Four additional cases showed mixed intra- and interfollicular PCD. These results suggest that FL-PCD has some distinctive features and supports the existence of two major subtypes. The interfollicular PCD subtype shares many features with classic FL. The intrafollicular FL-PCDs are more heterogeneous, have differences from classic FL, and have a greater morphologic, immunophenotypic, and genetic overlap with MZL.

Therapy-related myeloid neoplasms with different latencies: a detailed clinicopathologic analysis.

Therapy-related myeloid neoplasm (t-MN) arising in patients with prior cytotoxic treatments is considered a distinct entity due to its unfavorable prognosis. Latencies between the initial cytotoxic therapy and the occurrence of t-MNs vary but usually fall between 1 and 10 years. t-MNs with unusually short or long latencies are not well characterized. It is unclear if they are biologically similar to the ones with ordinary latencies and should be kept in the t-MN entity. We compiled a cohort of t-MN cases including short (<1 year), ordinary (1-10 years), and extended (>10 years) latencies from two tertiary medical centers. Both the t-MNs with ordinary and extended latencies showed high likelihood of high-risk genetic abnormalities and demonstrated no significant survival differences. But the t-MNs with extended latencies were more likely associated with history of multiple cancers (p = 0.007) and were younger at the time of cytotoxic treatments (p < 0.001) when compared to the t-MNs with ordinary latencies. The t-MN with short latencies appears to be a very rare and highly heterogeneous group. In summary, the genetic composition appears similar in the t-MNs with ordinary and extended latencies. However, the association between the t-MN with extended latencies and history of multiple cancers raises a possibility that cancer predisposition may contribute to the accumulation of genetic abnormalities in these patients. Investigation into potential germline mutations in the t-MN patients with extended latencies may provide important information for related family members.

Carrier frequency of autosomal recessive genetic conditions in diverse populations: Lessons learned from the genome aggregation database.

An equitable approach by the American College of Medical Genetics and Genomics (ACMG) has recently recommended carrier screening for genes associated with moderate to severe autosomal recessive conditions with a carrier frequency of ≥1/200 in the Genome Aggregation Database exomes (gnomADv2.0.2). We analyzed carrier frequencies in gnomADv3.1.1 genomes representing diverse populations. ClinVar data on 35 996 pathogenic/likely pathogenic variants in 419 genes were used to estimate the gnomAD frequency of heterozygous carriers. We found that ninety-two genes had a carrier frequency of ≥1/200, of which 63 were shared between v3.1.1 and v2.0.2 and 29 were new in v3.1.1. Addition of new populations (Amish, Finnish and Middle Eastern) increased the number of new genes with a carrier frequency of ≥1/200 to 71. Changes in carrier frequencies were attributed to new gnomAD populations, different sample sizes, new ClinVar data, and technical differences between exomes and genomes. This study highlights the dynamic changes in carrier frequencies due to new datasets from diverse populations and provides updated carrier frequencies based on the combined data from 184 352 genomes and exomes in gnomAD. We recommend a periodic review for inclusion of new population data to update carrier screening panels in the future.

B-cell acute lymphoblastic leukemia with iAMP21 in a patient with Down syndrome due to a constitutional isodicentric chromosome 21.

Pediatric B-cell acute lymphoblastic leukemia (B-ALL) is associated with various specific cytogenetic and molecular markers that have significant influence on treatment and prognosis. A subset of children has a much higher risk of developing B-ALL due to constitutional genetic alterations such as trisomy 21 (Down's syndrome). In these patients, B-ALL is often associated with specific genomic profiles leading to leukemic transformation. In rare cases, constitutional structural chromosomal abnormalities involving chromosome 21, such as the der(15;21) Robertsonian translocation and a ring 21 chromosome, have been associated with intrachromosomal amplification of chromosome 21 (iAMP21) B-ALL. Here, we report the development of B-ALL in a child with Down's syndrome who carries a constitutional isodicentric chromosome 21 [idic(21)], described previously by Putra et al., 2017. This idic(21) appeared to be unstable during mitosis, leading to somatic rearrangements consistent with iAMP21 amplification, resulting in the development of leukemia. In this case, a single constitutional structural chromosome 21 rearrangement resulted in a B-ALL with Down syndrome-associated genomic lesions as well as genomic lesions not common to the Down syndrome subtype of B-ALL. Our findings highlight the need for counseling of individuals with constitutional structural chromosome 21 rearrangements regarding their risks of developing a B-ALL.

Reproductive outcomes in individuals with chromosomal reciprocal translocations.

PURPOSE: Patients with reciprocal balanced translocations (RBT) have a risk for recurrent pregnancy losses (RPL), affected child, and infertility. Currently, genetic counseling is based on karyotypes found among the products of conception (POC), although factors influencing the success of assisted reproductive technologies (ART) in RBT couples are not established. METHODS: Cytogenetic results from 261 POC and offspring of the parents (113 women and 90 men) with RBT were evaluated. Chromosome segregation modes and number of euploid embryos were assessed in couples undergoing in vitro fertilization. RESULTS: Patients with translocations involving an acrocentric chromosome have a higher risk of unbalanced gametes caused by a 3:1 segregation. Female RBT patients have a statistically higher risk of aneuploidy due to an interchromosomal effect. The rate of euploid embryos is low due to meiosis I malsegregation of RBT, meiosis II nondisjunction, additional whole chromosome or segmental aneusomies. RBT patients with RPL have a higher rate of miscarriage of euploid fetuses with RBT. CONCLUSION: Chromosome-specific factors, female gender, age, and history of RPL are the risk elements influencing pregnancy and in vitro fertilization success in RBT patients. Chromosomal microarray analysis of POC is necessary to provide an accurate and timely diagnosis for patients with adverse reproductive outcomes.

Cytogenetic signatures of recurrent pregnancy losses.

OBJECTIVES: To investigate the incidence of chromosomal abnormalities in the products of conception (POC) of patients with spontaneous miscarriages (SM) and with recurrent pregnancy losses (RPL) and to determine biological mechanisms contributing to RPL. METHODS: During a 20-year period, 12 096 POC samples underwent classical chromosome analysis. Cytogenetic findings were compared between the SM and RPL cohorts. RESULTS: Analysis of RPL cohort has identified an increased incidence of inherited and de novo structural chromosome abnormalities, recurrent polyploid conceptions, and complex mosaic alterations. These abnormalities are the signature of genomic instability, posing a high risk of genetic abnormalities to offspring independent of maternal age. Predominance of male conceptions in the RPL cohort points toward an X-linked etiology and gender-specific intolerance for certain genetic abnormalities. CONCLUSIONS: Our study showed several possible genetic etiologies of RPL, including parental structural chromosome rearrangements, predisposition to meiotic nondisjunction, and genomic instability. Loss of karyotypically normal fetuses might be attributed to defects in genes essential for fetal development, as well as aberrations affecting the X chromosome. Molecular studies of parental and POC genomes will help to identify inherited defects in genes involved in meiotic divisions and DNA repair to confirm our hypotheses, and to discover novel fetal-essential genes.

Mutations involving the SRY-related gene SOX8 are associated with a spectrum of human reproductive anomalies.

SOX8 is an HMG-box transcription factor closely related to SRY and SOX9. Deletion of the gene encoding Sox8 in mice causes reproductive dysfunction but the role of SOX8 in humans is unknown. Here, we show that SOX8 is expressed in the somatic cells of the early developing gonad in the human and influences human sex determination. We identified two individuals with 46, XY disorders/differences in sex development (DSD) and chromosomal rearrangements encompassing the SOX8 locus and a third individual with 46, XY DSD and a missense mutation in the HMG-box of SOX8. In vitro functional assays indicate that this mutation alters the biological activity of the protein. As an emerging body of evidence suggests that DSDs and infertility can have common etiologies, we also analysed SOX8 in a cohort of infertile men (n = 274) and two independent cohorts of women with primary ovarian insufficiency (POI; n = 153 and n = 104). SOX8 mutations were found at increased frequency in oligozoospermic men (3.5%; P < 0.05) and POI (5.06%; P = 4.5 × 10-5) as compared with fertile/normospermic control populations (0.74%). The mutant proteins identified altered SOX8 biological activity as compared with the wild-type protein. These data demonstrate that SOX8 plays an important role in human reproduction and SOX8 mutations contribute to a spectrum of phenotypes including 46, XY DSD, male infertility and 46, XX POI.

Acute myeloid leukemia with isolated del(5q) is associated with IDH1/IDH2 mutations and better prognosis when compared to acute myeloid leukemia with complex karyotype including del(5q).

Myelodysplastic syndrome with isolated del(5q) is a well-recognized entity with a relatively favorable prognosis. Isolated del(5q) in acute myeloid leukemia is rare and acute myeloid leukemia cases with isolated del(5q) are not well characterized. Del(5q) has been shown to be a poor prognostic marker in acute myeloid leukemia based on multivariable analysis in large cohort studies, which contained mostly cases with del(5q) in the context of multiple chromosomal abnormalities. To further characterize acute myeloid leukemia with isolated del(5q), clinicopathologic characterization including mutation analysis was performed. During a 10-year period, we identified 12 cases of acute myeloid leukemia with isolated del(5q), 7 cases of acute myeloid leukemia with del(5q) plus one additional chromosome abnormality not involving chromosome 7, as well as two control groups composed of 124 cases of acute myeloid leukemia with complex karyotype including del(5q), and 40 cases of myelodysplastic syndrome with isolated del(5q). At diagnosis, cases of acute myeloid leukemia with isolated del(5q) had higher platelet counts (p = 0.044), hemoglobin (p = 0.011), and mean corpuscular volume (p = 0.017) compared with cases of acute myeloid leukemia with complex karyotype including del(5q). Acute myeloid leukemia with isolated del(5q) was less likely therapy-related (p = 0.037), more likely to have IDH1/IDH2 mutations (p = 0.009), and less likely to have TP53 mutations (p = 0.005) when compared to acute myeloid leukemia with complex karyotype including del(5q). Acute myeloid leukemia with isolated del(5q) also showed longer overall survival than acute myeloid leukemia with complex karyotype cases including del(5q) (p = 0.004). In summary, acute myeloid leukemia with isolated del(5q) appeared to show some distinct clinicopathologic and genomic features as compared to cases of acute myeloid leukemia with complex karyotype including del(5q).

Copy number alterations involving 59 ACMG-recommended secondary findings genes.

In clinical exome/genome sequencing, the American College of Medical Genetics and Genomics (ACMG) recommends reporting of secondary findings unrelated to a patient's phenotype when pathogenic single-nucleotide variants (SNVs) are observed in one of 59 genes associated with a life-threatening, medically actionable condition. Little is known about the incidence and sensitivity of chromosomal microarray analysis (CMA) for detection of pathogenic copy number variants (CNVs) comprising medically-actionable genes. Clinical CMA has been performed on 8865 individuals referred for molecular cytogenetic testing. We retrospectively reviewed the CMA results to identify patients with CNVs comprising genes included in the 59-ACMG list of secondary findings. We evaluated the clinical significance of these CNVs in respect to pathogenicity, phenotypic manifestations, and heritability. We identified 23 patients (0.26%) with relevant CNV either deletions comprising the entire gene or intragenic alterations involving one or more secondary findings genes. A number of patients and/or their family members with pathogenic CNVs manifest or expected to develop an anticipated clinical phenotype and would benefit from preventive management similar to the patients with pathogenic SNVs. To improve patients' care standardization should apply to reporting of both sequencing and CNVs obtained via clinical genome-wide analysis, including chromosomal microarray and exome/genome sequencing.

Four children with postnatally diagnosed mosaic trisomy 12: Clinical features, literature review, and current diagnostic capabilities of genetic testing.

Children or adults with mosaic trisomy 12 diagnosed postnatally are extremely rare. Only a small number of patients with this mosaicism have been reported in the literature. The clinical manifestation of mosaic trisomy 12 is variable, ranging from mild developmental delay to severe congenital anomaly and neonatal death. The trisomy 12 cells are not usually able to be detected by phytohemagglutinin stimulated peripheral blood chromosome analysis. The variability of phenotypes and the limited number of patients with this anomaly pose a challenge to predict the clinical outcomes. In this study, we present the phenotypes and laboratory findings in four patients and review the 11 previously reported patients with mosaic trisomy 12 diagnosed postnatally, as well as 11 patients with mosaic trisomy 12 diagnosed prenatally. The findings of this study provide useful information for laboratory diagnosis and clinical management of these patients.

Familial Infertility (Azoospermia and Cryptozoospermia) in Two Brothers-Carriers of t(1;7) Complex Chromosomal Rearrangement (CCR): Molecular Cytogenetic Analysis.

Structural aberrations involving more than two breakpoints on two or more chromosomes are known as complex chromosomal rearrangements (CCRs). They can reduce fertility through gametogenesis arrest developed due to disrupted chromosomal pairing in the pachytene stage. We present a familial case of two infertile brothers (with azoospermia and cryptozoospermia) and their mother, carriers of an exceptional type of CCR involving chromosomes 1 and 7 and three breakpoints. The aim was to identify whether meiotic disruption was caused by CCR and/or genomic mutations. Additionally, we performed a literature survey for male CCR carriers with reproductive failures. The characterization of the CCR chromosomes and potential genomic aberrations was performed using: G-banding using trypsin and Giemsa staining (GTG banding), fluorescent in situ hybridization (FISH) (including multicolor FISH (mFISH) and bacterial artificial chromosome (BAC)-FISH), and genome-wide array comparative genomic hybridization (aCGH). The CCR description was established as: der(1)(1qter->1q42.3::1p21->1q42.3::7p14.3->7pter), der(7)(1pter->1p2 1::7p14.3->7qter). aCGH revealed three rare genes variants: ASMT, GARNL3, and SESTD1, which were ruled out due to unlikely biological functions. The aCGH analysis of three breakpoint CCR regions did not reveal copy number variations (CNVs) with biologically plausible genes. Synaptonemal complex evaluation (brother-1; spermatocytes II/oligobiopsy; the silver staining technique) showed incomplete conjugation of the chromosomes. Associations between CCR and the sex chromosomes (by FISH) were not found. A meiotic segregation pattern (brother-2; ejaculated spermatozoa; FISH) revealed 29.21% genetically normal/balanced spermatozoa. The aCGH analysis could not detect smaller intergenic CNVs of few kb or smaller (indels of single exons or few nucleotides). Since chromosomal aberrations frequently do not affect the phenotype of the carrier, in contrast to the negative influence on spermatogenesis, there is an obvious need for genomic sequencing to investigate the point mutations that may be responsible for the differences between the azoospermic and cryptozoospermic phenotypes observed in a family. Progeny from the same parents provide a unique opportunity to discover a novel genomic background of male infertility.

Genetics of human female infertility†.

About 10% of women of reproductive age are unable to conceive or carry a pregnancy to term. Female factors alone account for at least 35% of all infertility cases and comprise a wide range of causes affecting ovarian development, maturation of oocytes, and fertilization competence, as well as the potential of a fertilized egg for preimplantation development, implantation, and fetal growth. Genetic abnormalities leading to infertility in females comprise large chromosome abnormalities, submicroscopic chromosome deletion and duplications, and DNA sequence variations in the genes that control numerous biological processes implicated in oogenesis, maintenance of ovarian reserve, hormonal signaling, and anatomical and functional development of female reproductive organs. Despite the great number of genes implicated in reproductive physiology by the study of animal models, only a subset of these genes is associated with human infertility. In this review, we mainly focus on genetic alterations identified in humans and summarize recent knowledge on the molecular pathways of oocyte development and maturation, the crucial role of maternal-effect factors during embryogenesis, and genetic conditions associated with ovarian dysgenesis, primary ovarian insufficiency, early embryonic lethality, and infertility.

A high-resolution X chromosome copy-number variation map in fertile females and women with primary ovarian insufficiency.

PURPOSE: Sex-biased expression of genes on the X chromosome is accomplished by a complex mechanism of dosage regulation that leads to anatomical and physiological differences between males and females. Copy-number variations (CNVs) may impact the human genome by either affecting gene dosage or disturbing a chromosome structural and/or functional integrity. METHODS: We performed a high-resolution CNV profiling to investigate the X chromosome integrity in cohorts of 269 fertile females and 111 women affected with primary ovarian insufficiency (POI) and assessed CNVs impact into functional and nonfunctional genomic elements. RESULTS: In POI patients, we observed a 2.5-fold enrichment for rare CNVs comprising ovary-expressed genes, and genes implicated in autoimmune response and apoptotic signaling. Moreover, there was a higher prevalence of deletions encompassing genes that escape X inactivation, noncoding RNAs, and intergenic DNA sequences among POI females, highlighting structural differences between X chromosomes of fertile and POI females. Furthermore, we discovered a ~4% carrier incidence for X-linked disorders among fertile women. CONCLUSION: We constructed a high-resolution map of female-specific CNVs that provides critical insights into the spectrum of human genetic variation, sex-specific disease risk factors, and reproductive potential. We discovered novel CNVs associated with ovarian dysfunction and support polygenic models for POI.

Early Bilateral Gonadoblastoma Associated With 45,X/46,XY Mosaicism: The Spectrum of Undifferentiated Gonadal Tissue and Gonadoblastoma in the First Months of Life.

45,X/46,XY mosaicism is one of a heterogenous group of congenital conditions known as differences (disorders) of sex development (DSD) that results in abnormal development of internal and external genitalia. Patients with DSD, particularly those with segments of the Y chromosome, are at increased risk for germ cell tumors including gonadoblastoma. Gonadoblastoma is a neoplasm comprised of a mixture of germ cells and elements resembling immature granulosa or Sertoli cells with or without Leydig cells or lutein-type cells in an ovarian type stroma. Gonadoblastoma has an increased prevalence of 15% to 40% in patients with 45,X/46,XY mosaicism and has been previously reported in patients as young as 5 months of age with that karyotype. Herein, we describe a 3-month-old child with 45,X/46,XY karyotype who was referred for the evaluation of asymmetric labia majora. Additional evaluation revealed left streak gonad and right dysplastic/dysgenetic testis. Both gonads contained foci of cells typical for gonadoblastoma as well as undifferentiated gonadal tissue, underscoring the potential for very early infantile gonadoblastoma and the spectrum of developmental anomalies associated with this karyotype.