Chromosomal abnormalities associated with fetal pleural effusion (I): General overview.

Fetal pleural effusion has been reported to be associated with chromosomal abnormalities, genetic syndromes, obstructive uropathy, lymphatic vessel abnormalities such as Noonan syndrome, RASopathy and congenital lymphatic anomalies, thoracic cavity defects, Rh or ABO incompatibility, non-immune hydrops fetalis, infections, congenital cardiac anomalies, metabolic diseases and hematologic diseases such as α-thalassemia. This review provides an overview of chromosomal abnormalities associated with fetal pleural effusion which is useful for genetic counseling and fetal therapy at prenatal diagnosis of fetal pleural effusion.

Syndromic and single gene disorders associated with fetal pleural effusion (I): Noonan syndrome, RASopathy and congenital lymphatic anomalies.

Fetal pleural effusion has been reported to be associated with chromosomal abnormalities, genetic syndromes, obstructive uropathy, lymphatic vessel abnormalities such as Noonan syndrome, RASopathy and congenital lymphatic anomalies, thoracic cavity defects, Rh or ABO incompatibility, non-immune hydrops fetalis, infections, congenital cardiac anomalies, metabolic diseases and hematologic diseases such as α-thalassemia. This review provides an overview of syndromic and single gene disorders associated with fetal pleural effusion that is useful for genetic counseling and fetal therapy at prenatal diagnosis of fetal pleural effusion.

Chromosomal abnormalities associated with fetal pleural effusion (II): Specific and non-specific chromosome aberrations.

Fetal pleural effusion has been reported to be associated with chromosomal abnormalities, genetic syndromes, obstructive uropathy, lymphatic vessel abnormalities such as Noonan syndrome, RASopathy and congenital lymphatic anomalies, thoracic cavity defects, Rh or ABO incompatibility, non-immune hydrops fetalis, infections, congenital cardiac anomalies, metabolic diseases and hematologic diseases such as α-thalassemia. This review provides a comprehensive view of specific and non-specific chromosome aberrations associated with fetal pleural effusion which is useful for genetic counseling and fetal therapy at prenatal diagnosis of fetal pleural effusion.

Retrospective study and implementation of a low-cost LAMP-turbidimetric assay for screening α0-thalassemia (SEA deletion): preventing and controlling Hb Bart's hydrops fetalis syndrome in Thailand.

Homozygous α0-thalassemia (SEA deletion) or Hb Bart's hydrops fetalis syndrome is a significant public health issue in Thailand and Southeast Asia. A prevention and control program has been implemented in this region. This study focuses on retrospective laboratory data collected between January 2021 and April 2023 at a single center. Additionally, we developed a low-cost LAMP-turbidimetric assay to propose in the screening strategy. A total of 3,623 samples underwent screening tests (MCV, MCH, and DCIP), including 1,658 couple screenings (84.25%) and 310 single pregnant screenings (15.75%). Negative screenings, which did not require further investigation, were found in 75.51% for couple screenings and 46.58% for single pregnant screenings. At hemoglobin (Hb) analysis identified 129 couples which had fetuses at risk of severe thalassemia, whereas molecular analysis during the retrospective period revealed 210 samples with different genotypes. These remaining samples were validated using the low-cost LAMP-turbidimetric assay to detect α0-thalassemia (SEA deletion). The developed LAMP turbidimetric assay demonstrated a sensitivity and specificity of 100% (36/36 × 100) and 97.7% (170/174 × 100), respectively, when compared with gap-PCR. Furthermore, we propose a strategy involving the addition of the low-cost LAMP-turbidimetric assay before performing the gold standard. This strategy represents a cost-saving of USD 2,608 based on 210 samples that required DNA analysis. Finally, the developed LAMP turbidimetric assays offer advantages such as reduced time, workload, cost savings, no need for highly developed instruments, and a straightforward interpreting process. Therefore, implementation of LAMP assays into routine settings would be improve the efficiency of prevention and control program for severe thalassemia disease in this region.

Neonates with a prenatal diagnosis of hydrops fetalis: A 10-year experience in a tertiary care center.

INTRODUCTION: Hydrops fetalis (HF) is a rare condition with a high mortality. This study analysed the obstetric and perinatal outcomes of antenatally diagnosed HF according to its aetiology and the possibility of intrauterine treatment (IUT). PATIENTS AND METHODS: We carried out a retrospective review of the health records of 164 pregnant women with a prenatal diagnosis of HF in a tertiary care centre between 2011-2021. We analysed prenatal interventions, clinical findings, aetiologies and obstetric and live-born infant outcomes. RESULTS: An invasive prenatal study had been performed in 79.3% cases. The most common aetiologies were genetic disorders (31%), TORCH and parvovirus B19 infections (9.7%) and structural heart diseases (9.1%). Intrauterine treatment was performed in 25.6%, and 74.4% of pregnancies were terminated. Pregnancies with a prenatal diagnosis of genetic or chromosomal disorders had higher rates of elective termination compared to other aetiologies (P < .01). Among all pregnancies, only 25.6% resulted in live births (LBs), most of them preterm. Perinatal and 1-year survival rates were higher in the group that received IUT (P < .001). Among the LBs, structural heart diseases had the worst survival rates, while the aetiology with the best outcomes was tachyarrhythmia. Survival at 1 year of life among those born alive was 70%, but 58.6% of these infants had significant morbidity at discharge. CONCLUSIONS: Despite advances in the management of FH, the poor obstetric prognosis, perinatal mortality and morbidity of survivors is still significant. These data are important for the purpose of counselling families when HF is diagnosed antenatally.

Homozygous SPTA1-associated hereditary pyropoikilocytosis presenting as hydrops fetalis.

INTRODUCTION: Hereditary pyropoikilocytosis (HPP) is a heterogeneous inherited disorder of red blood cell (RBC) membrane and cytoskeletal proteins that leads to hemolytic anemia. HPP is characterized by marked poikilocytosis, microspherocytes, RBC fragmentation, and elliptocytes on peripheral blood smear. Mutations in SPTA1 can cause HPP due to a quantitative defect in α-spectrin and can lead to profound fetal anemia and nonimmune hydrops fetalis, which can be managed with intrauterine transfusion. CASE PRESENTATION: We present a case of a 26-year-old G4P2102 woman of Amish-Mennonite ancestry with a pregnancy complicated by fetal homozygosity for an SPTA1 gene variant (SPTA1c.6154delG) as well as severe fetal anemia and hydrops fetalis, which was managed with four intrauterine transfusions between 26 and 30 weeks gestation. Pre-transfusion peripheral smears from fetal blood samples showed RBC morphology consistent with HPP. The neonate had severe hyperbilirubinemia at birth, which has resolved, but remains transfusion-dependent at 6 months of life. DISCUSSION/CONCLUSION: To our knowledge, this is the first report that correlates homozygosity of the SPTA1c.6154delG gene variant with RBC dysmorphology and establishes the diagnosis of HPP.

RASopathies are the most common set of monogenic syndromes identified by exome sequencing for nonimmune hydrops fetalis: A systematic review and meta-analysis.

RASopathies are a group of malformation syndromes known to lead to nonimmune hydrops fetalis (NIHF) in severe presentations. Pathogenic variants can be de novo or parentally inherited. Despite being a known frequent presentation, the fraction of monogenic NIHF cases due to RASopathies is limited in the literature. Also, the specific parental contribution of RASopathies to NIHF is not well described. Our objective was to review pooled exome sequencing (ES) diagnostic yield of RASopathies for NIHF and to determine the parental contribution of RASopathy to NIHF. We performed a systematic review of prenatal ES studies from January 1, 2000 to August 1, 2022. Thirty-six studies met inclusion criteria. Cases with RASopathy gene variants were reviewed. NIHF cases were further classified as isolated or non-isolated. Thirty-six ES studies including 46 pregnancies with NIHF and a diagnosed RASopathy were reviewed. Forty-four diagnostic variants and 2 variants of uncertain significance in 12 RASopathy genes were identified. Expanding on what was previously published, a total of 506 NIHF cases were extracted with 191 cases yielding a positive diagnosis by ES. The overall rate of RASopathy diagnosis in clinically diagnosed NIHF cases was 9% (44/506). The rate of RASopathy diagnosis among NIHF cases with positive genetic diagnosis by ES was 23% (44/191). Of the 46 cases identified, 13 (28%) variants were parentally inherited; specifically, 5/13 (38%) maternal, 3/13 (23%) paternal, 2/13 (15%) biparental, and 3/13 (23%) unspecified. Majority of NIHF cases 29/46 (63%) were isolated. Among NIHF cases with positive ES diagnoses, RASopathy diagnostic yield by ES was 23%. NIHF secondary to RASopathies was parentally inherited in 28% of cases. Most cases of NIHF due to RASopathy were isolated, with no prenatal detection of associated anomalies.

Refractory supraventricular fetal tachycardia as a cause of non-immune hydrops: management conundrum.

Supraventricular tachyarrhythmia (SVT) is the most common form of fetal tachyarrhythmias. The presentation can vary from ill-defined, non-sustained episodes of tachyarrhythmia to frank non-immune hydrops. The standard of care is transplacental therapy by treating the mother with oral antiarrhythmic drugs, followed by direct fetal therapy in refractory cases. We report a case of primigravida in her late 20s, who presented at 28.1 weeks of gestation with fetal hydrops and SVT. She was initially managed with oral digoxin and flecainide, but due to worsening hydrops, risk of fetal demise and extreme prematurity, further management by direct fetal therapy was given in terms of intramuscular digoxin and intraperitoneal flecainide. Following which, the fetus had a favourable outcome. This case highlights the possible role of direct fetal therapy in refractory cases of SVT.

Prenatal diagnosis of mucopolysaccharidosis type VII facilitating treatment in neonatal period.

Duo exome testing was performed on a fetus conceived via in vitro fertilization with an egg donor. The fetus presented with non-immune hydrops fetalis (NIHF) at 20 + 0 weeks gestation. Two variants were detected in the GUSB gene. Biallelic pathogenic variants cause mucopolysaccharidosis type VII (MPS-VII), which can present with NIHF prenatally. At the time of analysis and initial report, one variant was classified as likely pathogenic and the other as of uncertain clinical significance. Biochemical testing of the amniotic fluid supernatant showed elevated glycosaminoglycans and low ß-glucuronidase activity consistent with the diagnosis of MPS-VII. This evidence allowed the upgrade of the pathogenicity for both variants, confirming the diagnosis of MPS-VII. The infant was born at 36 + 5 weeks and enzyme replacement therapy (ERT) using vestronidase was initiated at 20 days with planning for hematopoietic stem cell transplant ongoing. The ERT therapy has been well tolerated, with decreasing quantitative urine glycosaminoglycans. Long-term follow up is required to determine whether treatment has been successful. This case demonstrates the utility of alternative testing methods to clarify the pathogenicity of variants and the clinical utility of obtaining a diagnosis antenatally in facilitating treatment in the neonatal period, and specifically highlights MPS-VII as a treatable cause of NIHF.

Single-tube multiplex real-time PCR with EvaGreen and high-resolution melting analysis for diagnosis of α0-thalassemia--SEA,--THAI, and--CR type deletions.

Regions with a high prevalence of α-thalassemia (α-thal) require simple, rapid, and accurate tests for carrier screening and prenatal diagnosis. Diagnosis of multiple deletions in a single tube is necessary to clearly identify individuals with α0-thalassemia in the routine setting, especially in at-risk couples. Therefore, we aimed to develop a single-tube multiplex real-time PCR with EvaGreen and high-resolution melting (HRM) analysis for the identification of α0-thalassemia Southeast Asian (SEA), Thai and Chiang Rai (CR) type deletions. The results of the HRM analysis indicated that the amplified fragments from α0-thal--CR,--THAI,--SEA, and the wild-type α-globin gene had specific peak heights at mean melting temperature (Tm) values of 85.40°C, 86.50°C, 87.65°C, and 91.04°C, respectively. The frequencies of α0-thal--SEA,--THAI,--CR obtained from routine testing in 2,135 samples were 17.89%, 0.19% and 0.19%, respectively. This method would be useful for preventing Hb Bart's hydrops fetalis. Detection of multiple deletions in a single run is cost-effective, highly accurate and timesaving. This technique could enable wider α-thalassemia diagnosis in high prevalence areas and served as an example for thalassemia routine setting.

PIEZO1 is the most common monogenic etiology of non-immune hydrops fetalis detected by prenatal exome sequencing.

OBJECTIVE: To clarify the relevance of PIEZO1 variants detected by prenatal exome in the context of non-immune hydrops fetalis (NIHF). METHODS: A systematic review of prenatal exome studies from 1/1/2000-8/1/2022 was performed. Thirty-six studies met the inclusion criteria. PIEZO1 variants were categorized by disease mode (dominant (AD) versus recessive (AR)) and classified by the American College of Medical Genetics and Genomics (ACMG) guidelines. RESULTS: Twenty-two pregnancies with 35 distinct PIEZO1 variants were included. We deemed PIEZO1 variants to be "likely diagnostic" in 12/22 pregnancies, "possibly diagnostic" in 7/22, and "unlikely diagnostic" in 3/22. In total, 19 of 191 NIHF cases diagnosed by prenatal exome were attributed to PIEZO1. Among likely diagnosed cases, the disease mode was AR in eight and AD in four. PIEZO1 variants causing AR NIHF were characterized by loss of function and isolated NIHF phenotype. PIEZO1 variants causing AD NIHF were characterized by gain of function in red blood cells, scarcity in databases, and sporadic inheritance. Missense variants associated with NIHF were clustered in three domains: transmembrane helical unit 4 (THU4), THU5, and the Cap. CONCLUSION: PIEZO1 variants were reported in 10% of NIHF cases diagnosed by prenatal exome, making PIEZO1 the most common single gene reported in NIHF.

Prenatally Diagnosed Large Lung Lesions: Timing of Resection and Perinatal Outcomes.

INTRODUCTION: Fetuses with large lung lesions including congenital cystic adenomatoid malformations (CCAMs) are at risk for cardiopulmonary compromise. Prenatal maternal betamethasone and cyst drainage for micro- and macrocystic lesions respectively have improved outcomes yet some lesions remain large and require resection before birth (open fetal surgery, OFS), at delivery via an Ex Utero Intrapartum Treatment (EXIT), or immediately post cesarean section (section-to-resection, STR). We sought to compare prenatal characteristics and outcomes in fetuses undergoing OFS, EXIT, or STR to inform decision-making and prenatal counseling. METHODS: A single institution retrospective review was conducted evaluating patients undergoing OFS, EXIT, or STR for prenatally diagnosed lung lesions from 2000 to 2021. Specimens were reviewed by an anatomic pathologist. Lesions were divided into "CCAMs" (the largest pathology group) and "all lung lesions" since pathologic diagnosis is not possible during prenatal evaluation when care decisions are made. Prenatal variables included initial, greatest, and final CCAM volume-ratio (CVR), betamethasone use/frequency, cyst drainage, and the presence of hydrops. Outcomes included survival, ECMO utilization, NICU length of stay (LOS), postnatal nitric oxide use, and ventilator days. RESULTS: Sixty-nine percent (59 of 85 patients) of lung lesions undergoing resection were CCAMs. Among patients with pathologic diagnosis of CCAM, the initial, largest, and final CVRs were greatest in OFS followed by EXIT and STR patients. Similarly, the incidence of hydrops was significantly greater and the rate of hydrops resolution was lower in the OFS group. Although the rate of cyst drainage did not differ between groups, maternal betamethasone use varied significantly (OFS 60.0%, EXIT 100.0%, STR 74.3%; p = 0.0378). Notably, all OFS took place prior to 2014. There was no difference in survival, ventilator days, nitric oxide, NICU LOS, or ECMO between groups. In multiple variable logistic modeling, determinants of survival to NICU discharge among patients undergoing resection with a pathologic diagnosis of CCAM included initial CVR <3.5 and need for <3 maternal betamethasone doses. CONCLUSION: For CCAMs that remain large despite maternal betamethasone or cyst drainage, surgical resection via OFS, EXIT, or STR are viable options with favorable and comparable survival between groups. In the modern era there has been a shift from OFS and EXIT procedures to STR for fetuses with persistently large lung lesions. This shift has been fueled by the increased use of maternal betamethasone and introduction of a Special Delivery Unit during the study period and the appreciation of similar fetal and neonatal outcomes for STR vs. EXIT and OFS with reduced maternal morbidity associated with a STR. Accordingly, efforts to optimize multidisciplinary perinatal care for fetuses with large lung lesions are important to inform patient selection criteria and promote STR as the preferred surgical approach in the modern era. LEVEL OF EVIDENCE: Level IV.

Mirror syndrome: a systematic literature review.

OBJECTIVE: This study aimed to review the diagnostic criteria for mirror syndrome and describe its clinical presentation. DATA SOURCES: Databases from PubMed, Scopus, Cochrane Library, ClinicalTrials.gov, and CINAHL were inquired for case series containing ≥2 cases of mirror syndrome from inception to February 2022. STUDY ELIGIBILITY CRITERIA: Studies were included if they reported ≥2 cases of mirror syndrome and included case reports, case series, cohort studies, and case-control studies. STUDY APPRAISAL AND SYNTHESIS METHODS: The studies' quality and risk of bias were independently assessed. Data were tabulated using Microsoft Excel and summarized using narrative review and descriptive statistics. This systematic review was conducted according to the Preferred Reporting Item for Systematic Reviews and Meta-Analyses statement. All eligible references were assessed. Screening of records and data extraction were independently performed, and a third author resolved disagreements. RESULTS: Of 13 citations, 12 studies (n=82) reported diagnostic criteria for mirror syndrome: maternal edema (11/12), fetal hydrops (9/12), placental edema (6/12), placentomegaly (5/12), and preeclampsia (2/12); 12 studies (n=82) described the clinical presentation of mirror syndrome as maternal edema (62.2%), hypoalbuminemia (54.9%), anemia (39.0%), and new-onset hypertension (39.0%); 4 studies (n=36) reported that hemodilution was present in all patients; 8 studies (n=36) reported the etiology of fetal hydrops, with the most common being structural cardiac malformations (19.4%), alpha thalassemia (19.4%), Rh isoimmunization (13.9%), and nonimmune hydrops fetalis (13.9%); and 6 studies (n=47) reported maternal complications, 89.4% of which were major: postpartum hemorrhage (44.7%), hemorrhage requiring blood transfusion (19.1%), intensive care unit admission (12.8%), heart failure (10.6%), pulmonary edema (8.5%), and renal dysfunction (8.5%). In 39 cases, the reported fetal outcomes were stillbirth (66.6%) and neonatal or infant death (25.6%). The overall survival rate among continued pregnancies was 7.7%. CONCLUSION: The diagnostic criteria of mirror syndrome differed considerably among studies. Mirror syndrome clinical presentation overlapped with preeclampsia. Only 4 studies discussed hemodilution. Significant maternal morbidity and fetal mortality were associated with mirror syndrome. Further research is warranted to elucidate the pathogenesis of mirror syndrome to better guide clinicians in identifying and managing the condition.

Epidemiology of clinically significant forms of alpha- and beta-thalassemia: A global map of evidence and gaps.

This systematic literature review assessed the global prevalence and birth prevalence of clinically significant forms of alpha- and beta-thalassemia. Embase, MEDLINE, and the Cochrane Library were searched for observational studies published January 1, 2000, to September 21, 2021. Of 2093 unique records identified, 69 studies reported across 70 publications met eligibility criteria, including 6 records identified from bibliography searches. Thalassemia prevalence estimates varied across countries and even within countries. Across 23 population-based studies reporting clinically significant alpha-thalassemia (e.g., hemoglobin H disease and hemoglobin Bart's hydrops fetalis) and/or beta-thalassemia (beta-thalassemia intermedia, major, and/or hemoglobin E/beta-thalassemia), prevalence estimates per 100 000 people ranged from 0.2 in Spain (over 2014-2017) to 27.2 in Greece (2010-2015) for combined beta- plus alpha-thalassemia; from 0.03 in Spain (2014-2017) to 4.5 in Malaysia (2007-2018) for alpha-thalassemia; and from 0.2 in Spain (2014-2017) to 35.7 to 49.6 in Iraq (2003-2018) for beta-thalassemia. Overall, the estimated prevalence of thalassemia followed the predicted pattern of being higher in the Middle East, Asia, and Mediterranean than in Europe or North America. However, population-based prevalence estimates were not found for many countries, and there was heterogeneity in case definitions, diagnostic methodology, type of thalassemia reported, and details on transfusion requirements. Limited population-based birth prevalence data were found. Twenty-seven studies reported thalassemia prevalence from non-population-based samples. Results from such studies likely do not have countrywide generalizability as they tended to be from highly specific groups. To fully understand the global prevalence of thalassemia, up-to-date, population-based epidemiological data are needed for many countries.

Diagnosis of α-thalassaemia by colorimetric gap loop mediated isothermal amplification.

α-Thalassaemia is an inherited haemoglobin disorder that results from the defective synthesis of α-globin protein. Couples whom both carry the α-thalassaemia 1 gene are at risk of having a foetus with the most severe thalassaemia, Hb Bart's hydrops fetalis, with a risk of maternal mortality. However, haematological parameters alone cannot distinguish between a α-thalassaemia 1 carrier and a homozygous α-thalassaemia 2, in which one α-globin gene has been deleted on each chromosome. A rapid and accurate molecular detection assay is essential for prevention of the disease in populations where α-thalassaemia 1 is common. Multiplex Gap-PCR analysis is widely used for diagnosis of α-thalassaemia. However, the technique requires a thermocycler and post-amplification processing, which limits its application in primary care or in rural areas in developing countries. Loop mediated isothermal amplification (LAMP) amplifies target DNA at a constant temperature and does not require a thermocycler. This study developed a colorimetric Gap-LAMP using malachite green to allow naked eye visualization of two deletional α-thalassaemia 1 commonly found in Asian populations, the Southeast Asian type (--SEA) and the Thai type (--THAI) deletions. The Gap-LAMP was performed on DNA samples from 410 individuals carrying various α-thalassaemia gene defects with 100% concordance with conventional Gap-PCR analysis. This method eliminates post-amplification processing or the use of expensive sophisticated equipment and allows screening large populations for the prevention and control of α-thalassaemia.

Likely pathogenic variant in the BICD2 gene in fetus presenting with non-immune hydrops.

Trio exome sequencing was performed on a fetus presenting with severe hydrops fetalis at 21 + 0 weeks gestation. A novel de novo BICD2 missense variant was identified in the fetus. Pathogenic variants in the BICD2 gene are associated with lower extremity-predominant spinal muscular atrophy. The variant was initially classified as a variant of uncertain clinical significance (VUS) as at the time of analysis and initial report, pathogenic variants in the BICD2 gene specifically had not been associated with fetal hydrops and no other abnormalities had been detected. It was agreed in multidisciplinary team discussions to include the variant in the report as a VUS recommending phenotypic follow-up. The pregnancy was terminated and post-mortem findings were in keeping with a BICD2-pathogenic variant. In addition, a paper was published reporting another case with a pathogenic BICD2 variant presenting with fetal hydrops. The variant classification was then upgraded to class 4 likely pathogenic and reported as consistent with the diagnosis. This case demonstrates the importance of reporting these new gene/phenotypes in enabling others in the classification of variants, staying up-to-date with literature and following up phenotype for class 3 variants of interest.