Bart's Hydrops Fetalis Syndrome Research Articles

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.

Ten years' experience in prenatal diagnosis of α-thalassemia in a municipal hospital and retrospective analysis of ultrasonic abnormalities.

This study reviewed and analyzed the prenatal diagnosis experience of thalassemia in our center over the past decade and the abnormal ultrasonic characteristics of fetuses with hemoglobin (Hb) Bart's hydrops fetalis. Pregnant women and their partners who tested positive for α0-thalassemia or were diagnosed with thalassemia intermedia (HbH diseases) underwent genetic counseling, and a prenatal diagnostic procedure for α-thalassemia was recommended. Ultrasonography was performed before prenatal diagnosis. Invasive prenatal α-thalassemia diagnosis and ultrasonography were performed in 1049 patients at risk for Hb Bart's hydrops fetalis syndrome at our hospital from 2012 to 2021. Chorionic villus sampling (CVS) was performed in 58 cases (5.5%), amniocentesis in 902 cases (86%), and cordocentesis in 89 cases (8.5%). Hb Bart's hydrops fetalis syndrome was diagnosed in 280 fetuses. The most common body cavity effusion was pericardial effusion, ascites, and fetal systemic edema. The extensive experience at our center shows that carrier screening, molecular diagnostics, genetic counseling, and prenatal diagnosis are effective measures to prevent Hb Bart's hydrops fetalis syndrome. The ultrasonographic abnormalities in fetuses with Hb Bart's hydrops are mainly caused by an increase in cardiac output, which leads to the body cavity effusion from various organs.

Epidemiology of birth defects based on a birth defects surveillance system in southwestern China and the associated risk factors.

Birth defects (BDs) are associated with many potential risk factors, and its causes are complex. This study aimed to explore the epidemiological characteristics of BDs in Guangxi of China and the associated risk factors of BDs. BDs data of perinatal infants (PIs) were obtained from the Guangxi birth defects monitoring network between 2016 and 2020. Univariate Poisson regression was used to calculate the prevalence-rate ratios (PRR) to explore the changing trends of BDs prevalence by year and the correlation between the regarding of characteristics of BDs (including infant gender, maternal age, and quarter) and BDs. Clinical characteristics of PIs with BDs and general characteristics of their mothers were documented, and Spearman correlation analysis was used to explore the potential associated risk factors of BDs. Between 2016 and 2020, 44,146 PIs with BDs were monitored, with an overall BDs prevalence of 121.71 (95% CI: 120.58-122.84) per 10,000 PIs, showing a significant increase trend (PRR = 1.116, 95% CI: 1.108-1.123), especially the prevalence of congenital heart defects (CHDs) that most significantly increased (PRR = 1.300, 95% CI: 1.283-1.318). The 10 most common BDs were CHDs, polydactyly, congenital talipes equinovarus, other malformation of external ear, syndactyly, hypospadias, cleft lip with cleft palate, cleft lip, hemoglobin Bart's hydrops fetalis syndrome (BHFS), and congenital atresia of the rectum and anus. BDs were positively correlated with pregnant women's age (R = 0.732, P < 0.01) and education level (R = 0.586, P < 0.05) and having pre-gestational diabetes mellitus (PGDM)/gestational diabetes mellitus (GDM) (R = 0.711, P < 0.01), while when the pregnant women had a family history of a dead fetus (R = -0.536, P < 0.05) and a birth of a fetus with BDs (R = -0.528, P < 0.05) were negatively correlated with BDs. A significant increase in the prevalence of BDs was detected between 2016 and 2020 in Guangxi, especially the prevalence of CHDs that most significantly increased. Older maternal age, higher maternal education level, and having PGDM before pregnancy or GDM in early pregnancy were the risk factors for BDs.

Optimizing transfusion therapy for survivors of Haemoglobin Bart's hydrops fetalis syndrome: Defining the targets for haemoglobin-H fraction and "functional" haemoglobin level.

Owing to the unique pathophysiology of anaemia in haemoglobin Bart's hydrops fetalis (HBHF), a transfusion strategy based on beta-thalassemia guidelines is suboptimal for chronically transfused HBHF patients. A more aggressive transfusion aimed at reducing the proportion of non-functional HbH and improving the "functional" haemoglobin (f-Hb) can lead to reduced haemolysis and improved tissue oxygenation. However, the optimal transfusion targets for these parameters are not yet defined. In this retrospective, longitudinal study on four chronically transfused patients with HBHF, we used receiver operating characteristic curves to find a pre-transfusion f-Hb of 106g/l and a HbH of 16.1% to be the optimal thresholds to achieve a normal soluble transferrin receptor and lactate dehydrogenase, respectively.

Placental transcriptome sequencing combined with bioinformatics predicts potential genes and circular RNAs associated with hemoglobin Bart's hydrops fetalis syndrome.

Hemoglobin Bart's hydrops fetalis syndrome (BHFS) is the most severe form of α-thalassemia. Histological alternations can be observed in placenta, but placental transcriptome profile and circular RNAs have not been studied in this disease. The aim of this study was to define the placental transcriptional changes and find relevant circular RNAs in BHFS. We performed high-throughput RNA sequencing to detect placental samples from fetuses affected by BHFS (n=5) and normal fetuses (NF, n=5), quantitative reverse transcription polymerase chain reaction (RT-qPCR), and Sanger sequencing to validate the differentially expressed circRNAs and their potentially related miRNAs (BHFS, n=22; NF, n=11). Bioinformatics methods were performed for further analysis. Our results showed 152 differentially expressed genes (DEGs), 112 circRNAs, and 45 microRNAs that were differentially expressed. DEGs were found to be involved in Gene Ontology terms related to gas transport, cell adhesion, oxidative stress, organ development, hemopoiesis, and others. RT-qPCR results showed that hsa_circ_0003961 and hsa_circ_0006687 were upregulated (p < 0.05). The competing endogenous RNA and co-expression networks showed that hsa_circ_0003961 and hsa_circ_0006687 were connected with 3 miRNAs and some DEGs, including cell adhesion genes (e.g., CLDN19), hemoglobin related genes (e.g., SOX6 and HBZ) and angiogenesis related genes (e.g., EPHB2). Downregulations of hsa-miR-1299 and hsa-miR-625-5p in ceRNA network were also validated by RT-qPCR. Gene set enrichment analysis results for the two circRNAs showed that some gene sets associated with cell adhesion, hematopoietic system and apoptosis were significantly enriched. Our study characterized the placental transcriptome of BHFS. The circRNAs hsa_circ_0003961 and hsa_circ_0006687 in placenta may be relevant to BHFS.

Genotypes of thalassemia in children: an analysis of 30 417 cases.

To investigate the distribution of genotypes of thalassemia in children in Guangxi, China. A total of 30 417 children with positive results of thalassemia screening in the Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region from January 2011 to December 2019 were enrolled. Single-tube multiplex PCR, agarose gel electrophoresis, and reverse dot blot hybridization technique were used for the detection of common α- and β-thalassemia genes. Gap-PCR or gene sequence analysis was performed for 2 703 children suspected of rare thalassemia. Among the 30 417 children with positive results of thalassemia screening, 23 214 (76.32%) were diagnosed with thalassemia, and the detection rates of α-thalassemia, β-thalassemia, and α-thalassemia with β-thalassemia were 47.77%, 23.75%, and 4.80% respectively. A total of 13 types of α-thalassemia alleles (18 480 alleles in total) were detected, mainly --SEA (54.98%), including seven rare alleles, i.e., --THAI (0.43%), HKαα (0.02%), -α30 (0.01%), -α1.0 (0.01%), -α2.4 (0.01%), -α21.9 (0.01%), and HBA2:C272-279 del (0.01%). A total of 17 types of β-thalassemia alleles (9 168 alleles in total) were detected, mainly CD41-42 (47.79%), followed by CD17 (25.53%), including three rare alleles, i.e., IVS-II-5 (0.02%), IVS-I-2 (0.01%), and Gγ(Aγδβ)0 (0.01%). A total of 37 genotypes were detected in 14 531 children with α-thalassemia, among which the most common 6 genotypes were --SEA/αα (52.20%), -α3.7/αα (13.24%), αCSα/αα (7.52%), -α4.2 (6.06%), --SEA/-α3.7 (5.91%), and αWSα/αα (3.41%), accounting for 88.34%. A total of 49 genotypes were detected in 7 223 children with β-thalassemia, among which the most common 6 genotypes were CD41-42/βN (45.81%), CD17/βN (24.30%), IVS-II-654/βN (7.49%), -28/βN (5.62%), CD71-72/βN (4.42%), and CD26/βN (3.94%), accounting for 91.13%. A total of 137 genotypes were detected in 1 460 children with both α- and β-thalassemia, mainly --SEA/αα combined with CD41-42/βN (14.17%) and CD17/βN (8.35%). A total of 2 050 children were diagnosed with hemoglobin H disease (α0/α+), among whom 134 had β-thalassemia heterozygote and 12 had Bart hydrops fetalis syndrome (--SEA/--SEA); 355 children were diagnosed with β-thalassemia double heterozygote, and 128 were diagnosed with β-thalassemia homozygote, including 93 children with α-thalassemia. There are diverse gene mutations and rich genotypes of thalassemia among children in Guangxi, and α-thalassemia is more common, with --SEA/αα as the major genotype. There is a high proportion of children with both α- and β-thalassemia, and there are relatively high incidence rates of β-thalassemia double heterozygote and homozygote (intermedia and major).

Outcomes of allogeneic transplantation for hemoglobin Bart's hydrops fetalis syndrome in Hong Kong.

Hemoglobin Bart's hydrops fetalis syndrome (BHFS) was once considered a fatal condition universally. Medical advances over the past three decades have resulted in increasing numbers of BHFS survivors. This retrospective review summarized local territory-wide experience and outcomes of BHFS patients who received allogeneic hematopoietic stem cell transplantation (HSCT) in Hong Kong. All BHFS patients who underwent allogeneic HSCT in Hong Kong, either in one of the two former pediatric transplant centers (Queen Mary Hospital and Prince of Wales Hospital) on or before 2019 or in the single territory-wide pediatric transplant center (Hong Kong Children's Hospital) since 2019, from January 1, 1996, till December 31, 2020, were included. Basic demographic data, perinatal history, transplant details, long-term outcomes, and morbidities were reviewed. Total five allogeneic HSCT were performed in two males and three females at a median age of 22months, which include one 8/8 matched-sibling bone marrow transplant, one 5/6 matched-sibling cord blood transplant with HLA-DR antigenic mismatch, two 12/12 matched-unrelated peripheral blood stem cell transplant (PBSCT), and one haploidentical PBSCT with TCRαβ/CD45RA depletion from maternal donor. Neutrophil and platelet engrafted (>20×109 /L) at a median of 15 and 22days, respectively. All achieved near full donor chimerism at 1month. All patients survived and remained transfusion-independent without significant morbidities with median follow-up duration of 10years. To conclude, local data demonstrated favorable outcome of allogeneic HSCT for BHFS patients, but sample number is small. Non-directive approach in counseling and international collaboration is recommended.

The Clinical Severity of Alpha-2 Globin Gene Variants: Homozygosity for Hb Agrinio (HBA2: c.89T>C) Leads to Severe Antenatal Anemia, about 8 Cases in 3 Families

Introduction: Hemoglobin (Hb) Agrinio (HBA2: c.89T&amp;gt;C (Leu29Pro) mutation) is a rare highly unstable Hb variant resulting from a leucine to proline substitution at codon29 of the alpha2-globin gene. Eleven homozygous cases of this non-deletional alpha thalassemia were described in literature. Clinical course ranged from moderate (non-transfusion dependent anemia) to severe (transfusion dependent thalassemia). In addition, one probable case of Hb barts hydrops fetalis was also reported in a Greek series. Hb Agrinio was first described in individuals of Greek or Cypriot origins. Subsequently, some cases were reported among patients living in Spain and Macedonia, most often of Gypsy origin. We report here the clinical presentation of the 8 homozygous cases diagnosed by molecular biology analysis in France and underline the severity of the antenatal phenotype of the disease. Methods: Cases were identified by contacting all the French laboratories involved in the molecular diagnosis of hereditary red blood cell (RBC) disorders. Three different families were retrieved, including 8 pediatric homozygous cases diagnosed by alpha globin gene sequencing between 2006 and 2020. Standardized clinical and laboratory data were obtained from treatment centers. All parents gave their written consent for molecular analysis and their authorization for participating in this study. Results: Consanguinity was present in all 3 families, however no obvious link was found between the 3. Two originated from Spain (1 of gypsy origin) and 1 from Bulgaria. All patients were homozygous for the HBA2: c.89T&amp;gt;C mutation, without any additional beta or alpha anomalies using gene sequencing and MLPA. Main clinical presentation findings of homozygous patients are reported in the table. Among the 8 cases, there was one in utero death at 22 weeks GA and 7 living births. Three patients, the more anemic at birth, died during the first hours of life with a clinical picture of hydrops fetalis for 2 of them. Despite a normal cerebral doppler at 32 weeks of GA, the third newborn (II2), presented at birth with a blueberry syndrome with cutaneous and hepatic extramedullary hematopoiesis, severe pulmonary arterial hypertension and Hb value of 6 g/dl, leading to neonatal death. Among the 4 survivor patients, one (III3), diagnosed in the antenatal period, benefited from in utero transfusions (TF) administered at 23 and 27 weeks because an accelerated middle cerebral artery peak systolic velocity of 52cm/s was measured. Hypospadias with ambiguous genitalia requiring surgical treatment was present in one patient and micropenis treated medically and undescended testis in a second one. All survivors (n=4/8) are currently under regular TF and chelation therapy. TF were generally (3/4) occasional in the first years of life and then became regular (&amp;gt;8 TF/year) later in childhood (at 6, 6, 7 years of age respectively). Conclusions: our national experience of homozygous Hb Agrinio cases revealed a more severe clinical course than reported in literature, with clinical presentation ranging from alpha-thalassemia major (Hb Barts hydrops fetalis) to severe non deletional HbH disease. Antenatal anemia was profound. In utero or neonatal deaths concerned half of the patients and additional ones were, even not biologically confirmed, also found in the family histories. Of note, congenital urogenital abnormalities similar to those found in the classical Hb Bart's Hydrops FetalisSyndrome were found in 2 patients. This up to now unreported severity could be explained by a closer monitoring and a more comprehensive clinical study of the cases/siblings allowing the antenatal period to be better described. The existence of aggravating genetic factor is another hypothesis and NGS analysis of genes involved in RBC disorders is planned. In couples at risk for homozygous Hb Agrinio, early genetic counseling and prenatal diagnosis should be offered. If the pregnancy is continued, a very close fetal ultrasound monitoring is mandatory and intrauterine TFs can be administered when severe fetal anemia is detected. Table Disclosures Thuret: Celgene: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; Novartis pharma: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; bluebird bio, Inc.: Membership on an entity's Board of Directors or advisory committees, Other: Investigator in clinical trials; Apopharma: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Noninvasive Prenatal Detection of Hemoglobin Bart Hydrops Fetalis Via Maternal Plasma Dispensed With Parental Haplotyping Using the Semiconductor Sequencing Platform

(Abstracted from Am J Obstet Gynecol 2020;222:185.e1–185.e17) Hemoglobin Bart's hydrops fetalis syndrome (Hb Bart's) is a common inherited genetic disease in the south of China and Southeast Asia. Couples who are both carriers of the Southeast Asian type of α-thalassemia gene deletion have a 25% risk of having a pregnancy affected with Hb Bart's as a result of autosomal recessive inheritance.

Clinical practice guidelines for alpha-thalassemia

Alpha-thalassemia is an autosomal recessive genetic disease as well as a relatively common hemoglobinopathy. Severe alpha-thalassemia (also known as Hb Bart's Hydrops fetalis syndrome) and intermediate alpha-thalassemia (also known as Hb H disease) are among the most common birth defects in southern China. To implement carrier screening and large population prevention program in high incidence areas can significantly reduce the incidence of alpha-thalassemia. This guideline was established by combining the discoveries of basic research, clinical research and guidelines from other countries and the actual data of Chinese population. It has summarized the medical genetics knowledge and key points in the clinical treatment for alpha-thalassemia, and provided suggestions for the clinical diagnosis and standard management of patients.

Noninvasive prenatal detection of hemoglobin Bart hydrops fetalis via maternal plasma dispensed with parental haplotyping using the semiconductor sequencing platform

Thalassemia is one of the most common monogenetic diseases in the south of China and Southeast Asia. Hemoglobin Bart's hydrops fetalis syndrome was caused by a homozygous Southeast Asian deletion (-/-) in the HBA gene. Few studies have proved the potential of screen for Bart's hydrops fetalis using fetal cell-free DNA. However, the number of cases is still relatively small. Clinical trials of large samples would be needed. In this study, we aimed to develop a noninvasive method of target-captured sequencing and genotyping by the Bayesian method using cell-free fetal DNA to identify the fetal genotype in pregnant women who are at risk of having hemoglobin Bart hydrops fetalis in a large-scale study. In total, 192,173 couples from 30 hospitals were enrolled in our study and 878 couples were recruited, among whom both the pregnant women and their husbands were detected to be carriers of Southeast Asian type (-/αα) of α-thalassemia. Prenatal diagnosis was performed by chorionic villus sampling, amniocentesis, or cordocentesis using gap-polymerase chain reaction considered as the golden standard. As a result, we found that the sensitivity and specificity of our noninvasive method were 98.81% and 94.72%, respectively, in the training set as well as 100% and 99.31%, respectively, in the testing set. Moreover, our method could identify all of 885 maternal samples with the Southeast Asian carrier and 36 trisomy samples with 100% of sensitivity in T13, T18, and T21 and 99.89% (1 of 917) and 99.88% (1 of 888) of specificity in T18 and T21, respectively. Our method opens the possibility of early screening for maternal genotyping of α-thalassemia, fetal aneuploidies in chromosomes 13/18/21, and hemoglobin Bart hydrops fetalis detection in 1 tube of maternal plasma.

Potential new approaches to the management of the Hb Bart's hydrops fetalis syndrome: the most severe form of α-thalassemia.

The α-thalassemia trait, associated with deletions removing both α-globin genes from 1 chromosome (genotype ζ αα/ζ--), is common throughout Southeast Asia. Consequently, many pregnancies in couples of Southeast Asian origin carry a 1 in 4 risk of producing a fetus inheriting no functional α-globin genes (ζ--/ζ--), leading to hemoglobin (Hb) Bart's hydrops fetalis syndrome (BHFS). Expression of the embryonic α-globin genes (ζ-globin) is normally limited to the early stages of primitive erythropoiesis, and so when the ζ-globin genes are silenced, at ∼6 weeks of gestation, there should be no α-like globin chains to pair with the fetal γ-globin chains of Hb, which consequently form nonfunctional tetramers (γ4) known as Hb Bart's. When deletions leave the ζ-globin gene intact, a low level of ζ-globin gene expression continues in definitive erythroid cells, producing small amounts of Hb Portland (ζ2γ2), a functional form of Hb that allows the fetus to survive up to the second or third trimester. Untreated, all affected individuals die at these stages of development. Prevention is therefore of paramount importance. With improvements in early diagnosis, intrauterine transfusion, and advanced perinatal care, there are now a small number of individuals with BHFS who have survived, with variable outcomes. A deeper understanding of the mechanism underlying the switch from ζ- to α-globin expression could enable persistence or reactivation of embryonic globin synthesis in definitive cells, thereby providing new therapeutic options for such patients.

Molecular characterization of Hb H disease in southern Thailand.

Genotypes of 260 individuals with hemoglobin H (Hb H) disease originating from various provinces in southern Thailand were characterized by multiplex PCR (M-PCR) and reverse dot blot hybridization (RDB). M-PCR was used to amplify target fragments and then hybridized with allele-specific oligonucleotide (ASO) probes which were bound on a nylon membrane. A total of eight α-thalassemia (α-thal) mutations, which produced eight Hb H disease genotypes (α0-thal/α+-thal), were detected. The most common form of α0-thal was -SEA with a frequency of 99.23%. The other form (0.77%) of α0-thal mutation was a THAI deletion (-THAI). The deletional α+-thal mutations comprised 3.7kb (-α3.7) and 4.2kb (-α4.2) deletions which were found in 172 (66.15%) and 5 (1.92%) alleles, respectively. The incidence of non-deletional α+-thal in decreasing order was Hb Constant Spring (Hb CS, αCS) 28.85%, Hb Quong Sze (Hb QS, αQS) 1.54%, and Hb Paksé (Hb PS, αPS) 0.77%. The genotype characterization of Hb H disease and the development of the RDB technic for detection of α-thal mutations presented in this study enable the prenatal diagnosis of Hb Bart's hydrops fetalis syndrome.

Invasive prenatal diagnosis of α-thalassemia to control Hb Bart's hydrops fetalis syndrome: 15years of experience.

The aim of the present study was to report experiences with invasive prenatal diagnosis of α-thalassemia for the prevention of Hb Bart's hydrops fetalis syndrome in the Guangxi Zhuang Autonomous Region, China. Pregnant women and their partners who tested positive for α0-thalassemia or were diagnosed with HbH diseases were counseled and suggested to undergo a prenatal diagnostic procedure for α-thalassemia. Fetal material was obtained by chorionic villus sampling (CVS) between 9 and 13weeks of gestation, by amniocentesis between 16 and 24weeks of gestation and by cordocentesis after 24weeks of gestation. The α0-thalassemia gene types were detected by gap polymerase chain reaction (Gap-PCR). All results were finally confirmed by DNA analysis after delivery or termination of pregnancy. An invasive prenatal α-thalassemia diagnosis was performed in 3155 cases at risk for Hb Bart's hydrops fetalis syndrome at our hospital from 2002 to 2016. CVS was performed in 1559 cases (49.4%), amniocentesis in 1240 cases (39.3%) and cordocentesis in 356 cases (11.3%). In total, 786 fetuses were diagnosed as Hb Bart's hydrops fetalis syndrome. Among these cases, the α-thalassemia genotype was --SEA/--SEA in 784 cases and --SEA/--THAI in 2 cases. All affected pregnancies were terminated in time. This extensive experience suggests that carrier screening, molecular diagnostics, genetic counselling, and prenatal diagnosis are effective measures to prevent Hb Bart's hydrops fetalis syndrome.

Outcomes and morbidities of patients who survive haemoglobin Bart's hydrops fetalis syndrome: 20-year retrospective review.

Haemoglobin Bart's hydrops fetalis syndrome was once considered a fatal condition. However, advances over the past two decades have enabled survival of affected patients. Data relating to their morbidities and outcomes will help medical specialists formulate a management plan and parental counselling. All babies with the syndrome who survived beyond the neonatal period and were subsequently managed long-term in eight public hospitals in Hong Kong from 1 January 1996 to 31 December 2015 were included. Patient and parent characteristics, antenatal care, reasons for continuation of pregnancy, intrauterine interventions, perinatal course, presence of congenital malformations, stem-cell transplantation details, and long-term neurodevelopmental outcomes were reviewed. A total of nine patients were identified, of whom five were female and four male. The median follow-up duration was 7 years. All were Chinese and were homozygous for the Southeast Asian α-thalassaemia deletion. Five of the nine mothers received antenatal care at a public hospital and opted to continue the pregnancy after antenatal diagnosis and counselling. Despite intrauterine transfusions, all babies were born with respiratory depression and required intubation and mechanical ventilation during the neonatal period. Hypospadias was identified in all four male infants. Growth retardation, global developmental delay, and residual neurological deficits were noted in two-thirds of the patients. Haematopoietic stem-cell transplantation was performed in two patients, who became transfusion-independent. Survival of patients with Bart's hydrops fetalis syndrome is possible but not without short- and long-term complications; local epidemiology is comparable to that documented for an international registry. Detailed antenatal counselling of parents with a non-judgemental attitude and cautious optimism are imperative.

Prenatal diagnosis of Thailand deletion of α-thalassemia 1 families

To conduct analysis and prenatal diagnosis on 11 couples carrying Thailand deletion (--(THΑI)) α-thalassemia 1, so as to provide information for clinical genetic counseling on α-thalassemia 1. Altogether 11 Thailand deletion (--(THΑI)) α-thalassemia 1 families were collected from Fujian Maternal and Children Health Hospital from May 2009 to September 2015. Gap-polymerase chain reaction (gap-PCR) and reverse dot blot (RDB) technology were used to detect the thalassemia mutations in the couples and fetuses. In one family, Thailand deletion α-thalassemia 1 was detected in both the pregnant woman and her husband. In 10 families, Thailand deletion α-thalassemia 1 was detected in either the pregnant women or the husband, while the spouses had α-thalassemia heterozygote (1 combined with β thalassemia heterozygote). Thailand deletion α-thalassemia 1 family members all had lower mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH). In prenatal diagnosis of the 12 fetuses, 4 fetuses were found with hemoglobin(Hb) Bart's hydrops fetalis syndrome, 5 were with α-thalassemia heterozygote, and 3 were normal. For couples with positive hematological phenotype but normal results in routine genetic examination of α-thalassemia, attention should be paid especially for with a history of having babies of hydrops fetalis syndrome or hemoglobin H disease. It is necessary to consider the possibility of the rare Thailand deletion (--(THΑI)) α-thalassemia 1. Prenatal diagnosis for high-risk families plays an important role.

Single-tube nonaplex microsatellite PCR panel for preimplantation genetic diagnosis of Hb Bart's hydrops fetalis syndrome.

To develop a single-tube multi-marker assay for improved preimplantation genetic diagnosis (PGD) of deletional and/or non-deletional Hb Bart's hydrops fetalis syndrome, providing haplotype confirmation of deletional status, and maximization of linkage informativity. We performed in silico mining to identify novel microsatellites within 1 Mb flanking the alpha-globin gene cluster, and optimized a single-tube assay combining detection of α(0) -thalassemia deletions with multi-marker linkage analysis. We performed validation on 100 single cells prior to clinical PGD application. Of 42 markers encompassing the α-globin gene cluster that were identified in silico, 9 were highly polymorphic (0.68 ≤ polymorphism information content ≤ 0.92; 0.66 ≤ Ho ≤ 0.90; 10 ≤ alleles ≤ 35) and optimized to co-amplify directly from a single cell. A validation analysis of 100 single lymphoblasts yielded 100% amplification success for all markers, and individual marker allele drop-out (ADO) rates of 0-5%. Clinical application of the assay in PGD for Hb Bart's (2 cases/cycles) resulted in a twin pregnancy and healthy live birth of two baby girls. This single-tube nonaplex microsatellite PCR panel can be applied directly to PGD of most deletional Hb Bart's without the need for deletion-specific customization, and to linkage-based PGD of non-deletional Hb Bart's.

Weighing the Evidence for Newborn Screening for Hemoglobin H Disease

To conduct a systematic review to assist the United States Secretary of Health and Human Services Advisory Committee on Heritable Disorders in Newborns and Children (SACHDNC) to determine whether Hemoglobin H screening should be included among the core recommended conditions for newborn screening. We identified 21 articles in MEDLINE from 1989 to March 2010 that provided evidence regarding screening, treatment, and outcomes associated with Hemoglobin H disease. In California, newborn screening has identified 9 cases per 100 000 of deletional hemoglobin H disease and 0.6 cases per 100 000 of nondeletional hemoglobin H disease. Five cases of hemoglobin Bart's hydrops fetalis syndrome were also identified in over ten years of screening for Hemoglobin H disease. Although Hemoglobin H disease is associated with a wide range of morbidity, no studies were found that evaluated the benefits of early identification and treatment. The SACHDNC found the data insufficient to recommend that states adopt newborn screening for Hemoglobin H disease.

Simplified PGD of common determinants of haemoglobin Bart’s hydrops fetalis syndrome using multiplex-microsatellite PCR

The high incidence of double-gene deletions in α-thalassaemia increases the risk of having pregnancies with homozygous α(0)-thalassaemia, the cause of the lethal haemoglobin (Hb) Bart's hydrops fetalis syndrome. Preimplantation genetic diagnosis (PGD) has played an important role in preventing such cases. However, the current gap-PCR based PGD protocol for deletional α-thalassaemia requires specific primer design for each specific deletion. A universal PGD assay applicable to all common deletional determinants of Hb Bart's hydrops fetalis syndrome has been developed. Microsatellite markers 16PTEL05 and 16PTEL06 within the α-globin gene cluster were co-amplified with a third microsatellite marker outside the affected region in a multiplex-PCR reaction and analysed by capillary electrophoresis. Eight informed couples at risk of having Hb Bart's hydrops fetalis were recruited in this study and all patients underwent standard procedures associated with IVF. A total of 47 embryos were analysed. Three pregnancies were achieved from three couples, with the births of two healthy babies and one ongoing pregnancy. This work has successfully adapted an earlier protocol and developed a simple and reliable single-cell assay applicable to PGD of Hb Bart's hydrops fetalis syndrome regardless of type of deletion. Alpha-thalassaemia is one of the most common inheritable disorders worldwide. It is a blood disorder that, in its lethal form caused by deletion of all four copies of the α-globin gene, results in the demise of the affected fetus, a condition referred to as haemoglobin (Hb) Bart's hydrops fetalis syndrome. Preimplantation genetic diagnosis (PGD) has played an important role in preventing such cases. Current PGD protocols for deletional α-thalassaemia utilize a strategy called gap-PCR, which requires the different assays for different deletion types. We have developed a universal PGD assay applicable to all common deletional determinants of Hb Bart's hydrops fetalis syndrome based on microsatellite marker analysis. Eight informed couples at risk of having Hb Bart's hydrops fetalis were recruited in this study and all patients underwent standard procedures associated with IVF. Forty-five embryos were analysed in total. Three pregnancies were achieved from three couples, with the births of two healthy babies and one pregnancy still ongoing. We have successfully adapted our earlier protocol and developed a simple and reliable single cell assay applicable to PGD of Hb Bart's hydrops fetalis syndrome regardless of the type of deletion.

Homozygosity for the Mediterranean α-thalassemic deletion (hemoglobin Barts hydrops fetalis)

Hemoglobin Barts hydrops fetalis syndrome is the most severe and generally fatal clinical phenotype of α-thalassemia. We diagnosed a fetus at 23-weeks gestation with having hydrops fetalis, by ultrasound. At 32 weeks, intrauterine death was detected. Molecular studies revealed that the fetus had the hemoglobin Barts hydrops fetalis syndrome due to homozygosity for the Mediterranean α-thalassemia deletion. This clinical phenotype is generally rare in the Eastern Mediterranean, and this is the first report of this syndrome from Iraq. Techniques for molecular characterization became available only very recently in this country, in a diagnostic setting. Thus, the detection of further cases might be expected in future.