Hb H hydrops foetalis syndrome: a case report and review of literature

The Clinical Phenotypes of Alpha Thalassemia

Clinical manifestations of α-thalassemia range from no symptoms to severe transfusion-dependent anemia. Alpha thalassemia trait is deletion of 1 to 2 α-globin genes, whereas α-thalassemia major (ATM; Barts hydrops fetalis) is the deletion all 4 α genes. All other genotypes of intermediate severity are categorized as HbH disease, a vastly heterogenous group. Clinical spectrum is classified as mild, moderate, and severe by symptoms and need for intervention. Anemia in prenatal period may be fatal without intrauterine transfusions. New therapies to modify HbH disease or provide cure for ATM are under development.

Molecular Basis and Genetic Modifiers of Thalassemia

Thalassemia syndromes are common monogenic disorders and represent a significant health issue worldwide. In this review, the authors elaborate on fundamental genetic knowledge about thalassemias, including the structure and location of globin genes, the production of hemoglobin during development, the molecular lesions causing α-, β-, and other thalassemia syndromes, the genotype-phenotype correlation, and the genetic modifiers of these conditions. In addition, they briefly discuss the molecular techniques applied for diagnosis and innovative cell and gene therapy strategies to cure these conditions.

DeepThal: A Deep Learning-Based Framework for the Large-Scale Prediction of the α+-Thalassemia Trait Using Red Blood Cell Parameters

Objectives: To develop a machine learning (ML)-based framework using red blood cell (RBC) parameters for the prediction of the α+-thalassemia trait (α+-thal trait) and to compare the diagnostic performance with a conventional method using a single RBC parameter or a combination of RBC parameters. Methods: A retrospective study was conducted on possible couples at risk for fetus with hemoglobin H (Hb H disease). Subjects with molecularly confirmed normal status (not thalassemia), α+-thal trait, and two-allele α-thalassemia mutation were included. Clinical parameters (age and gender) and RBC parameters (Hb, Hct, MCV, MCH, MCHC, RDW, and RBC count) obtained from their antenatal thalassemia screen were retrieved and analyzed using a machine learning (ML)-based framework and a conventional method. The performance of α+-thal trait prediction was evaluated. Results: In total, 594 cases (female/male: 330/264, mean age: 29.7 ± 6.6 years) were included in the analysis. There were 229 normal controls, 160 cases with the α+-thalassemia trait, and 205 cases in the two-allele α-thalassemia mutation category, respectively. The ML-derived model improved the diagnostic performance, giving a sensitivity of 80% and specificity of 81%. The experimental results indicated that DeepThal achieved a better performance compared with other ML-based methods in terms of the independent test dataset, with an accuracy of 80.77%, sensitivity of 70.59%, and the Matthews correlation coefficient (MCC) of 0.608. Of all the red blood cell parameters, MCH < 28.95 pg as a single parameter had the highest performance in predicting the α+-thal trait with the AUC of 0.857 and 95% CI of 0.816−0.899. The combination model derived from the binary logistic regression analysis exhibited improved performance with the AUC of 0.868 and 95% CI of 0.830−0.906, giving a sensitivity of 80.1% and specificity of 75.1%. Conclusions: The performance of DeepThal in terms of the independent test dataset is sufficient to demonstrate that DeepThal is capable of accurately predicting the α+-thal trait. It is anticipated that DeepThal will be a useful tool for the scientific community in the large-scale prediction of the α+-thal trait.

Clinical and genetic characteristics of hemoglobin H disease in Iran

Hemoglobin H (Hb H) disease is a subtype of α-thalassemia caused by deletional and/or non-deletional mutations in three alpha-globin genes in which the various genotypes determine the disease severity. This study was aimed to investigate the frequency of alpha gene mutations and genotypes and their correlation with hematological and clinical characteristics in Iran. Among 202 patients diagnosed with Hb H disease through a national study in Iran according to standard methods, we had access to the hematologic and clinical findings and genetic data of 101 patients in whom genetic study was performed. Genomic DNA from peripheral blood was extracted and analyzed for identification of α-globin gene mutations using Multiplex Gap Polymerase Chain Reaction, Reverse Hybridization Assay, and finally Direct DNA Sequencing method. Twenty-one different mutations and thirty genotypes were detected in 101 patients with Hb H disease. In total, 39 patients (38.6%) were deletional and 62 patients (61.4%) were non-deletional type of the disease. The _--^MED mutation was highly prevalent in almost half of the patients (56.4%). Among various genotypes, -^MED/-a^3.7 (29.7%) and -α^20.5/-α^5NT (6.9%) were the most prevalent genotypes found in the studied group. Patients with non-deletional type presented with more severe hematological and clinical findings. Hb H percentage and serum ferritin levels were significantly higher in non-deletional patients in comparison to the deletional group (p < 0.05). 12 (11.9%) and 40 (39.6%) out of 101 patients were on regular and occasional transfusions, respectively. 83% of those with regular transfusion belonged to the non-deletional group. Among transfusion-dependent patients, -^MED/α^CSα and α^20.5/-α^5NT were the most common genotypes. In this study, two patients with -α^20.5/α^CSα and -^MED/α^-5NT genotypes experienced thrombotic events. This study indicated that although non-deletional genotypes of Hb H disease were responsible for more clinical severity of the disease, due to the presence of severe phenotypes even in deletional types, no definite correlation was found between genotype and phenotype.

Detection of maternal carriers of common α-thalassemia deletions from cell-free DNA

α-Thalassemia is a common inherited blood disorder manifested mainly by the deletions of α-globin genes. In geographical areas with high carrier frequencies, screening of α-thalassemia carrier state is therefore of vital importance. This study presents a novel method for identifying female carriers of common α-thalassemia deletions using samples routinely taken for non-invasive prenatal tests for screening of fetal chromosomal aneuploidies. A total of 68,885 Vietnamese pregnant women were recruited and α-thalassemia statuses were determined by gap-PCR, revealing 5344 women (7.76%) carried deletions including αα/--SEA (4.066%), αα/-α3.7 (2.934%), αα/-α4.2 (0.656%), and rare genotypes (0.102%). A two-stage model was built to predict these α-thalassemia deletions from targeted sequencing of the HBA gene cluster on maternal cfDNA. Our method achieved F1-scores of 97.14-99.55% for detecting the three common genotypes and 94.74% for detecting rare genotypes (-α3.7/-α4.2, αα/--THAI, -α3.7/--SEA, -α4.2/--SEA). Additionally, the positive predictive values were 100.00% for αα/αα, 99.29% for αα/--SEA, 94.87% for αα/-α3.7, and 96.51% for αα/-α4.2; and the negative predictive values were 97.63%, 99.99%, 99.99%, and 100.00%, respectively. As NIPT is increasingly adopted for pregnant women, utilizing cfDNA from NIPT to detect maternal carriers of common α-thalassemia deletions will be cost-effective and expand the benefits of NIPT.

A Novel Homozygous Missense Mutation of PIEZO1 Leading to Lymphatic Malformation-6 Identified in a Family With Three Adverse Pregnancy Outcomes due to Nonimmune Fetal Hydrops

Lymphatic malformation-6 (LMPHM6) is a rarer form of nonimmune hydrops that often manifests as widespread lymphedema involving all segments of the body, namely, subcutaneous edema, intestinal/pulmonary lymphangiectasia, chylothoraces, and pleural/pericardial effusions. Here, we detected one rare and previously unobserved homozygous missense variant in PIEZO1 (c.5162C&gt;G, p.Ser1721Trp) as a novel genetic cause of autosomal recessive LMPHM6, in a family with three adverse pregnancy outcomes due to nonimmune fetal hydrops. Although, the loss-of-function mutations such as those usually including nonsense, frameshift, splice site, and also fewer missense variants in PIEZO1 have been proved to lead to LMPHM6, among these, the biallelic homozygous mutations resulting in the loss of function of PIEZO1 have not been reported before. Here, we first strongly implicated impaired PIEZO1 function–associated LMPHM6 with a homozygous missense mutation in PIEZO1.

Description of Hb Évora (HBA2: c.106T>C) on an Unexpected Allele in a Swiss Family

α-Thalassemia (α-thal) is caused by DNA deletions or point mutations in the genes coding for the α-globin chains and can lead to hemolytic anemia in its carriers. If only one of the four α genes is affected, the mutation is mostly discovered by chance, as the carriers are asymptomatic. Hb Évora (HBA2: c.106T>C) is an Hb variant that leads to such an α-thal trait (α^Tα/αα) and thus, to mild microcytic hypochromic anemia. The mutation was first reported in 2001 and named Hb Évora in 2007 (based on the geographic origin of one of the studied families). It was found in four unrelated families originating from Portugal and the Philippines. We now report the discovery of Hb Évora not only in a proband with no known ancestors from either country, but also on an unexpected allele. Subsequently, her close relatives were studied, revealing the same mutation in her brother. No clear correlation between phenotype and genotype was observed.

Clinical Classification, Screening and Diagnosis for Thalassemia

At present, thalassemia diseases are classified into transfusion-dependent thalassemia and non-transfusion-dependent thalassemia. This classification is based on the clinical severity of patients determining whether they do require regular blood transfusions to survive (transfusion-dependent thalassemia) or not (non-transfusion-dependent thalassemia). In addition to the previous terminology of "thalassemia major" or "thalassemia intermedia," this classification has embraced all other forms of thalassemia syndromes such as α-thalassemia, hemoglobin E/β-thalassemia and combined α- and β-thalassemias. Definitive diagnosis of thalassemia and hemoglobinopathies requires a comprehensive workup from complete blood count, hemoglobin analysis, and molecular studies to identify mutations of globin genes.

Fetal Anemia Causing Hydrops Fetalis From an Alpha-Globin Variant: Homozygous Hemoglobin Constant Spring

BACKGROUND

Fetal anemia is often assumed to be due to red cell alloimmunization and Parvovirus infection, and can lead to hydrops fetalis and death in utero. Other causes, such as mutations of hemoglobin alpha, are less commonly considered.

METHODS

We report 7 cases with fetal anemia causing hydrops fetalis. Serial Doppler ultrasound for measurement peak systolic velocity (PSV) of middle cerebral artery (MCA) was used for evaluation of fetal anemia. Fetal anemia is suggested if the MCA/PSV ratio is >1.5 multiple of median. Cordocentesis was performed subsequently to find the cause of fetal anemia and check fetal hemoglobin for consideration of intrauterine infusion. Investigations for fetal anemia include complete blood count, blood morphology, and blood group of mother and fetus, reticulocyte counts, red cell indices, screening for thalassemia, hemoglobin typing, acid elution test, parvovirus B 19 serology, and TORCH titer (toxoplasmosis, rubella, cytomegalovirus, herpes simplex virus, human immunodeficiency virus, and syphilis). Intrauterine infusion, using irradiated prestorage filtered red cell with hematocrit level of 80%, is indicated if fetal hemoglobin is <10 g/dL.

RESULT

Seven cases with fetal anemia were prenatally diagnosed from gestational ages 20 to 34 weeks. Initial hematocrit in these cases varied from 9% to 17.2%. In each case, causes of anemia were determined using the investigations listed above. All cases underwent uneventfully up to 3 intrauterine transfusions. DNA study for thalassemia demonstrated homozygous Constant Spring (CS) in 5 cases, homozygous CS with heterozygous E in 1 case, and compound heterozygous CS and Pakse in 1 case. The perinatal outcomes were normal term in 5 cases, preterm in 2 cases. Low birth weight was determined in 2 cases. The screening for thalassemia major, including the osmotic fragility and dichlorophenol indophenol precipitation test (DCIP), is not helpful for detecting hemoglobin variants such as Constant Spring or Pakse.

SUMMARY

This study emphasizes homozygous Constant Spring and compound heterozygous CS and Pakse as a cause of hydrops fetalis. Proper management for the fetus after diagnosis can lead to a good fetal outcome. Prevention control programs should include screening of parents for the heterozygous state.

Sonographic markers of fetal α-thalassemia major

α-Thalassemia prevails in Southeast Asia, where α-thalassemia major is a lethal type. Sonography is a helpful and cost-effective screening tool for detecting α-thalassemia major fetuses. The cardiothoracic ratio, placental thickness, and middle cerebral artery peak systolic velocity are most used in clinical practice. These sensitive markers are helpful for evaluation of the hemodynamic status and cardiovascular function of the affected fetuses. They can predict fetal α-thalassemia major and assess the efficacy of treatment noninvasively; therefore, the medical costs as well as the possibility of fetal loss caused by invasive procedures can be reduced. Other potentially useful sonographic markers need further studies, although previous preliminary research suggests their usefulness. This article will review those sonographic markers.

Clinical manifestations of α-thalassemia

α-Thalassemia mutations affect up to 5% of the world's population. The clinical spectrum ranges from an asymptomatic condition to a fatal in utero disease. Hemoglobin H disease results from mutations of three α-globin genes. Deletional forms result in a relatively mild anemia, whereas nondeletional mutations result in a moderate to severe disease characterized by ineffective erythropoiesis, recurrent transfusions, and growth delay. Hemosiderosis develops secondary to increased iron absorption, as well as transfusion burden. Hemoglobin Bart's hydrops fetalis is usually a fatal in utero disease caused by the absence of α genes. Population screening to identify at-risk couples is essential. Affected pregnancies result in severe fetal and maternal complications. Doppler ultrasonography with intrauterine transfusion therapy may improve the fetal prognosis but creates ethical challenges for the family and health providers.

The molecular basis of α-thalassemia

The globin gene disorders including the thalassemias are among the most common human genetic diseases with more than 300,000 severely affected individuals born throughout the world every year. Because of the easy accessibility of purified, highly specialized, mature erythroid cells from peripheral blood, the hemoglobinopathies were among the first tractable human molecular diseases. From the 1970s onward, the analysis of the large repertoire of mutations underlying these conditions has elucidated many of the principles by which mutations occur and cause human genetic diseases. This work will summarize our current knowledge of the α-thalassemias, illustrating how detailed analysis of this group of diseases has contributed to our understanding of the general molecular mechanisms underlying many orphan and common diseases.

Advances in the treatment of alpha-thalassemia

Alpha (α)-thalassemia represents a group of recessively inherited hemoglobin disorders marked by deficient or absent synthesis of 1 to all 4 of the α-globin genes. Inactivation of 3 α-globin genes--either by deletional or nondeletional mutations--results in hemoglobin H (Hb H) disease. Patients with Hb H disease produce hemoglobin composed of all beta chains and have moderate to severe hemolytic anemia, a variable degree of ineffective erythropoiesis, and splenomegaly. Transfusion requirements vary depending on the mutation and clinical severity. Treatment for deletional Hb H disease is primarily preventative and transfusions are uncommon. Patients with nondeletional Hb H disease (e.g., Hb H Constant Spring) typically have more severe anemia, and approximately one-third require regular transfusions. These patients often require comprehensive, multidisciplinary care. This chapter focuses on screening, diagnosis, and treatment approaches for patients with Hb H disease.

The contribution of extramedullary hematopoiesis to hepatomegaly in anemic hydrops fetalis: a study in alpha-thalassemia hydrops fetalis

Massive hepatomegaly is a common finding in hydrops fetalis (HF) arising from hemoglobinopathies. It has been suggested that extramedullary hematopoiesis, which is markedly increased in response to anemia, plays a principal role in hepatomegaly via sinusoidal obstruction and distortion of the intrahepatic architecture. To test this concept, the authors compared 20 cases of α-thalassemia (hemoglobin Bart, 15 cases; hemoglobin H, 5 cases) with 19 cases of HF arising from other causes and 39 control nonhydrops cases. The mean liver weight in α-thalassemia cases was significantly heavier than in control cases and in hydrops fetalis cases due to other causes (P < 0.01). This was not explainable on the basis of extramedullary hematopoiesis (erythropoiesis or myelopoiesis) or hemosiderin deposition, since cases of HF from other causes, especially related to anemia, showed similar findings to α-thalassemia cases. While these processes no doubt contribute to hepatic weight, the major factor would still be high-output cardiac failure causing hepatic congestion.

HbE/β-thalassemia: basis of marked clinical diversity

Hemoglobin E thalassemia accounts for about one-half of all cases of severe beta thalassemia. There is marked variability in its clinical severity ranging from an asymptomatic to a transfusion-dependent phenotype. The phenotypic variability and inadequate longitudinal data present challenges in determining the optimal management of patients. This article summarizes findings on the natural history of Hemoglobin E thalassemia and some factors responsible for its clinical heterogeneity. Major genetic factors include the type of beta thalassemia mutation, the co-inheritance of alpha thalassemia, and polymorphisms associated with increased synthesis of fetal hemoglobin. Other factors, including response to anemia, and the influence of infection with malaria and other environmental influences, may be important. The remarkable variation and instability of clinical phenotypes in Hemoglobin E thalassemia require individual management plans for each patient, which should be reassessed over time.

The molecular basis of α-thalassemia: a model for understanding human molecular genetics

Down-regulation of α-globin synthesis causes α-thalassemia with underproduction of fetal (HbF, α(2)γ(2)) and adult (HbA, α(2)β(2)) hemoglobin. This article focuses on the human α-globin cluster, which has been characterized in great depth over the past 30 years. In particular the authors describe how the α genes are normally switched on during erythropoiesis and switched off as hematopoietic stem cells commit to nonerythroid lineages. In addition, the principles by which α-globin expression may be perturbed by natural mutations that cause α-thalassemia are reviewed.

Complexity of alpha thalassemia: growing health problem with new approaches to screening, diagnosis, and therapy

Alpha thalassemia, the most common genetic disorder of hemoglobin synthesis, affects up to 5% of the world's population. It represents a group of conditions with reduced or absent synthesis of one to all four of alpha globin genes. Deletional or nondeletional mutations occur on chromosome 16. Its severity ranges from asymptomatic to fatal in utero. Hemoglobin H disease, a mutation of three alpha globin genes, is more severe than previously recognized. Anemia, hypersplenism, hemosiderosis, growth failure, and osteoporosis are commonly noted as the patient ages. Alpha thalassemia major, a usually fatal in utero disease, is now recognized to have a complex molecular and phenotypic expression with increasing births being reported. Surviving newborns without intrauterine transfusion often have congenital anomalies and neurocognitive injury. Serious maternal complications often accompany pregnancy. Doppler ultrasonography with intrauterine transfusion ameliorates these complications. The high incidence in many populations mandates population screening and prenatal diagnosis of at-risk couples. Universal newborn screening has been adopted in several regions with DNA confirmatory testing. These advances have resulted in ethical dilemmas for the family and the provider.

Hydrops fetalis in the stillborn: a series from the central region of Thailand

The purpose of this study was to analyze the cause of hydrops fetalis (HF) among fetal deaths in the central region of Thailand. Autopsy reports diagnosed as HF from 1999 to 2008 at King Chulalongkorn Memorial Hospital were retrieved, and the pathologic findings, clinical information, fetal ultrasonographic studies, and laboratory investigations were reviewed. There were 78 stillborn autopsies during this 10-year period; the mean gestational age was 28 weeks. The causes of fetal hydrops were identified in 88.5%; no cases of immune hydrops were detected. Anemia was the predominant cause of HF (n  =  33; 42.2%): related to homozygous α-thalassemia (n  =  17; 21.8%), twin-twin transfusion syndrome (n  =  8; 10.2%), hemoglobin H (n  =  3; 3.8%), lung hemorrhage (n  =  1; 1.3%), adrenal hemorrhage (n  =  1; 1.3%), and 3 cases of unspecified etiology (3.8%). Other causes of high-output failure included mass lesions resulting in vascular shunting (n  =  2; 2.6%) and 1 case each (1.3% each) of maternal diabetes mellitus, intestinal lymphangiectasia, and Beckwith-Wiedemann syndrome. Causes resulting in low-output cardiac failure were congenital heart disease (n  =  16; 20.5%) and thoracic space-occupying lesions (n  =  7; 9%). The remaining causes included fetal infection (n  =  5; 6.4%), congenital abnormalities suggestive of a chromosomal or genetic basis (n  =  2; 2.6%), and 1 case (1.3%) of placental vascular thrombosis. Nine cases (11.5%) had no identifiable cause. Thus, the most common cause of HF in this series was homozygous α-thalassemia, reflecting the geographic location of this series.

Alpha-thalassaemia

Alpha-thalassaemia is inherited as an autosomal recessive disorder characterised by a microcytic hypochromic anaemia, and a clinical phenotype varying from almost asymptomatic to a lethal haemolytic anaemia.

It is probably the most common monogenic gene disorder in the world and is especially frequent in Mediterranean countries, South-East Asia, Africa, the Middle East and in the Indian subcontinent. During the last few decades the incidence of alpha thalassaemia in North-European countries and Northern America has increased because of demographic changes. Compound heterozygotes and some homozygotes have a moderate to severe form of alpha thalassaemia called HbH disease. Hb Bart's hydrops foetalis is a lethal form in which no alpha-globin is synthesized. Alpha thalassaemia most frequently results from deletion of one or both alpha genes from the chromosome and can be classified according to its genotype/phenotype correlation. The normal complement of four functional alpha-globin genes may be decreased by 1, 2, 3 or all 4 copies of the genes, explaining the clinical variation and increasing severity of the disease. All affected individuals have a variable degree of anaemia (low Hb), reduced mean corpuscular haemoglobin (MCH/pg), reduced mean corpuscular volume (MCV/fl) and a normal/slightly reduced level of HbA₂. Molecular analysis is usually required to confirm the haematological observations (especially in silent alpha-thalassaemia and alpha-thalassaemia trait). The predominant features in HbH disease are anaemia with variable amounts of HbH (0.8-40%). The type of mutation influences the clinical severity of HbH disease. The distinguishing features of the haemoglobin Bart's hydrops foetalis syndrome are the presence of Hb Bart's and the total absence of HbF. The mode of transmission of alpha thalassaemia is autosomal recessive. Genetic counselling is offered to couples at risk for HbH disease or haemoglobin Bart's Hydrops Foetalis Syndrome. Carriers of alpha⁺- or alpha⁰-thalassaemia alleles generally do not need treatment. HbH patients may require intermittent transfusion therapy especially during intercurrent illness. Most pregnancies in which the foetus is known to have the haemoglobin Bart's hydrops foetalis syndrome are terminated due to the increased risk of both maternal and foetal morbidity.

Alpha-thalassaemia and population health in Southeast Asia

Alpha-thalassaemia mutations are common. In Southeast Asia, they cause Hb H disease and Hb Barts hydrops fetalis. Fetuses with the devastating Hb Barts hydrops fetalis due to the complete lack of alpha-globin gene die in utero or shortly after birth, often during the second or third trimesters. Recent findings on patients with Hb H disease who have only one active alpha-globin gene suggest that it is not necessarily a benign disorder as previously thought. The disease burden of these syndromes and their public health importance have been largely neglected. We review the population carrier frequencies of alpha-thalassaemia, and summarize the clinical features, diagnostic approaches, counselling and management of these common genetic disorders. Several practical proposals are made that, if implemented, can begin to address the issues of collaboration and improvement for care of these common diseases in the region.

Mutations in the paralogous human alpha-globin genes yielding identical hemoglobin variants

The human alpha-globin genes are paralogues, sharing a high degree of DNA sequence similarity and producing an identical alpha-globin chain. Over half of the alpha-globin structural variants reported to date are only characterized at the amino acid level. It is likely that a fraction of these variants, with phenotypes differing from one observation to another, may be due to the same mutation but on a different alpha-globin gene. There have been very few previous examples of hemoglobin variants that can be found at both HBA1 and HBA2 genes. Here, we report the results of a systematic multicenter study in a large multiethnic population to identify such variants and to analyze their differences from a functional and evolutionary perspective. We identified 14 different Hb variants resulting from identical mutations on either one of the two human alpha-globin paralogue genes. We also showed that the average percentage of hemoglobin variants due to a HBA2 gene mutation (alpha2) is higher than the percentage of hemoglobin variants due to the same HBA1 gene mutation (alpha1) and that the alpha2/alpha1 ratio varied between variants. These alpha-globin chain variants have most likely occurred via recurrent mutations, gene conversion events, or both. Based on these data, we propose a nomenclature for hemoglobin variants that fall into this category.

Newborn screening for hemoglobinopathies in California

BACKGROUND

Newborn screening (NBS) for hemoglobinopathies facilitates early identification of affected individuals to ensure the prompt institution of comprehensive medical care for affected newborns in California. When linked to extensive follow-up and education, NBS has been shown to significantly reduce mortality in children with sickle cell disease. Due to changing immigration patterns from Asia and Latin America, the State of California has witnessed an increased prevalence of clinically significant hemoglobin (Hb) disorders, including those resulting from novel genotypes. In 1999, newborn screening for Hb H disorders was incorporated in the statewide hemoglobinopathy screening program.

PROCEDURE

Primary screening for hemoglobin variants was performed using high performance liquid chromatography. Confirmatory testing on hemoglobinopathy mutations was performed by electropheresis techniques and genotyping methods.

RESULTS

Of 530,000 newborn samples screened annually in California, 2,118 samples were referred to the Hemoglobin Reference Laboratory (HRL) for confirmatory testing between January 1, 1998 and June 30, 2006 (0.05%). Sickle cell disease was most frequently observed (1 in 6,600 births) followed by alpha-thalassemia (1 in 9,000 births) and beta-thalassemia disease (1 in 55,000 births). The confirmatory analysis modified the initial screening in 5% of cases and revealed 25 rare or new genotypes. Diverse ethnicities were associated with hemoglobin mutations including Southeast Asian, Black, Indian/Asian, Middle Eastern, and Hispanic.

CONCLUSIONS

The California hemoglobinopathy screening program provides accurate diagnosis of hemoglobinopathies. Increasing incidence of diverse mutations require new strategies of laboratory screening, counseling, and patient management.

Alpha thalassemia major--new mutations, intrauterine management, and outcomes

Alpha thalassemia disorders are a group of hereditary anemias caused by absent or decreased production of the alpha chain of hemoglobin. Hemoglobin Bart's hydrops fetalis is usually a fatal in-utero disease caused by absence of the alpha genes. However, the molecular and genotypic expression of hemoglobin Bart's varies and increasing numbers of births are being reported. Population screening and prenatal diagnosis of at-risk couples is essential but often not performed. Most affected pregnancies are often undetected, resulting in severe fetal and maternal complications. Noninvasive monitoring by Doppler ultrasonagraphy with intrauterine transfusion therapy has changed the prognosis for this disorder. These advances in intrauterine and postnatal therapy have resulted in ethical dilemmas for the family and the provider.

Comparison of red blood cell hematology among normal, alpha-thalassemia-1 trait, and hemoglobin Bart's fetuses at mid-pregnancy

The objective of this study was to compare red blood cell indices among normal, alpha-thalassemia-1 trait, and hemoglobin (Hb) Bart's fetuses at mid-pregnancy. A total of 87 pregnancies (88 fetuses) at risk of homozygous alpha-thalassemia-1, who underwent cordocentesis including the measurement of Hb level and red blood cell indices of fetuses at 18-22 weeks of gestation at Maharaj Nakorn Chiang Mai Hospital, were recruited into this study. The final outcome was based on the fetal DNA analysis using PCR technique for SEA type alpha-thalassemia-1. Fetuses were divided into three groups: normal, alpha-thalassemia-1 trait, and homozygous alpha-thalassemia-1 (Hb Bart's disease). The mean gestational age of the 87 pregnant women recruited into the study was 18.7 +/- 0.8 weeks. According to the DNA analysis, the incidence of Hb Bart's disease, alpha-thalassemia-1 trait, and normal fetuses were 29.5%, 45.5%, and 25%, respectively. The mean Hb level, mean corpuscular volume, mean corpuscular Hb, and mean cell Hb concentration were significantly different in all three groups of fetuses. Moreover, these differences were also found among fetuses with the alpha-thalassemia-1 trait and those that were normal. Ninety-two percent of fetuses with Hb Bart's disease had some degree of anemia at mid-pregnancy. However, two Hb Bart's fetuses did not have anemia. Furthermore, two fetuses in the alpha-thalassemia-1 trait group were mildly anemic, but most (95%) were not. There is a highly significant difference in red blood cell indices among normal, alpha-thalassemia-1 trait, and Hb Bart's fetuses, and most fetuses with Hb Bart's disease have some degree of anemia from mid-pregnancy.

Outcome of intensive care of homozygous alpha-thalassaemia without prior intra-uterine therapy

AIM

To review the outcome of homozygous alpha-thalassaemia without prior intra-uterine therapy treated in neonatal intensive care unit and identify the factors associated with survival.

METHODS

The hospital records of all patients with homozygous alpha-thalassaemia treated in our neonatal intensive care unit in the last 15 years were reviewed. A literature search beginning in the year 1980 was done to identify homozygous alpha-thalassaemia actively treated in neonatal intensive care units. Those receiving prior intra-uterine therapy were excluded. The following information was collected: the severity of hydrops, sizes of liver and spleen, haemoglobin level, Apgar score at 5 min, ventilator settings, timing and forms of red blood cell transfusion and presence of persistent hypoxaemia. The survivors and the non-survivors were compared.

RESULTS

In our centre, in the last 15 years there were six infants born with homozygous alpha-thalassaemia who did not receive intra-uterine therapy; one survived and five succumbed despite aggressive respiratory therapy. In our literature search there were more reports of survivors (10) than non-survivors (six) for these infants, suggesting a reporting bias towards selection of rare cases of survival. Apgar score of four or above occurred in seven of the eight survivors with data available in the reports, whereas this occurred in four of the 11 non-survivors (P = 0.035, Fisher Exact test). Five of the 11 survivors had abnormal neurological outcome including developmental delay and spastic quadriplegia.

CONCLUSION

Without prior intra-uterine therapy, homozygous alpha-thalassaemia has grave outlook in terms of mortality and morbidity despite aggressive respiratory therapy.

An improved method for the diagnostic approach of alpha+-thalassaemia

An improved method for the diagnostic approach of alpha(+)-thalassaemia is described. The method is based on five common parameters: absence of iron deficiency, mild morphological abnormalities of erythrocytes, normal or slightly reduced erythrocytic indices MCV and MCH, normal chromatographic findings, and presence of haemoglobin H inclusions in erythrocytes with methyl-violet stain after, but not before, incubation with oxidant agent. We studied by DNA analysis, 58 subjects fulfilling the above mentioned diagnostic criteria and we found that 50 of them (86.2%) had a alpha-globin gene defect. In the remaining eight subjects (13.8%) no alpha-gene defect could be documented with the techniques used in the DNA analysis, which detect the six well-known alpha(+)-thalassaemic defects in the Greek population. We conclude that the improved method, we described has a high sensitivity and accuracy in the screening of alpha(+)-thalassaemia.

Anemia and hydrops in a fetus with homozygous hemoglobin constant spring

Hemoglobin Constant Spring (Hb CS) is an unstable hemoglobin (Hb) variant that results from a nucleotide substitution at the termination codon of the alpha2-globin gene. The compound heterozygosity of alpha-thalassemia and Hb CS (--/alphaCSalpha) results in a Hb H/CS disease which is clinically more severe than deletional Hb H disease. Homozygosity of Hb CS (alphaCSalpha/alphaCSalpha) is generally characterized with mild hemolytic anemia, jaundice, and splenomegaly. The authors report 1 case with Hb CS homozygosity who presented with fetal anemia and hydrops. Intrauterine transfusions were given which rendered a favorable outcome. This report demonstrates an unusual and serious in utero complication in a fetus with Hb CS/CS.

Pilot programs in newborn screening

The term "pilot study" has been used over the years to describe the evaluation of the many elements involved in deciding whether a proposed condition should be added to a newborn screening (NBS) panel, and until recently, was unilaterally used to describe the evaluation of the assay to be used before the condition was officially adopted by a state for its newborn screening panel. Since Guthrie's introduction of screening for PKU, each time a new condition was added to the panel, the screening assay itself was validated through a population-based trial, in which the test was performed with de-identified samples to avoid association between the test result and the infant. This is considered by the laboratory as the "pilot phase" of adding a new condition. To advance the science of NBS, especially to accommodate new technologies that may provide new types of information (genetic versus physiological) for each new condition, pilot programs are essential. Involvement of the clinical community serves to improve these evaluations and provides the needed clinical validation of decisions made as a result of it. This paper describes the historical context of pilot programs in population-based NBS that utilize laboratory-based markers as indicators of concern; specifically, three applications that demonstrate different approaches to the use of pilots in adding conditions to a NBS panel are described.

α-Thalassemia: Hb H Disease and Hb Barts Hydrops Fetalis

alpha-Thalassemia mutations are one of the most common mutations of man, and they cause Hb H disease and Hb Barts hydrops fetalis. Hb H disease is not necessarily a benign disorder as has been generally thought. Furthermore, in southern China and in Southeast Asia, there are 2-3 times more fetuses afflicted with the invariably fatal Hb Barts hydrops fetalis than with the beta-thalassemia major or intermedia. These findings underscore the public health importance of these hereditary disorders, and they call for better education, diagnosis, treatment, prevention, and research for these diseases.

Changing Patterns of Thalassemia Worldwide

Thalassemia is a growing global public health problem with an estimated 900,000 births of clinically significant thalassemia disorders expected to occur in the next 20 years. This growth will occur in disorders previously uncommon in many parts of the world. In particular, hemoglobin (Hb) E-beta-thalassemia and Hb H disease account for much of the projected increases in thalassemia. Worldwide, Hb E-beta-thalassemia is one of the most frequent hemoglobinopathies. The incidence of Hb E approaches 60% of the populations in many regions of Southeast Asia. In coastal regions of North America, its prevalence is rapidly growing. The severity of Hb E-beta-thalassemia ranges from a complete lack of symptoms to transfusion dependence. alpha-Thalassemia diseases, often considered benign, are now recognized to be more severe than originally reported. Hb H, Hb H-Constant Spring (CS), and homozygous alpha-thalassemia affect at least a million people worldwide. California considers Hb H disease a public health problem and has initiated a neonatal screening program for Hb H and particularly Hb H-CS. Homozygous alpha-thalassemia, usually fatal, is also being more commonly detected. Several regions have initiated universal prenatal screening programs to address homozygous alpha-thalassemia. In summary, the prognosis for thalassemia disorders is improving, but prenatal diagnosis and neonatal screenings are needed. Comprehensive services that address language and social barriers as well as access to Hb F-enhancing agents and transfusions are needed.

Hemoglobin H hydrops fetalis syndrome resulting from the association of the - -SEA deletion and the alphaQuong Szealpha mutation in a Chinese woman

A case with Hb H hydrops fetalis syndrome resulting from the association of the - -(SEA) deletion and the alpha(Quong Sze)alpha mutation is reported. This is the first description of Hb H hydrops associated with the Hb Quong Sze mutation.

Hemoglobin Titusville, a low oxygen affinity variant hemoglobin, in a family of Northern European background

We report the second case of Hb Titusville in a family of Northern European background. This variant hemoglobin caused by an alpha-globin gene mutation has decreased oxygen affinity. Correct diagnosis is clinically important to spare affected individuals extensive investigations into other causes of low oxygen saturation in peripheral blood.

Hydrops fetalis associated with homozygosity for hemoglobin Taybe (alpha 38/39 THR deletion) in newborn triplets

Hemoglobin Taybe is an unstable alpha-chain hemoglobin variant caused by a deletion of a threonine residue at codon 38 or 39 of the alpha-1 globin chain. We describe preterm infant triplets born with hydrops fetalis and anemia who were found by DNA analysis to be homozygous for hemoglobin Taybe. All three infants developed intrauterine hemolytic anemia, which subsequently led to hydrops fetalis. To the best of our knowledge, this is the first description of hydrops fetalis associated with this hemoglobinopathy. We suggest that hemoglobin Taybe be considered in the differential diagnosis of hydrops fetalis and that known affected fetuses be carefully followed both antenatally and postnatally.

Co-inheritance of Hb Pak Num Po, a novel alpha1 gene mutation, and alpha0 thalassemia associated with transfusion-dependent Hb H disease

Hb H disease is generally associated with moderate to severe anemia but rarely requires regular blood transfusion. We recently studied two apparently unrelated patients with transfusion-dependent Hb H disease. Hemoglobin studies demonstrated Hb H and Hb Bart's without other detectable abnormal globin species. Extensive molecular analyses of the alpha globin genes and their regulatory sequence (HS-40) revealed that both patients are compound heterozygotes for alpha0 thalassemia (--(SEA)) and a novel point mutation, a thymidine insertion after codon 131 of the alpha1 gene. The resulting frameshift gives rise to a highly unstable alpha globin chain, which we refer to as "Hb Pak Num Po," containing an additional 34 amino acids. This unusual alpha1 globin variant clearly causes alpha thalassemia, but the unexpectedly severe phenotype suggests that this mutation may have additional effects on red cell physiology. A PCR-based (ARMS) assay was developed for rapid detection of this novel mutation, and this might be useful to study the prevalence of this novel mutation which poses potentially significant clinical consequences in populations of Southeast Asia. Detecting carriers of this mutation using the molecular diagnostic procedures described will provide the means to screen and prevent a potentially severe form of alpha thalassemia in Thailand.