Hb H Hydrops Fetalis Syndrome Caused by Association of the − −SEADeletion and Hb Constant Spring (HBA2: c.427T > C) Mutation in a Chinese Family

Erythropoiesis and Gene Expression Analysis in Erythroid Progenitor Cells Derived from Patients with Hemoglobin H/Constant Spring Disease

Hemoglobin H/Constant Spring (Hb H/CS) disease represents a form of non-deletional Hb H disease characterized by chronic hemolytic anemia that ranges from moderate to severe and may lead to transfusion-dependent thalassemia. To study the underlying mechanisms of this disease, we conducted an analysis of erythropoiesis and gene expression in erythroid progenitor cells derived from CD34+ hematopoietic stem/progenitor cells from patients with Hb H/CS disease and normal controls. Twelve patients with Hb H/CS disease and five normal controls were enrolled. Peripheral blood samples were collected to isolate CD34+ hematopoietic stem/progenitor cells for the analysis of cell proliferation and differentiation. Six samples from patients with Hb H/CS disease and three controls were subsequently studied for gene expression by next generation sequencing analysis. Erythroid progenitor cells derived from patients with Hb H/CS disease exhibited a trend towards increased rates of erythroid proliferation and decreased cell viability compared to those from controls. Moreover, erythroid progenitor cells derived from patients with Hb H/CS disease demonstrated delayed terminal differentiation. Gene expression profiling revealed elevated levels of genes encoding molecular chaperones, including the heat shock protein genes (HSPs) and the chaperonin containing TCP-1 subunit genes (CCTs) in the Hb H/CS disease group. In summary, erythroid progenitor cells derived from patients with Hb H/CS disease exhibit a trend towards heightened erythroid proliferation, diminished cell viability, and delayed terminal differentiation. Additionally, the increased expression of genes encoding molecular chaperones was observed, providing information on potential underlying pathophysiological mechanisms.

Effective screening of hemoglobin Constant Spring and hemoglobin Paksé with several forms of α- and β-thalassemia in an area with a high prevalence and heterogeneity of thalassemia using capillary electrophoresis

Background and aims

We aimed to evaluate the efficiency of identification and quantification of hemoglobin (Hb) Constant Spring (CS) and Hb Paksé by capillary electrophoresis (CE).

Materials and methods

Blood samples collected from 2057 patients were used for identifying and quantifying Hb by CE. Molecular analysis of α- and β-thalassemia, Hb CS, and Hb Paksé was performed.

Results

Hb CS and Hb Paksé were identified in 573 samples (27.86%) with diverse genotypes. Thirty-eight samples (6.6%) showed no Hb CS peak. The sensitivity, specificity, positive predictive value, negative predictive value, and accuracy of Hb CS by CE were 93.37, 95.96, 89.92, 97.40, and 95.24%, respectively. The amount of Hb CS in those carrying Hb CS was 0.2-6.5% which showed an increasing trend according to the number of defective α-globin genes, in contrast to Hb A2 levels, which decreased. Hb CS level ≥1.0% accurately excluded heterozygotes and that of ≥2.0% could identify homozygotes.

Conclusion

CE has the high potential for identifying and quantifying Hb CS and Hb Paksé, especially in an area with a high prevalence of thalassemia. Hb CS levels can be used as a potential marker to distinguish the genotype of individuals carrying Hb CS.

Fetal Hemoglobin H Hydrops Fetalis: Another Three Case Reports

We report three cases of fetalis hydrops associated with nondeletional α-thalassemia. Two cases were caused by hemoglobin (Hb) H-Quong Sz disease, and one caused by homozygous Hb Constant Spring. Fetal hydrops occurred in the late second trimester in all three cases. Our study indicates that for pregnancies at risk for fetal nondeletional Hb H disease, strict ultrasound follow-up is particularly important. Even without techniques of intrauterine transfusion treatment, early prenatal diagnosis can enable parents to make timely decisions.

Severity scoring system to guide transfusion management in pediatric non-deletional HbH

BACKGROUND

Hemoglobin (Hb) H is generally recognized as mild thalassemia, despite its actual phenotypic diversity. A disease severity scoring system to guide initiation of regular transfusion among severely affected pediatric patients has not previously been reported.

METHODS

Patients with HbH were classified into transfusion-dependent thalassemia (TDT) and non-transfusion-dependent thalassemia (NTDT) as a surrogate for disease severity. Alpha-globin genotypes and relevant clinical parameters associated with TDT were identified. Univariate and multiple logistic regression analyses were performed to yield the most suitable severity scoring system.

RESULTS

From 246 patients with a median age of 14.3 (interquartile range 9.9-18.4) years initially enrolled into the study, the chance of having severe disease and developing TDT was remarkable only among patients with non-deletional HbH, for whom the scoring system was developed. Univariate and multiple logistic regression analyses resulted in three retained parameters associated with TDT, β-coefficients of which were used to develop the score. The final scoring system comprised age at diagnosis <2 years (score = 1), spleen size ≥3 cm (score = 1) and Hb at steady-state <7 (score = 4) or 7-8 g/dL (score = 3). A cutoff score ≥4 was associated with severe disease likely requiring regular transfusion (sensitivity 89.3%, specificity 81.4%), given regular transfusion resulted in maintained growth. The scoring system was validated in the second cohort of 77 non-deletional HbH, from which comparable sensitivity and specificity were obtained.

CONCLUSION

The newly developed scoring system was practical and helpful to highlight severely affected pediatric non-deletional HbH patients with potential needs of regular transfusion. This can be used as a guide for optimal treatment and disease monitoring in the future.

Direct PCR assays without DNA extraction for rapid detection of hemoglobin Constant Spring and Pakse' genes: application for carrier screening and prenatal diagnosis

Hemoglobin Constant Spring (Hb CS) and Hb Pakse' (PS) are the common non-deletional α⁺-thalassemia found in Thailand. These two variants can cause severe thalassemia syndromes, especially in fetus and neonate. Molecular diagnosis is the only confirmatory method because Hb CS and Hb PS are usually missed by routine screening and Hb analysis. Therefore, we aimed to develop rapid direct PCR for the diagnosis of Hb CS and PS genes. Multiplex direct PCR assays for identifying the Hb CS and PS genes in whole blood (WB) and amniotic fluid (AF) specimens were developed. The assays were firstly validated on 290 unrelated whole blood specimens. Hb CS and PS carriers were identified in 67 (23.1%) and 6 (2.1%) cases, respectively. A 100% concordant result as compared to routine PCR assay was observed. The direct PCR assays have been applied successfully for prenatal diagnosis in two families. The result showed that the fetuses were affected by homozygous Hb CS and compound heterozygous Hb CS/Hb PS. Accurate prenatal diagnosis of these families was observed using the newly developed assays. These assays should be applicable in routine thalassemia diagnostics as well as in the large-scale screening of Hb CS and PS in the region.

Hematological Characteristics of Hb Constant Spring (HBA2: c.427T>C) Carriers in Mainland China

Hb Constant Spring (Hb CS) (HBA2: c.427T>C) is a common α-globin variant causing α-thalassemia (α-thal) phenotypes in mainland China. In this study, we evaluated the efficiency of erythrocyte parameters and capillary electrophoresis (CE) in the determination of Hb CS in blood samples from Hb CS carriers. Based on molecular diagnosis, there were 462 patients carrying Hb CS: 411 Hb CS heterozygotes, seven carried Hb H-Hb CS disease, 18 compound heterozygotes for Hb CS/α⁺-thal, and 26 double heterozygotes for Hb CS and β-thalassemia (β-thal). Forty-three cases had no Hb CS peak visible on CE, including all 26 cases of double heterozygotes for Hb CS and β-thal, and 17 cases of heterozygotes carrying only Hb CS. Hb CS heterozygotes, those without a Hb CS peak, presented with lower hemoglobin (Hb), mean corpuscular volume (MCV) and mean corpuscular Hb (MCH) values than those with a Hb CS peak. The MCV <80.0 fL yielded a detection rate of 87.8% for screening individuals carrying Hb CS. Therefore, we emphasize that if one partner of a couple has tested positive for α⁰-thal, the other should be subjected to detailed screening for this nondeletional allele using molecular analysis, regardless of his/her red cell indices and electrophoretic chromatogram.

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.

A Rare Hb H Hydrops Fetalis Syndrome Caused by the - -SEA Deletion in Combination with the Rare Hb Hirosaki Mutation in a Chinese Patient

Despite the milder clinical severity of Hb H patients compared with those of Hb Bart's hydrops fetalis or patients with β-thalassemia major (β-TM), a few cases of Hb H hydrops fetalis syndrome have been reported so far. Here, we describe, for the first time in the Chinese population, one case of a neonate with Hb H hydrops fetalis syndrome caused by the - -^SEA (Southeast Asian) deletion in combination with the Hb Hirosaki (HBA2: c.132C>G, p.Phe43Leu) mutation. Our study highlights the importance of continuous fetal monitoring using ultrasonography and blood screening studies of fetuses. Appropriate genetic counseling and comprehensive clinical follow-up should be performed on a pregnant woman who carried an α⁰-thalassemia (α⁰-thal) deletion and had a Hb H or Hb Bart's hydrops fetalis offspring, especially if the woman's partner also carried a hemoglobinopathy.

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.