The Clinical Phenotypes of Alpha Thalassemia

A sample-in- result -out microfluidic system for β-thalassemia diagnostics via direct whole blood PCR-reverse dot blot

OBJECTIVE

Existing thalassemia detection methods demand high - end labs and have complex procedures, leading to long testing cycles. This study aims to develop a convenient detection method integrated with a microfluidic platform for a sample - to - result process.

METHOD

First, optimal conditions for the whole blood direct PCR - reverse dot hybridization (dPCR - RDB) system were explored. Then, its performance was evaluated with clinical samples. Finally, the entire process was integrated into a palm - sized microfluidic chip for "sample - in, result - out" detection.

RESULT

A stable dPCR - RDB system was established. Clinical verification on 149 samples showed a 0.1 μl whole - blood minimum detection limit, 100 % specificity, and resistance to high triglyceride and bilirubin levels. It had 100 % positive and negative coincidence rates with traditional methods (kappa = 1). The microfluidic - integrated platform achieved "sample - in, result - out" with 0.5-1 μl blood in 130 min, sans a PCR lab.

CONCLUSION

A "sample - in, result - out" microfluidic gene detection platform using whole blood as the template was successfully established.

Risk factors for hemorrhagic cystitis in children with severe beta-thalassemia after allogeneic hematopoietic stem cell transplantation

Purpose

To investigate the risk factors for hemorrhagic cystitis (HC) in children with severe beta-thalassemia after allogeneic hematopoietic stem cell transplantation (allo-HSCT).

Methods

The clinical data of 152 children under the age of 15 who underwent allo-HSCT between January 2011 and December 2021 were retrospectively analyzed. The incidence of HC and related variables were evaluated using univariate analysis. Variables with statistical significance (P < 0.05) were included in a multivariable logistic regression model to identify independent risk factors for HC.

Results

Among the 152 children, 42 developed HC, with an incidence rate of 27.63%. The median onset time of HC was 25 days (IQR: 10-38.75 days). Univariate analysis indicated that older transplantation age, elevated pre-transplant serum ferritin levels, cytomegalovirus (CMV) infection, and prolonged neutrophil engraftment time were associated with HC occurrence (P < 0.05). Multivariable logistic regression further confirmed that older transplantation age (OR 1.236, 95% CI: 1.031-1.531, P = 0.033), elevated pre-transplant ferritin levels (OR 1.053, 95% CI: 1.028-1.086, P < 0.01), CMV infection (OR 11.522, 95% CI: 2.912-76.345, P = 0.002), and prolonged neutrophil engraftment time (OR 1.385, 95% CI: 1.109-1.793, P < 0.01) were independent risk factors for HC.

Conclusion

Older transplantation age (>5.95 age years old), elevated pre-transplant serum ferritin levels, CMV infection, and delayed neutrophil engraftment are independent risk factors for HC in children with severe beta-thalassemia after allo-HSCT. Early identification and intervention for these risk factors are crucial in reducing the incidence of HC.

Impact of HbE mutation on the clinical severity of HbH disease: A multicentre study from Thailand

Haemoglobin (Hb) H disease and HbH disease with co-inherited HbE mutation are the most prevalent forms of α-thalassaemia in Southeast Asia. Data were limited when comparing clinical phenotypes between these two patient groups. We conducted a Thai multicentre study and enrolled 588 patients [median (IQR) age 13.0 (6.7-20.3) years], including those with deletional HbH disease with (n = 47) and without (n = 187) co-inherited HbE mutation and non-deletional HbH disease with (n = 101) and without (n = 253) co-inherited HbE mutation. Patients with HbH disease with co-inherited HbE mutation suffered more severe manifestations than those without. This observation was more pronounced in patients with non-deletional HbH disease. A greater proportion of patients with non-deletional HbH disease with co-inherited HbE mutation (43.6%) eventually required regular transfusions compared to those without (30.4%, p = 0.019). Among those with non-deletional HbH disease who did not require regular transfusions, Hb levels were lower in patients with co-inherited HbE mutation [8.1 (7.2-8.6) vs. 8.8 (8.2-9.5) g/dL, p < 0.001]. Among patients requiring regular transfusions who underwent splenectomy, 11/12 patients with non-deletional HbH disease stopped transfusion compared with 1/3 in non-deletional HbH disease with co-inherited HbE mutation group (p = 0.024). These findings provide insights for the clinical monitoring and management of HbH disease in the region.

Microcytosis Merits Evaluation: A Case Report of Hemoglobin S With Hereditary Persistence of Fetal Hemoglobin (HbS-HPFH Syndrome)

Microcytosis is commonly encountered in primary care. Among patients with normal iron stores or compatible family history, hemoglobin electrophoresis, traditionally performed with gel electrophoresis and now through combination capillary electrophoresis/high-performance liquid chromatography, can diagnose thalassemic disorders or, rarely, a hemoglobinopathy. We present a case of an incidentally discovered microcytosis in a 34-year-old male patient where the workup led to a diagnosis of Hemoglobin S with Hereditary Persistence of Fetal Hemoglobin (HbS-HPFH syndrome). The diagnosis led providers to re-evaluate the patient's chronic hip pain, upon which the patient was found to have bilateral osteonecrosis of the femurs. Microcytosis is a lab abnormality that is often asymptomatic and, therefore, may be ignored or overlooked. When encountering microcytosis in primary care, it is important to identify the etiology using a brief, targeted approach. This may directly impact management and can prove helpful when considering future complaints of the patient.

Diagnosis and Treatment of Alpha Thalassemia Major

Alpha thalassemia major (ATM) is the most severe form of α-thalassemia, with thousands of cases annually throughout the world. It was historically incompatible with life, with almost all affected individuals dying at or before birth. Recent advances utilizing early, serial intrauterine transfusions have resulted in improved outcomes, including improved neurocognitive functioning and less congenital anomalies. At-risk families should be identified pre-conceptually for counseling and options such as preimplantation genetic testing. ATM, when diagnosed prenatally, requires counseling about termination options and transfusion therapy. Postnatally, aggressive transfusion, in contrast to standard thalassemia transfusion protocols, suppresses ineffective erythropoiesis and hemoglobin Barts formation. These advances have changed the course of ATM in utero and postnatally. Preliminary results suggest iron chelation may be safely administered after one year of age with monitoring, including quantitative liver iron measurements. Patients with ATM can now survive on chronic transfusion therapy and potentially be cured by hematopoietic cell transplantation (HCT). New therapies continue to emerge, including in-utero stem cell transplantation using maternal stem cells and Phase 1 gene therapy trials evaluating reactivation of the embryonic α-globin (zeta) gene and encoding the α-globin gene. Globally, an international working group has been formed to address ATM, which should lead to advances worldwide.

Disease burden, management strategies, and unmet needs in α-thalassemia due to hemoglobin H disease

Alpha-thalassemia is an inherited blood disorder caused by impaired α-globin chain production, leading to anemia and other complications. Hemoglobin H (HbH) disease is caused by a combination of mutations generally affecting the expression of three of four α-globin alleles; disease severity is highly heterogeneous, largely driven by genotype. Notably, non-deletional mutations cause a greater degree of ineffective erythropoiesis and hemolysis, higher transfusion burden, and increased complication risks versus deletional mutations. There are limited treatment options for HbH disease, and effective therapies are needed. This review discusses the pathophysiology of HbH disease, current management strategies, unmet needs, and emerging treatment options.

Hemoglobinopathies in the Neonate

Hemoglobinopathies in neonates constitute a group of disorders influenced by genetic mutations in the human globin genes. They are often broadly categorized into quantitative defects or qualitative defects, though they are not mutually exclusive. In quantitative defects, the mutation causes insufficient production of a normal globin chain, which can range from no production to mild deficiency. These are typically referred to as thalassemias. In qualitative defects, the structure of the hemoglobin is altered. The most common structural hemoglobinopathy is sickle cell disease. During fetal development, distinct globin chains are synthesized, which undergo a progressive switch to adult globin chains perinatally. This affects the timing of the clinical presentation of these disorders and thus, our ability to diagnose them. In this review, we focus on the epidemiology, genetic causes, clinical presentation, and general overview and management of common hemoglobin disorders that may be encountered in the neonatal period.

Phenotypic Analysis of the HBA2: C.95 G > A Mutation in China

This study aimed to analyze the clinical phenotype of the HBA2: c.95G>A mutation in the Chinese population and to provide guidance for clinical diagnosis and genetic counseling. Peripheral blood samples were collected from 16 patients, including 6 newborns, 2 children, and 8 adults. Hematological parameters and hemoglobin electrophoresis were analyzed, and genotypes were identified using methods such as PCR combined with reverse dot blot (RDB), nested PCR, gap polymerase chain reaction (Gap-PCR), and DNA sequencing. The results showed that 10 patients had mild anemia, 2 had moderate anemia, and 12 exhibited microcytic hypochromic features with MCV values ranging from 53 to 74.7 fl and MCH values from 16.2 to 25.4 pg. Additionally, 3 cases displayed obvious HbH + HbBarts bands (>15%). Among the 16 cases, various combinations of the HBA2: c.95G>A mutation were observed: one case had -α3.7 combined with HBA2: c.95G>A, another had -α4.2 combined with HBA2: c.95G>A, and five had -SEA combined with HBA2: c.95G>A, while the remaining cases were HBA2: c.95G>A heterozygotes. The study concludes that the HBA2: c.95G>A mutation in the α2 globin gene causes α+ thalassemia. When this mutation is combined with the Southeast Asian deletion (-SEA), it results in HbH disease, characterized by moderate microcytic hypochromic anemia and the presence of HbH + HbBarts bands.

Routine antenatal molecular testing for α-thalassemia at a tertiary referral hospital in China: ten years of experience

Objective

This study aimed to evaluate the efficacy of α-thalassemia gene testing as a part of an antenatal intervention program over a 10-year period.

Methods

All patients underwent α-thalassemia gene testing, which included the analysis of three types of deletions and mutations. Rare α-thalassemia gene testing was performed using Sanger sequencing, multiplex ligation-dependent probe amplification, and sequencing techniques. Prenatal diagnosis was performed in high-risk couples using chorionic villus sampling or amniocentesis.

Results

From 2010 to 2019, among the 91,852 patients examined, α-thalassemia mutations were identified in 41.78% of patients. The most frequent α0 gene mutation was--SEA, followed by--THAI. Two rare α0-thalassemia gene mutations at --32.8 and --230, were also observed. A total of 2,235 high-risk couples were identified, of which 562 were affected, including three with the--SEA/--THAI genotype and one with the--SEA/--230 genotype. Additionally, prenatal diagnosis revealed four cases of fetal anemia and/or mild edema, along with two cases of severe fetal edema. Chromosome and gene chip results were normal. Thalassemia gene testing showed an αCSα/αCSα genotype in four patients with anemia and/or mild edema, while two patients with severe fetal edema had one--SEA/αCSα genotype and one--SEA/--GX genotype. Using the cut-off points of 74.6 fL and 24.4 pg as criteria for identifying α0-thalassemia carriers and HbH disease, the detection rate of missed diagnoses in high-risk couples is consistent with national guidelines for standards, potentially saving 10,217,700 ¥.

Conclusion

Routine molecular testing for α-thalassemia in high-risk prenatal populations effectively prevented severe α-thalassemia births. Despite the high cost, the cutoff points proposed by this study suggest that implementing screening using a new parameter has the potential to reduce current expenses.

The effect of red blood cell disorders on male fertility and reproductive health

Male infertility is defined as a failure to conceive after 12 months of unprotected intercourse owing to suspected male reproductive factors. Non-malignant red blood cell disorders are systemic conditions that have been associated with male infertility with varying severity and strength of evidence. Hereditary haemoglobinopathies and bone marrow failure syndromes have been associated with hypothalamic-pituitary-gonadal axis dysfunction, hypogonadism, and abnormal sperm parameters. Bone marrow transplantation is a potential cure for these conditions, but exposes patients to potentially gonadotoxic chemotherapy and/or radiation that could further impair fertility. Iron imbalance might also reduce male fertility. Thus, disorders of hereditary iron overload can cause iron deposition in tissues that might result in hypogonadism and impaired spermatogenesis, whereas severe iron deficiency can propagate anaemias that decrease gonadotropin release and sperm counts. Reproductive urologists should be included in the comprehensive care of patients with red blood cell disorders, especially when gonadotoxic treatments are being considered, to ensure fertility concerns are appropriately evaluated and managed.

Genetic epidemiology of thalassemia in couples of childbearing age: over 6 years of a thalassemia intervention project

BACKGROUND

Shenzhen is one of the most populated metropolises in southern China where thalassemia is highly prevalent. The prevention of thalassemia inheritance is an ambition of child-bearing couples.

METHODS AND RESULTS

A total of 22,098 peripheral blood samples were collected from 11,049 potentially at-risk couples of childbearing age from Shenzhen. Thalassemia mutations were determined by PCR-based flow-through hybridization. The results identified 45.02% of the participants (9948 out of 22,098) as harboring globin gene mutations, distributed into 18 α-thalassemia alleles detected in 71.48% (7111 out of 9948) and 15 β-thalassemia alleles detected in 32.68% (3252 out of 9948) of all mutant individuals, among which 415 individuals carried both α- and β-thalassemia alleles. The most frequent phenotypes for α-globin variations were --SEA/αα (63.37%), -α3.7/αα (18.66%), and -α4.2/αα (7.31%), and those for β-globin variations were β41-42/βN (34.96%), β654/βN (28.11%), and β17/βN (13.84%). A total of 970 high-risk couples who could possibly give birth to offspring with thalassemia intermedia or major were identified. In addition, the hematological indices were compared among thalassemia genotypes. Significant differences in MCH, MCV, Hb A, and Hb A2 levels among α-thalassemia minor (α+), trait (α0), and intermediate phenotypes (P < 0.05) and between βE/βN and the other β-thalassemia phenotypes (P < 0.05) were found. Moreover, GAP-PCR and next-generation sequencing further identified 42 rare mutations, 13 of which were first reported in the Chinese population. A novel mutation in the β-globin gene (HBB: c.246 C > A (rs145669504)) was also discovered.

CONCLUSIONS

This study presented a comprehensive analysis of thalassemia variations in a population from Shenzhen and may offer valuable insights for thalassemia control and intervention strategies in this area.

The Spectrum of α-Thalassemia Mutations in Syrian Patients

α-Thalassemia (α-thal) is a globally prevalent genetic disorder of hemoglobin (Hb) structure where the rate of α-globin chain synthesis is reduced or absent due to the presence of α-globin mutation(s). The aim of this study is to define the spectrum of α-globin gene mutations and evaluate their allele frequency in a group of α-thal carriers. A total of 55 individuals with possible α-thal patients were referred from the thalassemia centers in Syria. They have unexplained hypochromia and microcytosis. All patients were genetically tested for 21 common α-globin gene mutations using reverse hybridization kit. Seven different α-globin gene mutations and 13 different genotypes were detected in 55 patients. The two most frequently encountered mutations were -α3.7 deletion (47.1%) and --MED mutation (21.4%). The most commonly observed genotype was -α3.7/αα (40%), followed by --MED/αα genotype (21.8%). We determined the most common α thalassemia mutations in the Syrian patients. α-Thalassemia mutations with deletions were mostly observed in our study.