Homozygous α-thalassemia: Challenges surrounding early identification, treatment, and cure

Hemoglobin Bart's hydrops fetalis: charting the past and envisioning the future

ABSTRACT

Hemoglobin Bart's hydrops fetalis syndrome (BHFS) represents the most severe form of α-thalassemia, arising from deletion of the duplicated α-globin genes from both alleles. The absence of α-globin leads to the formation of nonfunctional hemoglobin (Hb) Bart's (γ4) or HbH (β4) resulting in severe anemia, tissue hypoxia, and, in some cases, variable congenital or neurocognitive abnormalities. BHFS is the most common cause of hydrops fetalis in Southeast Asia; however, owing to global migration, the burden of this condition is increasing worldwide. With the availability of intensive perinatal care and intrauterine transfusions, an increasing number of patients survive with this condition. The current approach to long-term management of survivors involves regular blood transfusions and iron chelation, a task made challenging by the need for intensified transfusions to suppress the production of nonfunctional HbH-containing erythrocytes. Although our knowledge of outcomes of this condition is evolving, it seems, in comparison to individuals with transfusion-dependent β-thalassemia, those with BHFS may face an elevated risk of complications arising from chronic anemia and hypoxia, ongoing hemolysis, iron overload, and from their respective treatments. Although stem cell transplantation remains a viable option for a select few, it is not without potential side effects. Looking ahead, potential advancements in the form of genetic engineering and innovative therapeutic approaches, such as the reactivation of embryonic α-like globin gene expression, hold promise for furthering the treatment of this condition. Prevention remains a crucial aspect of care, particularly in areas with high prevalence or limited resources.

Αlpha-thalassemia: A practical overview

α-Thalassemia is an inherited blood disorder characterized by decreased synthesis of α-globin chains that results in an imbalance of α and β globin and thus varying degrees of ineffective erythropoiesis, decreased red blood cell (RBC) survival, chronic hemolytic anemia, and subsequent comorbidities. Clinical presentation varies depending on the genotype, ranging from a silent or mild carrier state to severe, transfusion-dependent or lethal disease. Management of patients with α-thalassemia is primarily supportive, addressing either symptoms (eg, RBC transfusions for anemia), complications of the disease, or its transfusion-dependence (eg, chelation therapy for iron overload). Several novel therapies are also in development, including curative gene manipulation techniques and disease modifying agents that target ineffective erythropoiesis and chronic hemolytic anemia. This review of α-thalassemia and its various manifestations provides practical information for clinicians who practice beyond those regions where it is found with high frequency.

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.

The impact of in utero transfusions on perinatal outcomes in patients with alpha thalassemia major: the UCSF registry

Alpha thalassemia major (ATM) is a hemoglobinopathy that usually results in perinatal demise if in utero transfusions (IUTs) are not performed. We established an international registry (NCT04872179) to evaluate the impact of IUTs on survival to discharge (primary outcome) as well as perinatal and neurodevelopmental secondary outcomes. Forty-nine patients were diagnosed prenatally, 11 were diagnosed postnatally, and all 11 spontaneous survivor genotypes had preserved embryonic zeta-globin levels. We compared 3 groups of patients; group 1, prenatally diagnosed and alive at hospital discharge (n = 14), group 2, prenatally diagnosed and deceased perinatally (n = 5), and group 3, postnatally diagnosed and alive at hospital discharge (n = 11). Group 1 had better outcomes than groups 2 and 3 in terms of the resolution of hydrops, delivery closer to term, shorter hospitalizations, and more frequent average or greater neurodevelopmental outcomes. Earlier IUT initiation was correlated with higher neurodevelopmental (Vineland-3) scores (r = -0.72, P = .02). Preterm delivery after IUT was seen in 3/16 (19%) patients who continued their pregnancy. When we combined our data with those from 2 published series, patients who received ≥2 IUTs had better outcomes than those with 0 to 1 IUT, including resolution of hydrops, delivery at ≥34 weeks gestation, and 5-minute appearance, pulse, grimace, activity, and respiration scores ≥7. Neurodevelopmental assessments were normal in 17/18 of the ≥2 IUT vs 5/13 of the 0 to 1 IUT group (OR 2.74; P = .01). Thus, fetal transfusions enable the survival of patients with ATM and normal neurodevelopment, even in those patients presenting with hydrops. Nondirective prenatal counseling for expectant parents should include the option of IUTs.

Advances in the management of α-thalassemia major: reasons to be optimistic

α-Thalassemia major (ATM) is a severe disease resulting from deletions in all 4 copies of the α-globin gene. Although it is usually fatal before birth, the advent of in utero transfusions has enabled survival of a growing number of children. Postnatal therapy consists of chronic transfusions or stem cell transplantation, similar to patients with β-thalassemia major. In this review, we discuss the experience with postnatal stem cell transplantation in patients with ATM, as well as the ongoing phase 1 clinical trial of in utero stem cell transplantation for this condition.

Microbiome-gut-brain axis in cancer treatment-related psychoneurological toxicities and symptoms: a systematic review

PURPOSE

The microbiome-gut-brain (MGB) axis provides a dynamic model to understand associations between the gut microbiota and psychoneurological comorbidities. The role of the MGB axis in cancer treatment-related psychoneurological symptoms (PNS) remains unknown. The purpose of this study was to conduct a systematic review of the existing literature to identify the influence of the gut microbiota on cancer and cancer treatment-related PNS and toxicities mediated by the MGB axis.

METHODS

We searched the databases of PubMed, Embase, and Web of Science from their earliest records to October 2019. All studies identified in the database searches were screened by title and abstract, followed by a review of the full texts. The Johns Hopkins Nursing Evidence-Based Practice Model was adopted to assess the evidence levels and qualities; the Joanna Briggs Institute critical appraisal tools were used to assess the methodological quality and the possibility of bias for each included study. All the study findings were combined, synthesized, and presented through narrative format.

RESULTS

Six studies were included in this systematic review. These studies primarily focused on cancer survivorship while receiving chemotherapy, and they were conducted between 2016 and 2019. The gut microbiome was assessed via fecal samples, which were analyzed using 16S rRNA sequencing approaches. With small-scale studies, the gut microbiota was associated with cancer treatment-related PNS, including fatigue, anxiety, depression, sleep disturbance, cognitive impairment, and chemotherapy-induced peripheral neuropathy. A higher relative abundance of Bacteroides was associated with a higher level of fear of cancer recurrence but a higher relative abundance of Lachnospiraceae.g and Ruminococcus was associated with a lower level in fear of cancer recurrence. Changes in fatigue interference were associated with the frequency of genera Faecalibacterium and Prevotella, and changes in anxiety were associated with the frequency of genera Coprococcus and Bacteroides.

CONCLUSIONS

The gut microbiota showed significant associations with cancer treatment-related PNS. Recent work regarding the MGB axis in cancer psychoneurological toxicities focused primarily on individual toxicity and symptoms in cancer survivors with chemotherapy exposure. Associations between the gut microbiota and PNS should be further studied in cancer populations across different ages, cancer types, and treatment modalities.

An international registry of survivors with Hb Bart's hydrops fetalis syndrome

Hemoglobin (Hb) Bart's hydrops fetalis syndrome (BHFS) resulting from α0-thalassemia is considered a universally fatal disorder. However, over the last 3 decades, improvements in intrauterine interventions and perinatal intensive care have resulted in increasing numbers of BHFS survivors. We have initiated an international registry containing information on 69 patients, of which 31 are previously unpublished. In this perspective, we analyze the available clinical information to document the natural history of BHFS. In the future, once we have accrued sufficient cases, we aim to build on this study and provide information to allow counseling of at-risk couples. To date, 39 patients have survived beyond the age of 5 years, 18 of whom are now older than 10 years. Based on the available cases, we find evidence to suggest that intrauterine therapy provides benefits during the perinatal and neonatal period; however, it may not provide additional benefits to long-term growth and neurodevelopmental outcomes. Growth retardation is a major adverse long-term outcome among BHFS patients with ∼40% being severely affected in terms of weight and ∼50% in terms of height. There is also an increased risk of neurodevelopmental delay as we find 20% (11/55) of BHFS survivors suffer from a serious delay of ≥6 months. Most patients in the registry require lifelong transfusion and often have associated congenital abnormalities and comorbidities. This perspective is a first step in gathering information to allow provision of informed counseling on the predicted outcomes of affected babies.