β‐thalassemia major is an inherited hemoglobinopathy that requires lifelong red blood cell transfusions and iron chelation therapy to prevent complications due to iron overload. Traditionally, ...β‐thalassemia has been more common in certain regions of the world such as the Mediterranean, Middle East, and Southeast Asia. However, the prevalence of β‐thalassemia is increasing in other regions, including Northern Europe and North America, primarily due to migration. This review summarizes the available data on the changing incidence and prevalence of β‐thalassemia as well as factors influencing disease frequency. The data suggest that the epidemiology of β‐thalassemia is changing: Migration has increased the prevalence of the disease in regions traditionally believed to have a low prevalence, while, at the same time, prevention and screening programs in endemic regions have reduced the number of affected individuals. Various approaches to prevention and screening have been used. Region‐specific prevention and treatment programs, customized to align with local healthcare resources and cultural values, have been effective in identifying patients and carriers and providing information and care. Significant challenges remain in universally implementing these programs.
Thalassemia syndromes are characterized by the inability to produce normal hemoglobin. Ineffective erythropoiesis and red cell transfusions are sources of excess iron that the human organism is ...unable to remove. Iron that is not saturated by transferrin is a toxic agent that, in transfusion-dependent patients, leads to death from iron-induced cardiomyopathy in the second decade of life. The availability of effective iron chelators, advances in the understanding of the mechanism of iron toxicity and overloading, and the availability of noninvasive methods to monitor iron loading and unloading in the liver, heart, and pancreas have all significantly increased the survival of patients with thalassemia. Prolonged exposure to iron toxicity is involved in the development of endocrinopathy, osteoporosis, cirrhosis, renal failure, and malignant transformation. Now that survival has been dramatically improved, the challenge of iron chelation therapy is to prevent complications. The time has come to consider that the primary goal of chelation therapy is to avoid 24-h exposure to toxic iron and maintain body iron levels within the normal range, avoiding possible chelation-related damage. It is very important to minimize irreversible organ damage to prevent malignant transformation before complications set in and make patients ineligible for current and future curative therapies. In this clinical case-based review, we highlight particular aspects of the management of iron overload in patients with beta-thalassemia syndromes, focusing on our own experience in treating such patients. We review the pathophysiology of iron overload and the different ways to assess, quantify, and monitor it. We also discuss chelation strategies that can be used with currently available chelators, balancing the need to keep non-transferrin-bound iron levels to a minimum (zero) 24 h a day, 7 days a week and the risk of over-chelation.
Thalassemia is among the most common monogenic diseases worldwide. Stem cell transplantation can be curative but is reserved for young patients, as probably gene therapy will be in the future. Adult ...thalassemia patients are treated with transfusion therapy and iron chelation, and improvements in the safety of transfusion protocols, use of iron chelation, monitoring of iron overload, and management of comorbidities have substantially prolonged survival, increasing the proportion of adult patients in the thalassemic population. However, older patients are more likely to develop multiple disease-related morbidities, including osteoporosis, endocrine disorders, liver disease, renal dysfunction, and cancer. Thus, the main objective of this article is to describe new challenges posed by the increasing life expectancy of patients with thalassemia, focusing on data from Italy where there is a well-documented history of thalassemia management. It is hoped that the mortality and morbidity benefits already seen in patients with thalassemia will continue to improve with ongoing advances in the quality of treatment.
Fyn is a tyrosine kinase belonging to the Src family (Src-Family-Kinase, SFK), ubiquitously expressed. Previously, we report that Fyn is important in stress erythropoiesis. Here, we show that in red ...cells Fyn specifically stimulates G6PD activity, resulting in a 3-fold increase enzyme catalytic activity (kcat) by phosphorylating tyrosine (Tyr)-401. We found Tyr-401 on G6PD as functional target of Fyn in normal human red blood cells (RBC), being undetectable in G6PD deficient RBCs (G6PD-Mediterranean and G6PD-Genova). Indeed, Tyr-401 is located to a region of the G6PD molecule critical for the formation of the enzymatically active dimer. Amino acid replacements in this region are mostly associated with a chronic hemolysis phenotype. Using mutagenesis approach, we demonstrated that the phosphorylation status of Tyr401 modulates the interaction of G6PD with G6P and stabilizes G6PD in a catalytically more efficient conformation. RBCs from Fyn-/−mice are defective in G6PD activity, resulting in increased susceptibility to primaquine-induced intravascular hemolysis. This negatively affected the recycling of reduced Prx2 in response to oxidative stress, indicating that defective G6PD phosphorylation impairs defense against oxidation. In human RBCs, we confirm the involvement of the thioredoxin/Prx2 system in the increase vulnerability of G6PD deficient RBCs to oxidation. In conclusion, our data suggest that Fyn is an oxidative radical sensor, and that Fyn-mediated Tyr-401 phosphorylation, by increasing G6PD activity, plays an important role in the physiology of RBCs. Failure of G6PD activation by this mechanism may be a major limiting factor in the ability of G6PD deficient RBCs to withstand oxidative stress.
Display omitted
•In red cells, Fyn acts as an oxidative sensor.•Fyn specifically stimulates G6PD activity by phosphorylating tyrosine (Tyr)-401.•In Fyn-/-mice, failure of G6PD activation increases red cell vulnerability against oxidation.•Fyn targeting G6PD protects Prx2 recycling, which is required to remove peroxides.
β-thalassemia, a hereditary blood disorder caused by defective synthesis of hemoglobin β globin chains, leads to ineffective erythropoiesis and chronic anemia that may require blood transfusions. ...Sotatercept (ACE-011) acts as a ligand trap to inhibit negative regulators of late-stage erythropoiesis in the transforming growth factor β superfamily, correcting ineffective erythropoiesis. In this phase II, open-label, dose-finding study, 16 patients with transfusion-dependent β -thalassemia and 30 patients with non-transfusion-dependent β-thalassemia were enrolled at seven centers in four countries between November 2012 and November 2014. Patients were treated with sotatercept at doses of 0.1, 0.3, 0.5, 0.75, or 1.0 mg/kg to determine a safe and effective dose. Doses were administered by subcutaneous injection every 3 weeks. Patients were treated for ≤22 months. Response was assessed as a ≥20% reduction in transfusion burden sustained for 24 weeks in transfusion-dependent β-thalassemia patients, and an increase in hemoglobin level of ≥1.0 g/dL sustained for 12 weeks in non-transfusion-dependent β-thalassemia patients. Sotatercept was well tolerated. After a median treatment duration of 14.4 months (range 0.6-35.9), no severe life-threatening adverse events were observed. Thirteen percent of patients reported serious but manageable adverse events. The active dose of sotatercept was ≥0.3 mg/kg for patients with non-transfusion-dependent β-thalassemia and ≥0.5 mg/kg for those with transfusion-dependent β-thalassemia. Of 30 non-transfusion-dependent β-thalassemia patients treated with ≥0.1 mg/kg sotatercept, 18 (60%) achieved a mean hemoglobin increase ≥1.0 g/dL, and 11 (37%) an increase ≥1.5 g/dL, sustained for ≥12 weeks. Four (100%) transfusion-dependent β-thalassemia patients treated with 1.0 mg/kg sotatercept achieved a transfusion-burden reduction of ≥20%. Sotatercept was effective and well tolerated in patients with β-thalassemia. Most patients with non-transfusion-dependent β-thalassemia treated with higher doses achieved sustained increases in hemoglobin level. Transfusion-dependent β-thalassemia patients treated with higher doses of sotatercept achieved notable reductions in transfusion requirements. This trial was registered at ClinicalTrials.gov with the number NCT01571635.
Sickle cell disease: a review for the internist Pinto, Valeria Maria; Balocco, Manuela; Quintino, Sabrina ...
Internal and emergency medicine,
10/2019, Letnik:
14, Številka:
7
Journal Article
Recenzirano
Odprti dostop
Sickle cell disease (SCD) is the most important hemoglobinopathy worldwide in terms of frequency and social impact, recently recognized as a global public health problem by the World Health ...Organization. It is a monogenic but multisystem disorder with high morbidity and mortality. Vaso-occlusion, hemolytic anemia and vasculopathy are the hallmarks of SCD pathophysiology. This review focuses both on “time-dependent” acute clinical manifestations of SCD and chronic complications commonly described in adults with SCD. The review covers a broad spectrum of topics concerning current management of SCD targeted at the internists and emergency specialists who are increasingly involved in the care of acute and chronic complications of SCD patients.
Mutations in more than 70 genes cause hereditary anemias (HA), a highly heterogeneous group of rare/low frequency disorders in which we included: hyporegenerative anemias, as congenital ...dyserythropoietic anemia (CDA) and Diamond‐Blackfan anemia; hemolytic anemias due to erythrocyte membrane defects, as hereditary spherocytosis and stomatocytosis; hemolytic anemias due to enzymatic defects. The study describes the diagnostic workflow for HA, based on the development of two consecutive versions of a targeted‐NGS panel, including 34 and 71 genes, respectively. Seventy‐four probands from 62 unrelated families were investigated. Our study includes the most comprehensive gene set for these anemias and the largest cohort of patients described so far. We obtained an overall diagnostic yield of 64.9%. Despite 54.2% of cases showed conclusive diagnosis fitting well to the clinical suspicion, the multi‐gene analysis modified the original clinical diagnosis in 45.8% of patients (nonmatched phenotype‐genotype). Of note, 81.8% of nonmatched patients were clinically suspected to suffer from CDA. Particularly, 45.5% of the probands originally classified as CDA exhibited a conclusive diagnosis of chronic anemia due to enzymatic defects, mainly due to mutations in PKLR gene. Interestingly, we also identified a syndromic CDA patient with mild anemia and epilepsy, showing a homozygous mutation in CAD gene, recently associated to early infantile epileptic encephalopathy‐50 and CDA‐like anemia. Finally, we described a patient showing marked iron overload due to the coinheritance of PIEZO1 and SEC23B mutations, demonstrating that the multi‐gene approach is valuable not only for achieving a correct and definitive diagnosis, but also for guiding treatment.
Recent advances in the management of thalassemia have significantly improved life expectancy and quality of life of patients with this hemoglobinopathy, with a consequent increase in their ...reproductive potential and desire to have children.
We describe the methods of conception and delivery, as well as the course and outcome of pregnancy including transfusions, iron overload and chelation in 46 women with thalassemia major (58 pregnancies) and in 11 women with thalassemia intermedia (17 pregnancies). Conception was achieved after gonadotrophin-induced ovulation in 33 of the women with thalassemia major and spontaneously in all of those with thalassemia intermedia.
Among the women with thalassemia major, 91% of the pregnancies resulted in successful delivery of 45 singleton live-born neonates, five sets of twins and one set of triplets. No secondary complications of iron overload developed or worsened during pregnancy. When considering only the singleton pregnancies, the proportion of babies with intrauterine growth retardation did not differ from that reported in the general Italian population. The high prevalence of pre-term births (32.7%) was mostly related to multiple pregnancies and precautionary reasons. Pregnancy was safe in most women with thalassemia major or intermedia. However, women with thalassemia intermedia who had never previously been transfused or who had received only minimal transfusion therapy were at risk of severe alloimmune anemia if blood transfusions were required during pregnancy.
Provided that a multidisciplinary team is available, pregnancy is possible, safe and usually has a favorable outcome in patients with thalassemia. In women with hypogonadotropic hypogonadism, gonadal function is usually intact and fertility is usually retrievable.
Methemoglobinemia is a rare disorder associated with oxidization of divalent ferro‐iron of hemoglobin (Hb) to ferri‐iron of methemoglobin (MetHb). Methemoglobinemia can result from either inherited ...or acquired processes. Acquired forms are the most common, mainly due to the exposure to substances that cause oxidation of the Hb both directly or indirectly. Inherited forms are due either to autosomal recessive variants in the CYB5R3 gene or to autosomal dominant variants in the globin genes, collectively known as HbM disease. Our recommendations are based on a systematic literature search. A series of questions regarding the key signs and symptoms, the methods for diagnosis, the clinical management in neonatal/childhood/adulthood period, and the therapeutic approach of methemoglobinemia were formulated and the relative recommendations were produced. An agreement was obtained using a Delphi‐like approach and the experts panel reached a final consensus >75% of agreement for all the questions.
PDF
