RARE DISEASE
Hemoglobin H disease
Hemoglobin H disease
Hemoglobin H disease
Synonyms: Alpha-thalassemia intermedia, HbH disease
Synonyms: Alpha-thalassemia intermedia, HbH disease
Synonyms: Alpha-thalassemia intermedia, HbH disease
Drug discovery
1
drug
With orphan designation
Overview
Hemoglobin H Disease Overview
Hemoglobin H (HbH) disease is an intermediate alpha-thalassemia caused by inactivation of three alpha-globin alleles (HBA1/HBA2), leading to chronic hemolytic anemia, marked microcytosis, hypochromia, and variable hepatosplenomegaly [1][2][13]. Severity ranges from mild (deletional mutations) to transfusion-dependent anemia (non-deletional forms, e.g., HbH-Constant Spring) [5][10]. Complications include iron overload, growth delays, and cholelithiasis [1][4]. Management focuses on intermittent transfusions during infections/pregnancy, iron chelation, and avoidance of oxidant drugs [5][9]. Genetic counseling is critical for family planning [5][13].
Burden
Chronic anemia reduces quality of life, with fatigue, growth impairment, and complications (e.g., gallstones) [1][10].
Non-deletional HbH (~25% of cases) increases transfusion dependence, iron overload, and mortality risk [2][11].
Psychosocial and economic impacts due to lifelong monitoring and treatment [6][10].
Therapies
Transfusions: Indicated for acute anemia (Hb <6 g/dL) triggered by infections, oxidant exposure, or pregnancy [5][9].
Iron chelation: Required for transfusion-associated or non-transfusion-related iron overload [5][16].
Splenectomy: Reserved for hypersplenism or frequent transfusion needs (common in non-deletional HbH) [5][10].
Categories: rare endocrine diseases, rare genetic diseases, rare hematological diseases, rare transplant-related disorders
Research Papers
159 drug discovery papers about Hemoglobin H disease, with 2 first-in-class and 2 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
159 drug discovery papers about Hemoglobin H disease, with 2 first-in-class and 2 next-in-class emerging drug candidates forecasted to outperform the average preclinical success rate. Recent publications:
2026-07-10 | Thalassaemia.
The thalassaemia syndromes, which primarily include α-thalassaemia and β-thalassaemia, are a complex group of inherited disorders affecting haemoglobin production. They are prevalent throughout the most populated parts of the world and span a wide range of severity from mild to fatal. Advances in the management of these syndromes, including blood transfusion and iron chelation, have led to substantial improvements in the life expectancy and quality of life of many patients worldwide. Nevertheless, major forms of thalassaemia are still associated with chronic comorbidities and remain an important but neglected global health burden. Prevention and advances in the treatment and management of the thalassaemia syndromes rely on the early identification of people affected, either through prenatal or premarital screening or through newborn screening or testing at later stages in life. This depends on the availability of expertise, facilities and treatment options for patients. Fast and groundbreaking developments in disease-modifying and curative gene editing therapies are promising, but not without challenges in terms of costs, accessibility and uncertainties around their long-term benefits and safety. Better awareness, patient-centred approaches and coordinated strategies are needed to reduce current inequalities.
2026-06-23 | Chronic Red Cell Exchange for the Management of Alpha Thalassemia Major Complicated by Iron Overload.
Alpha thalassemia major is a severe hemoglobinopathy characterized by absent or markedly reduced alpha-globin production, necessitating lifelong blood transfusions. Chronic simple transfusions can lead to significant iron overload, often requiring iron chelation therapy. However, some patients are unable to tolerate chelation or chelation is insufficient, highlighting the need for alternative strategies for managing iron overload. This study is one of the first to evaluate the feasibility, safety, and efficacy of red blood cell exchange (RBCX) as a therapeutic option for managing iron overload while improving hemoglobin function in an alpha thalassemia major patient with iron overload despite chelation therapy. RBCX therapy was performed approximately every 3 weeks over 1 year, with frequent adjustment of exchange parameters to meet pre-transfusion target levels of functional hemoglobin. Serum ferritin levels, hemoglobin electrophoresis, and functional hemoglobin levels were tracked with each exchange transfusion. For each RBCX treatment, variant hemoglobins decreased by 3.8-fold (from 19.9% to 8.9%) and functional hemoglobin levels increased approximately 3.0 g/dL. RBCX was well tolerated and associated with a marked reduction in systemic iron burden, with serum ferritin declining 7.4-fold (86.4%) over 1 year of therapy, followed by a rise after cessation of RBCX. Cardiac iron remained within normal limits throughout the study period. In contrast, liver iron demonstrated a transient increase shortly after initiation of RBCX, but ultimately declined to levels below baseline after 1 year, even during a period in the absence of iron chelation. These findings suggest that RBCX exerts a meaningful effect on iron homeostasis and raises the possibility of a synergistic benefit when combined with iron chelation. This case highlights that RBCX is a viable therapeutic strategy to treat iron overload in patients with alpha thalassemia major.
2026-06-18 | Delayed Recognition and Significant Morbidity in Adults with Non-Transfusion-Dependent Thalassemia.
Non-transfusion-dependent thalassemia (NTDT) is characterized by variable degrees of anemia, ineffective erythropoiesis, and iron overload, with a heightened risk of age-related complications. However, the clinical profiles of patients who first present to thalassemia care in adulthood, as well as the gaps in management, are poorly described. In a multi-institutional study, we identified 82 patients with NTDT aged ≥18 years who were referred to three U.S. thalassemia centers between 2013 and 2023. Data were collected by manual chart review and included clinical history, laboratory tests, and imaging. The median age at initial visit was 36.8 years (range 18-74), and 37 (45%) of the patients had α-thalassemia, while 45 (55%) had β-thalassemia. Complications assessed included symptomatic anemia, prior splenectomy, extramedullary hematopoiesis, iron overload, pulmonary hypertension, cardiac arrhythmia, endocrine complications, and thrombosis. Iron overload was common, with 71% of available liver MRIs showing hepatic iron >5 mg Fe/g dry weight. Among patients with LIC >5 mg Fe/g, only 24.4% were on chelation at referral. Strikingly, 49% of patients were recommended to start regular transfusions following the consultation, predominantly for symptomatic anemia or complications of ineffective erythropoiesis. Patients with NTDT referred for initial comprehensive thalassemia care in adulthood had high rates of morbidities and undertreated iron overload. The criteria for initiating regular transfusions must be widely implemented to mitigate long-term complications and improve the quality of life of adults with NTDT.
2026-07-10 | Thalassaemia.
The thalassaemia syndromes, which primarily include α-thalassaemia and β-thalassaemia, are a complex group of inherited disorders affecting haemoglobin production. They are prevalent throughout the most populated parts of the world and span a wide range of severity from mild to fatal. Advances in the management of these syndromes, including blood transfusion and iron chelation, have led to substantial improvements in the life expectancy and quality of life of many patients worldwide. Nevertheless, major forms of thalassaemia are still associated with chronic comorbidities and remain an important but neglected global health burden. Prevention and advances in the treatment and management of the thalassaemia syndromes rely on the early identification of people affected, either through prenatal or premarital screening or through newborn screening or testing at later stages in life. This depends on the availability of expertise, facilities and treatment options for patients. Fast and groundbreaking developments in disease-modifying and curative gene editing therapies are promising, but not without challenges in terms of costs, accessibility and uncertainties around their long-term benefits and safety. Better awareness, patient-centred approaches and coordinated strategies are needed to reduce current inequalities.
2026-06-23 | Chronic Red Cell Exchange for the Management of Alpha Thalassemia Major Complicated by Iron Overload.
Alpha thalassemia major is a severe hemoglobinopathy characterized by absent or markedly reduced alpha-globin production, necessitating lifelong blood transfusions. Chronic simple transfusions can lead to significant iron overload, often requiring iron chelation therapy. However, some patients are unable to tolerate chelation or chelation is insufficient, highlighting the need for alternative strategies for managing iron overload. This study is one of the first to evaluate the feasibility, safety, and efficacy of red blood cell exchange (RBCX) as a therapeutic option for managing iron overload while improving hemoglobin function in an alpha thalassemia major patient with iron overload despite chelation therapy. RBCX therapy was performed approximately every 3 weeks over 1 year, with frequent adjustment of exchange parameters to meet pre-transfusion target levels of functional hemoglobin. Serum ferritin levels, hemoglobin electrophoresis, and functional hemoglobin levels were tracked with each exchange transfusion. For each RBCX treatment, variant hemoglobins decreased by 3.8-fold (from 19.9% to 8.9%) and functional hemoglobin levels increased approximately 3.0 g/dL. RBCX was well tolerated and associated with a marked reduction in systemic iron burden, with serum ferritin declining 7.4-fold (86.4%) over 1 year of therapy, followed by a rise after cessation of RBCX. Cardiac iron remained within normal limits throughout the study period. In contrast, liver iron demonstrated a transient increase shortly after initiation of RBCX, but ultimately declined to levels below baseline after 1 year, even during a period in the absence of iron chelation. These findings suggest that RBCX exerts a meaningful effect on iron homeostasis and raises the possibility of a synergistic benefit when combined with iron chelation. This case highlights that RBCX is a viable therapeutic strategy to treat iron overload in patients with alpha thalassemia major.
2026-06-18 | Delayed Recognition and Significant Morbidity in Adults with Non-Transfusion-Dependent Thalassemia.
Non-transfusion-dependent thalassemia (NTDT) is characterized by variable degrees of anemia, ineffective erythropoiesis, and iron overload, with a heightened risk of age-related complications. However, the clinical profiles of patients who first present to thalassemia care in adulthood, as well as the gaps in management, are poorly described. In a multi-institutional study, we identified 82 patients with NTDT aged ≥18 years who were referred to three U.S. thalassemia centers between 2013 and 2023. Data were collected by manual chart review and included clinical history, laboratory tests, and imaging. The median age at initial visit was 36.8 years (range 18-74), and 37 (45%) of the patients had α-thalassemia, while 45 (55%) had β-thalassemia. Complications assessed included symptomatic anemia, prior splenectomy, extramedullary hematopoiesis, iron overload, pulmonary hypertension, cardiac arrhythmia, endocrine complications, and thrombosis. Iron overload was common, with 71% of available liver MRIs showing hepatic iron >5 mg Fe/g dry weight. Among patients with LIC >5 mg Fe/g, only 24.4% were on chelation at referral. Strikingly, 49% of patients were recommended to start regular transfusions following the consultation, predominantly for symptomatic anemia or complications of ineffective erythropoiesis. Patients with NTDT referred for initial comprehensive thalassemia care in adulthood had high rates of morbidities and undertreated iron overload. The criteria for initiating regular transfusions must be widely implemented to mitigate long-term complications and improve the quality of life of adults with NTDT.
Access all drug discovery articles and probability of success in trials forecasts:
Access all drug discovery articles and probability of success in trials forecasts:
Drug Discovery Landscape
1 orphan drug designation for Hemoglobin H disease, including 1 approved therapy.
1 orphan drug designation for Hemoglobin H disease, including 1 approved therapy.
Drug | Therapy type | Regulator | Orphan designation | Approval | Sponsor |
|---|---|---|---|---|---|
Mitapivat sulfate [Pyrukynd] | small molecules | EMA | 2024-01-12 | 2026-05-22 | Agios Netherlands B.V. |
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