Disease Information for Hemoglobin H disease

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Clinical Manifestations
Signs & Symptoms
Mental Deficiency Child
Disease Progression
Course/Chronic disorder
Course/Chronic only
Demographics & Risk Factors
Population Group
Child
Population/Pediatrics population
Sex & Age Groups
Population/Child
Population/Child-Infant Only
Population/Children/all
Laboratory Tests
Microbiology & Serology Findings
Reticulocytosis
Microbiology & Serology Findings
Reticulocytosis
Abnormal Lab Findings (Non Measured)
Fast-migrating hemoglobin/electrophoresis (Lab)
Hemoglobin electrophoresis abnormal (Lab)
Hypochromia/blood smear (Lab)
Microcytes/small RBCs on Blood smear
Microcytosis/microcytic anemia (Lab)
Abnormal Lab Findings - Decreased
Hematocrit (Lab)
Hemoglobin (Lab)
MCV/Mean Corpuscular Volume (Lab)
RBC/Red Blood Count (Lab)
RDW/Red cell size variance (Lab)
Reticulocytes (Lab)
Abnormal Lab Findings - Increased
Poikilocytes (Lab)
Polychrome RBCs (Lab)
RDW/Red cell size variance (Lab)
Reticulocytes (Lab)
Target cells (Lab)
Associated Diseases & Rule outs
Associated Disease & Complications
Anemia
Mental retardation
Disease Mechanism & Classification
Class
CLASS/Erythrocyte disorder (ex)
CLASS/Hematologic (category)
Pathophysiology
Pathophysiology/Gene locus 16pter-p13.3
Pathophysiology/Gene locus Chromosome 16
Pathophysiology/Gene Locus Identified/OMIM database
Pathophysiology/Genomic indentifiers (polymorphism/snip/mutations)
Process
PROCESS/Hereditofamilial (category)
PROCESS/Hemoglobinopathy disorder (ex)
PROCESS/Molecular/hematologic disorder (ex)
Treatment
Drug Therapy - Indication
RX/Folic/Folinic acid (Leukovorin)
Definition

A disorder characterized by reduced synthesis of the alpha chains of hemoglobin. Hemoglobin H disease [three gene alpha thalassemia] The loss of three alpha genes produces a serious hematological problem (three-gene deletion alpha thalassemia). Patients with this condition have a severe anemia, and often require blood transfusions to survive. The severe imbalance between the alpha chain production (now powered by one gene, instead of four) and beta chain production (which is normal) causes an accumulation of beta chains inside the red blood cells. Normally, beta chains pair only with alpha chains. With three-gene deletion alpha thalassemia, however, beta chains begin to associate in groups of four, producing an abnormal hemoglobin, called "hemoglobin H". The condition is called "hemoglobin H disease". Hemoglobin H has two problems. First it does not carry oxygen properly, making it functionally useless to the cell. Second, hemoglobin H protein damages the membrane that surrounds the red cell, accelerating cell destruction. The combination of the very low production of alpha chains and destruction of red cells in hemoglobin H disease produces a severe, life-threatening anemia. Untreated, most patients die in childhood or early adolescence.

Hemoglobin H disease. These patients have lost three alpha globin genes. The result is a severe anemia, with small, misshapen red cells and red cell fragments. These patients typically have enlarged spleens. Bony abnormalities particularly involving the cheeks and forehead are often striking. The bone marrow works at an extraordinary pace in an attempt to compensate for the anemia. As a result, the marrow cavity within the bones is stuffed with red cell precursors. These cells gradually cause the bone to "mold" and flair out. Patients with hemoglobin H disease also develop large spleens. The spleen has blood forming cells, the same as the bone marrow. These cells become hyperactive and overexpand, just as those of the bone marrow. The result is a spleen that is often ten-times larger than normal. Patients with hemoglobin H disease often are small and appear malnourished, despite good food intake. This feature results from the tremendous amount of energy that goes into the production of new red cells at an extremely accelerated pace. The constant burning of energy by these patients mimics intense aerobic exercise; exercise that goes on for every minute of every day.

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External Links Related to Hemoglobin H disease
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NGC (National Guideline Clearinghouse)
Medscape (eMedicine)
Harrison's Online (accessmedicine)
NEJM (The New England Journal of Medicine)
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