HbH disease

Hemoglobinopties are disorders of blood cell structure and they may occur in many different ethnic groups, such as African, Asian, Mediterranean or Middle Eastern decent. There are two major types of Hemoglobinopaties:

1) Thalassemias : which are caused by quantitative deficiencies in the in the production of globulin chains which are used to produce hemoglobin. These defects generally produce anemia of varying degrees depending on severity.

2) Structural abnormalities of globin chain production causing a defect in the shape of the blood cells. Examples of this type of anemia would be an illness called Sickle Cell disease.

In this article we will talk about the Thalsemia syndromes and in particular about Hemoglobin H disease. In order for the human body to make normal hemoglobin, which is required to transport oxygen to all our vital organs, normal cells must have 4 alpha globin genes. In the Thalasemia disorders, there is a genetic defect or deletion in one to four of these alpha-globin genes on a chromosome #16. The severity of the syndrome is related to the number of gene deletions.

A) Silent Carrier: has one gene deletion. They are asymptomatic and have normal blood findings.

B) Alpha-Thalsemia Trait: 2 gene deletions, they have normal or slightly decreased hemoglobin (blood levels) causing a mild anemia.

C) Hemoglobin H disease: 3 gene deletions. They have mild to moderately severe anemia.

D) Hydrops fetalis: 4 gene deletions. They have severe intrauterine anemia, asphyxia, and usually expire shortly after birth.

In-patients with Hemoglobin H disease, or 3 gene deletions, these patents may be symptomatic and have secondary complications of hemolytic anemia. Patients with HbH disease can generally have moderate to severe anemia, with low hemoglobin levels of 7-10g/dl. Other common medical finding would be paleness, jaundice (or yellowness) large liver and spleen, increased susceptibility to infections, leg ulcers and pigment gallstones which occur after prolonged breakdown of red blood cells, can cause recurrent abdominal pain and may require surgery. Deficiency in Folic acid may also occur.

Complications that can occur in children with HbH disease are generally the result of intermittent exacerbation of their anemia, which may require repeated blood transfusions. These episodes of hemolytic anemia generally are precipitated by certain drugs or by a parvovirus infection. Usually patients with HbH disease can lead fairly normal lives with relatively few blood transfusions. Transfusion therapy is usually reserved for patients with severe anemia (usually less than 7g/dl) and with symptomatic anemia.

Another complication of this disease is the enlargement of the spleen with worsening of the anemia. Many times this requires the removal of the spleen itself, and then you have all the complications other than just that of surgery, which is the susceptibility to bacterial infections. Usually removal of the spleen is reserved for patients with symptoms of large spleen, as reflected by leukopenia (decreased white blood cell levels) thrombocytopenia (decreased platelet count) and worsening anemia or, in-patients who were previously stable and develop blood transfusion requirement.

What does the medical future of this child have in store for this adoptive family?

1) Usually patients with HbH disease can lead relatively normal lives.

2) They may require repeated blood transfusions, and after many years of therapy may result in a complication of iron overload.

3) Large spleen which may require its removal.

4) Susceptibility to bacterial infection after the removal of the spleen.

5) Many children are kept on prophylactic penicillin therapy to ward off infection.

6) Severe hemolytic anemia episodes which may easily be triggered in times of stress, infections with viral illness or may even by certain types of medications such as sulfur.

7) Gallstones and abdominal pain all secondary to pigment stone collection caused by prolonged destruction of red blood cells. Surgical removal of gallstones to alleviate the abdominal pain.

Now back to the original question that the parents say they are not carriers and are not ill. I believe that they are not ill but are more than likely both silent carriers of the disease or have the thalsemia trait or some combination of this. Because of the rules in genetics, it is possible to have three other children that are not ill with the severe form of the disease, but they may also be silent carriers or have the thalasemia trait. From the clinical description of this child's medical scenario, the diagnosis may be accurate. Good follow-up with a Pediatric Hematologist is essential to the management of this disease

Written By George Rogu M.D.

For Pre-adoption Medical Evaluations and Post-Adoption General care on Long Island New York, Visit us at our International Adoption Private Medical Clinic.

* Note: The information and advice provided is intended to be general information, NOT as advice on how to deal with a particular child's situation and or problem. If your child has a specific problem you need to ask your pediatrician about it -- only after a careful history and physical exam can a medical diagnosis and/or treatment plan be made.
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