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Beta Thalassemia (4)
Beta thalassemia major was first described by a Detroit pediatrician,
Thomas Cooley, in 1925. The clinical picture he described is prevalent
today in countries without the necessary resources to provide patients
with chronic transfusions and desferoxamine therapy. Children who have
untreated thalassemia major have ineffective erythropoiesis, decreased
red cell deformability, and enhanced clearance of defective red cells
by macrophages (immune system cells). The result is a very hypermetabolic
bone marrow with thrombocytosis,
leukocytosis
and microcytic anemia in the young child prior to the enlargement of their
spleen. At presentation they have almost 100% percent Hgb F (these cells
have a longer life span due to a balanced globin ratio, as c
rather than b, globin is present Hgb F).
These children have little or no Hgb A2 and a low reticulocyte
count. The diagnosis can be confirmed by demonstrating thalassemia trait
in both parents, by globin biosynthetic ratios, or by beta gene screening.
Beta gene screening identifies the most common and some uncommon mutations,
but not all mutations. An electrophoresis showing only Hgb F, a complete
blood count and a smear will generally be diagnostic. In most states,
these children will be discovered by state screening or occasionally by
the obstetrician who makes a diagnosis of thalassemia trait in the mother
and obtains a family history of thalassemia or anemia in both parents
prior to the birth of the baby.
Children who have untreated thalassemia generally die in the first decade
of life from anemia and septicemia,
and may suffer from pathologic fractures. When palliative transfusions
are introduced, children live into their late teens, but eventually succumb
to heart failure if iron overload is not treated. But with the introduction
of frequent chronic transfusion therapy and the use of subcutaneous desferoxamine,
children are now surviving into adulthood. The longevity of patients who
are compliant with their Desferal therapy or who have received bone marrow
transplantation is not known. <back>
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