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thalassemia and iron overload

Posted by iskanbasal on September 22, 2007

“Thalassemia is an inherited blood disease characterized by the under production of normal hemoglobin, the oxygen-carrying protein in red blood cells. People with severe forms of thalassemia often suffer from anemia, a condition in which the body tissues do not get enough oxygen from the blood, and often require blood transfusions.”

I understood that blood transfusions are the principal cause of iron overload in this disease and i learned the use of deferoxamine ( Desferal is an iron-chelating agent) to chelate the excess of iron in the tissues of patients with thalassemia. The accumulation of iron in the heart is an important cause of death in thalassemia patients as I studied in my hematology course. Now scientists have discovered an another cause of iron excess in thalassemia:

“Blood transfusions contribute to iron overload in people with thalassemia, but these people also suffer from iron overload independent of blood transfusions. Excess iron causes damage to many organs including the heart and liver, and diabetes can develop in severe cases. Patients with thalassemia often require treatment to remove the excess iron to prevent tissue damage.”

Liver normally produces a protein called Hepcidin which regulates the absorption of iron in the intestine. In thalasemia the extremely active bone marrow produce a peptide that suppress the hepcidin in the liver; as a consequence there is a more uptake of iron in the intestine and thus, its overload:

“Thalassemia patients absorb too much iron from food due to abnormally low levels of a small peptide, called hepcidin, which regulates iron uptake from the gut. People with thalassemia should produce hepcidin at high levels. Instead, these patients have reduced levels of hepcidin. This confounded the authors and led them to ask if the low levels of hepcidin were somehow caused by the underlying problem in thalassemia -abnormal development of red blood cells.”

“Since erythroblasts need iron to make hemoglobin, we reasoned that the increased number of erythroblasts in thalassemia may send stronger messages to the liver to suppress hepcidin and thereby absorb more iron even in the condition of iron overload,” says the study’s lead author, Toshihiko Tanno, Ph.D., an investigator in Miller’s laboratory in the NIDDK’s Division of Intramural Research.”

News from the NIH : released in August 26, 2007 .

(Escuse me my English errors).

here below is the nature medicine citation of the paper:

 

High levels of GDF15 in thalassemia suppress expression of the iron regulatory protein hepcidin
JA – Nat Med
PY – 2007/09//print
VL – 13
IS – 9
SP – 1096
EP – 1101
SN – 1078-8956
UR http://dx.doi.org/10.1038/nm1629

 

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