eamiru's Diary

Beta (β) thalassemias

Beta thalassemias are due to mutations in the HBB gene on chromosome 11 (Mendelian Inheritance in Man (OMIM) 141900), also inherited in an autosomal-recessive fashion. The severity of the disease depends on the nature of the mutation. Mutations are characterized as (βo) if they prevent any formation of β chains; they are characterized as (β+) if they allow some β chain formation to occur. In either case there is a relative excess of α chains, but these do not form tetramers: rather, they bind to the red blood cell membranes, producing membrane damage, and at high concentrations they form toxic aggregates.
Any given individual has two β globin alleles.

If only one β globin allele bears a mutation, the disease is called β thalassemia minor (or sometimes called β thalassemia trait). This is a mild microcytic anemia. In most cases β thalassemia minor is asymptomatic, and many affected people are unaware of the disorder. Detection usually involves measuring the mean corpuscular volume (size of red blood cells) and noticing a slightly decreased mean volume than normal.

If both alleles have thalassemia mutations, the disease is called β thalassemia major or Cooley's anemia. This is a severe microcytic, hypochromic anemia. Untreated, this progresses to death before age twenty. Treatment consists of periodic blood transfusion; splenectomy if splenomegaly is present, and treatment of transfusion-caused iron overload. Cure is possible by bone marrow transplantation.

Thalassemia intermedia is a condition intermediate between the major and minor forms. Affected individuals can often manage a normal life but may need occasional transfusions e.g. at times of illness or pregnancy, depending on the severity of their anemia.
The genetic mutations present in β thalassemias are very diverse, and a number of different mutations can cause reduced or absent β globin synthesis. Two major groups of mutations can be distinguished:

Nondeletion forms: These defects generally involve a single base substitution or small deletion or inserts near or upstream of the β globin gene. Most commonly, mutations occur in the promoter regions preceding the beta-globin genes. Less often, abnormal splice variants are believed to contribute to the disease.

Deletion forms: Deletions of different sizes involving the β globin gene produce different syndromes such as (βo) or hereditary persistence of fetal hemoglobin syndromes.

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Just some fact about my illness... lol... i'm the β thalassemia minor (or sometimes called β thalassemia trait) .... lol!