Beta Thalassemia (cont.)

What is Mediterranean anemia?

The gene for beta thalassemia is not evenly distributed among peoples. It is, for example, relatively more frequent in people of Italian and Greek origin, both of which are peoples from the Mediterranean. Because of this, thalassemia major has been called Mediterranean anemia.

The name thalassemia was coined at the University of Rochester in upstate New York by the Nobel Prize-winning pathologist George Whipple and the professor of pediatrics William Bradford from the Greek thalassa for sea and -emia, meaning the blood. Thalassemia means "sea in the blood." But for the Greeks, the sea was the Mediterranean, so thalassemia also conveys the idea of the Mediterrranean in the blood.

The reason that the gene for beta thalassemia is relatively common, for example, among people of Italian and Greek origin is that parts of Italy and Greece were once full of malaria. The presence of thalassemia minor (like sickle cell trait in Africa) afforded protection against malaria, and therefore, this gene thrived.

What is the genetic pattern of inheritance of beta thalassemia?

The pattern of genetic transmission of beta thalassemia (and sickle cell disease) was deciphered by James V. Neel when he was at the University of Rochester (he later went to Michigan). Dr. Neel recognized that the parents of children with thalassemia major had thalassemia minor with one beta thalassemia gene. When these parents had children, they have a 25% chance of having a thalassemia major child (with both genes for beta thalassemia), a 50% chance of having children with thalassemia minor (with only one gene for beta thalassemia), and a 25% chance of having a child without thalassemia major or minor (with both genes for normal beta chains). This form of inheritance is medically referred to as an autosomal recessive pattern.

Next: The diagnosis of thalassemia major and minor »

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