How has the genetic evolution of Thalassemia affected certain regions of the World?

Genetic Information

Resistance To Malaria

Mutation occurred to protect from Malaria

Children with alpha thalassemia adapted to loss of red blood cells associated with malaria

Individuals who survive malaria, pass on their SEA allele to offspring

Geographical Information

Consanguineous Marriage

Meaning

Marriage between individuals who are closely related (Usually first or second cousins, rarely incest)

Deletions of HBA1 and/or HBA2 happens to occur in most cases of αlpha-thalassemia

Beta thalassemia is caused by mutations in the hemoglobin beta (HBB) gene

Passed from parent to offspring

Autosomal Recessive

Chromosomes Affected

Alpha Thalassemia: Hemoglobin genes
HBA 1 and HBA 2 are affected on chromosome 16

Beta Thalassemia: Chromosome 11 is affected

Theorized that without malaria, genetic gene pool of thalassemia would not carry on

Thalassemia changes the shaping of the hemoglobin, therefore prevents malarial parasites from binding to red blood cells

In high frequency countries

Results in High Gene Pool allele for thalassemia

Increases gene frequency for recessive disorders

Alpha-Thalassemia is most common in Mediterranean countries, South Asia South-East Asia, and Africa

Thalassemia Most Common

Malaria is most common in Africa, South Asia, Southeast Asia, and the Middle East

Malaria Most Common

Genetic Bottleneck

World War 2

After the second World War, population of non-thalassemia carriers has reduced significantly

Resulted in higher quantities of individuals who are affected with thalassemia or are carriers