Thalassemia Prevalence

Thalassemia affects approximately 4.4 of every 10,000 live births throughout the world. It causes males and females to inherit the relevant gene mutations equally because it follows an autosomal pattern of inheritance with no preference for gender.

Approximately 5% of the worldwide population has a variation in the alpha or beta part of the haemoglobin molecule, although not all of these are symptomatic and some are known as silent carriers. In fact, only 1.7% of the global population has signs as a result of the gene mutations, known as a thalassemia trait.

However, particular ethnic groups are more likely to be affected and 5-30% of the population may be symptomatic among these groups.

Alpha-Thalassemia

Alpha-thalassemia is particularly common among populations of Southeast Asian descent, and there are a high number of carriers in Sub-Saharan Africa and Western Pacific regions. The prevalence of different population groups according to geographical area of the world is:

• America: 0-5% of the population has a thalassemia trait, up to 40% may be a genetic carrier
• Eastern Mediterranean: 0-2% of the population has a thalassemia trait, up to 60% may be a genetic carrier
• Europe: 1-2% of the population has a thalassemia trait, up to 12% may be a genetic carrier
• Southeast Asia: 1-30% of the population has a thalassemia trait, up to 40% may be a genetic carrier
• Sub-Saharan Africa: 0% of the population has a thalassemia trait, up to 50% may be a genetic carrier
• Western Pacific: 0% of the population has a thalassemia trait, up to 60% may be a genetic carrier

Beta-Thalassemia

Beta-thalassemia is most common among populations of Mediterranean, African and South Asian ancestry. The prevalence of different population groups according to geographical area of the world is:

• Americas: 0-3% of population is affected by a gene mutation
• Eastern Mediterranean: 2-18% of population is affected a gene mutation
• Europe: 0-19% of population is affected a gene mutation
• Southeast Asia: 0-11% of population is affected a gene mutation
• Sub-Saharan Africa: 0-12% of population is affected a gene mutation
• Western Pacific: 0-13% of population is affected a gene mutation

Populations at Risk

Both alpha- and beta-thalassemia are more prevalent in tropical and subtropical regions of the world, particularly where malaria is or has been endemic. Although the reason for this is not clearly established, this is thought to be because carriers of the gene mutation have a degree of protection against malaria.

The southern regions of Italy and Greece are the most likely areas to be affected in Europe and countries to the north of the continent of Africa. The Maldives has a particularly high prevalence of thalassemia in Asia (16% of the population), alongside other countries with tropical climates such as India and Thailand.

Related Mortality

All types of thalassemia can be fatal in some cases, particularly when there are multiple gene mutations that affect the production of the globin chains. In 2013, 25,000 deaths were attributable to thalassemia, which was an improvement upon the 36,000 deaths recorded in 1990.

References

• http://www.ironhealthalliance.com/disease-states/thalassemia/epidemiology-and-pathophysiology.jsp
• http://www.who.int/bulletin/volumes/86/6/06-036673/en/
• https://www.ncbi.nlm.nih.gov/pubmed/25530442