8th of May, International Thalassemia Day
Derived from the Greek words for sea (θάλασσα) and blood (αίμα), thalassemias are a group of inherited, genetic blood disorders. Thalassemias occur when the production of hemoglobin, a protein that carries oxygen within the red blood cells (RBCs) is disrupted. A life-threatening disease, thalassemia is an autosomal recessive condition with over 100,000 affected babies being born every year1.
Hemoglobin consists of two parts, called alpha and beta proteins. When the production of one of these proteins is affected, it results in either alpha (α) or beta (β) thalassemia. Severity depends on the type of thalassemia and whether one has the ‘minor’, ‘intermedia’ or ‘major’ form – defined by the number of genes that are altered. α-thalassemia is most commonly found in Africa, Middle East and India, while β-thalassemia is more prevalent in the Mediterranean.
Symptoms and treatment of thalassemia vary depending on type and severity of the condition. In mild cases, symptoms might be non-existent and treatment is not required – carriers only have the risk of passing the affected gene to their offspring. In moderate to severe cases, symptoms may include fatigue, weakness, pale or yellowish skin, slow growth, abdominal swelling, dark urine and facial deformities2,3. Babies with the most severe cases may be born stillborn, die shortly after birth, or require lifetime treatment2. Untreated patients might show growth retardation, jaundice, poor musculature, skeletal changes and severe anemia2. Lifelong transfusion therapies and iron chelation procedures to remove the excess iron that is accumulated are needed for moderate and severe cases. The excess iron in the body is one of the most severe complications of thalassemia treatment, as it can damage the heart, liver and other internal organs2,4. Additionally, spleen enlargement may occur due to the spleen overworking to remove all the damaged RBCs and avoid possible infections. While spleen removal is an option, it leaves the body more prone to infections. Other complications of thalassemia treatment include hypothyroidism, heart failure, liver and gall bladder problems, and diabetes2,4. A bone marrow transplant to eliminate the need for lifelong blood transfusions might be a treatment option for severe cases, and gene therapy to correct the mutated gene could be applied in the future.
Even though thalassemia is more common in specific countries, its prevalence is worldwide due to population migration and intermarriage between different ethnic groups. Thalassemia carriers do not exhibit any symptoms and may be unaware of their genetic status, but their children have 50% chance of being carriers and 25% chance of being affected. Therefore, thalassemia carrier screening is one of the most widely performed genetic tests, and countries that are most affected by thalassemia have developed their own screening programs. These programs vary in being either mandatory or voluntary; being offered premaritally, preconceptionally or prenatally; and on the public education and counselling provided. Examples of successfully implemented thalassemia screening programs are those of Italy and Cyprus. The region of Sardinia introduced a voluntary screening program in premarital and antenatal couples in 1975 which saw the thalassemia incidence fall from 1:250 to 1:4000 in 20 years, a 95% incidence decrease5. A ‘quasi-mandatory’ premarital screening program in Cyprus, where 1 in 7 people is a carrier of β-thalassemia, was implemented in collaboration with the Greek Orthodox Church since the early 1980’s6. The thalassemia laboratory tests couples free of charge and issues them a certificate to confirm the testing – which is required if the couples wish to be married by the church. Genetic counselling and information on reproductive options, like pre-implantation genetic diagnosis (PGD) or prenatal testing, is offered to them if they have a risk of having an affected child. This led to a significant decrease in the birth of affected individuals that had a beneficial role in improving the treatment of thalassemic patients – otherwise there would have been a significant blood shortage in the island7.
In addition to carrier screening, prenatal detection of thalassemia is possible through non-invasive prenatal testing (NIPT), a simple and painless procedure that tests the fetus’s DNA through a maternal blood sample, and compares it to the maternal and paternal DNA to check for the genetic status. Nowadays, NIPT is routinely used for chromosomal aneuploidies as it provides the expecting parents with information early, reassures them, and allows them to take informed decisions. Its use in monogenic disorders, like thalassemia, is novel and provides an alternative option to the more expensive PGD. Confirmation of high-risk pregnancies by invasive procedures, like chorionic villi sampling or amniocentesis is recommended.
Every year, 8th of May is celebrated as the International Thalassemia Day. The aims are to spread knowledge about thalassemia and raise awareness about a disease that used to be universally fatal, but now has excellent prognosis due to medical, social and political collaboration.
The VERAgene NIPT can detect thalassemia, along with 49 other monogenic disorders, 8 aneuploidies and 4 microdeletions from the 10th week of pregnancy. To learn more please visit https://www.nipd.com/veragene/. NIPT results, possible next steps and clinical management should always be fully discussed with your healthcare provider.
- National Human Genome Research Institute (2013), https://www.genome.gov/Genetic-Disorders/Thalassemia
- May Clinic (2016), https://www.mayoclinic.org/diseases-conditions/thalassemia/symptoms-causes/syc-20354995
- Rare Diseases (2015), https://rarediseases.info.nih.gov/diseases/7756/thalassemia
- Kids Health (2015), https://kidshealth.org/en/parents/beta-thalassemia.html
- Mitchell et al. (1996) ‘Twenty-year outcome analysis of genetic screening programs for Tay-Sachs and b-thalassemia disease carriers in high schools’. American Journal of Medical Genetics; 59: 793-798.
- Thalassaemia International Federation (2019), https://thalassaemia.org.cy/about/thalassaemia/
- Cousens E. et al. (2010) ‘Carrier screening for beta-thalassaemia: a review of international practice’. European Journal of Human Genetics, 18: 1077-1083.