By Malak Sayed
What is thalassemia?
Types of thalassemia and how it is inherited
Thalassemia is an inherited blood disorder that causes your body to have less hemoglobin than usual. Thalassemia can cause anemia, leaving you fatigued. If you have mild thalassemia, you might not need treatment. But more severe forms might need regular blood transfusions. You can take steps to cope with fatigue, such as choosing a healthy diet and exercising. There are several types of thalassemia. The signs and symptoms you have depend on the type and severity of your condition.
Thalassemia signs and symptoms can include:
Fatigue, weakness, pale or yellowish skin, facial bone deformities, slow growth, abdominal swelling and dark urine.
Some babies show signs and symptoms of thalassemia at birth; others develop them during the first two years of life. Some people who have only one affected hemoglobin gene don't have thalassemia symptoms.
Types of thalassemia and how it is Inherited
When we talk about different “types” of thalassemia, we are talking about either one of two things: the specific part of hemoglobin that is affected (usually either “alpha” or “beta”), or the severity of thalassemia, which is noted by words like trait, carrier, intermediate, or major.
Hemoglobin carries oxygen to all cells in the body and is composed of two different parts: alpha and beta. When thalassemia is called “alpha” or “beta,” this refers to the part of hemoglobin that isn’t being made. If either the alpha or beta part is not made, there aren’t enough building blocks to make normal amounts of hemoglobin. Low alpha is called alpha thalassemia. Low beta is called beta-thalassemia.
When the words “trait,” “minor,” “intermediate,” or “major” are used, these words describe how severe the thalassemia is. A person who has thalassemia trait may not have any symptoms at all or may have only mild anemia, while a person with thalassemia major may have severe symptoms and may need regular blood transfusions.
Like the way traits for hair color and body structure are passed down from parents to children, thalassemia traits are passed from parents to children. The type of thalassemia that a person has depends on how many and what type of traits for thalassemia a person has inherited, or received from their parents. For instance, if a person receives a beta-thalassemia trait from his father and another from his mother, he will have a beta-thalassemia major. If a person received an alpha thalassemia trait from her mother and the normal alpha parts from her father, she would have an alpha thalassemia trait (also called alpha thalassemia minor). A thalassemia trait means that you may not have any symptoms, but you might pass that trait on to your children and increase their risk of having thalassemia.
Sometimes, thalassemia has other names, like Constant Spring, Cooley’s Anemia, or hemoglobin Bart's hydrops fetalis. These names are specific to certain thalassemia – for instance, Cooley’s Anemia is the same thing as beta-thalassemia major.
As clinical care of patients with thalassemia has improved and the patient population is ageing due to improved survival, new issues are evolving. These include long-term complications of infection with hepatitis C (HCV), thrombosis, and fertility. HCV and its consequences of fibrosis, cirrhosis and hepatocellular carcinoma (HCC) are prevalent. Increasing evidence of thrombotic risk in patients with thalassemia intermedia and thalassemia major is being reported in the literature. Further, the improved lifespan and clinical status of the thalassemia population has allowed the preservation of fertility and successful term pregnancies in some patients. Without exception, large-scale definitive trials addressing these problems in patients with thalassemia are still needed.
Worldwide, no patients get more red cell products than those with thalassemia major. The life-long need for transfusion renders patients vulnerable to transfusion-transmitted viral infections. HCV has emerged as the paramount risk. HCV was identified in 1989 and serologic screening of the blood supply was initiated in 1990. Data from the Registry of the Thalassemia Clinical Research Network (TCRN) demonstrate that this screening has successfully prevented new HCV infections via blood transfusion in younger patients with thalassemia major in North America. Only 5% of patients under age 15 (transfused since screening was available) are positive for HCV antibody or RNA, whereas the prevalence of HCV exposure in those over age 25 years is 70%.1 These results are encouraging. However, there are still hundreds of adults in North America and thousands worldwide with chronic HCV who are at risk for significant complications of liver fibrosis, cirrhosis and HCC. Additionally, in developing countries, the prevalence of HCV is as high as 63.8% in patients with thalassemia, including young patients.