This is an inherited (run in the family) anemia in which the body produces the abnormal hemoglobin in the red blood cells. Hemoglobin normally carries oxygen. The production of abnormal hemoglobin results in red blood cells being destroyed, which lead to anemia.
Symptoms are typical seen in anemia such as fatigue/malaise/shortness breath due to the lack of oxygen, pallor/pale skin/swelling due to the lack of blood supply to the body. The characteristic symptoms t of thalassemia are that some patients have bone deformities (particular facial bones) and jaundice (yellowish skin).
When you feel unexplained tiredness with pale skin and other anemia symptoms, please go to see your doctor for diagnosis and treatments.