Thalassemia is an inherited blood disorder in which your body has less hemoglobin and fewer red blood cells than normal. Because hemoglobin is the substance that allows your blood cells to carry oxygen, this condition causes extreme fatigue, weakness, growth delays and shortness of breath along with paleness and anemia. While thalassemia is a genetically inherited condition, many carriers of the gene may not be aware that they have it. Both parents must be carriers for the disease to be passed on to a child. Treatments for this condition range from dietary and lifestyle modifications for more mild cases to blood transfusions and bone marrow or stem cell transplantation for more severe ones.