Thalassemia is caused by a gene that reduces the production of hemoglobin. Hemoglobin carries oxygen inside red blood cells. The lack of hemoglobin causes destruction of the red blood cells, which results in anemia.

Genes control the functions inside a cell. Special genes control how cells divide and grow. Cancer occurs when the damaged genes stimulate the cell to multiply out of control. The exact cause for this damage is unknown.

Examples:

• DNA
• Genes on chromosomes
• Cancer cells
• Cancer cell division