How do translocations cause problems in cells?
When a translocation occurs, it interferes with the genes. Genes can be lost or new ones formed by the fusion of two pre-existing genes at the point at which the translocation occurs. If the lost gene was one which was important for normal cell division or which would prevent a cell from becoming cancerous then a tumour might develop. In the case of Ewing’s sarcoma, the translocation joins two genes together, one called EWS, the other called FLI1, to form a ‘fusion gene’ called EWS-FLI1. Fusion genes are common in many cancers but EWS-FLI1 is specific to the Ewing’s sarcoma Family of Tumours and can therefore help with the diagnosis. The EWS-FLI1 fusion gene instructs the cell to make EWS-FLI1 fusion protein. This protein is thought to affect further instructions in the cell by switching other genes on or off. Changes in the cell’s instructions can cause cells to become malignant. There are also other chromosomal abnormalities and genetic mutations in many Ewing’s cases. The changes in
