Question

Discuss how fusion genes can originate from chromosomal breaks, and how these fusion genes can lead to cancer?

Answer 1

Fusion genes are the types of genes that are formed by the combination or fusion of two independent genes that were normally functional previously. There are many reasons for the formation of fusion genes like translocation. deletion and chromosomal inversions or breaks. Chromosomal breakages occur due to many reasons like exposure to mutagens or any abnormal translocation among themselves. The breaks may allow one broken part of the chromosome to fuse or combine with any other chromosome that is unrelated. This allows unwanted translocations of the genes and thereby exchange of information. This leads to fusion of the unrelated or maybe sometimes related genes that can lead to many forms of human neoplasia.

Fusion genes is the fusion of mostly unrelated genes. A very clear example of the fusion gene producing cancer is the formation of Philadelphia chromosome that is caused by the fusion of genes in chromosome 22 that creates the BCR/ABL1 protein causing leukaemia. The fusion genes causes disruption of the regulatory seuqences and leads to the oncogenic functions of the gene functions that would allow formation of mild tumors or even advanced cancers. The fusion partners cause upregulation of most of the onogenic proteins that would lead to the formation of cancer.