Non-coding segments of DNA are those segments that do not code for any amino acids or protein. Many non-coding DNA sequence or region plays an important role in controlling gene activity which determines when any gene will turn off and turn on.
For example mutation in enhancer element that regulates the SOX9 gene can a disorder called isolated Pierre Robin sequence which can cause abnormalities in face and head. Apart from enhancer mutation can affect other regulatory sequence like promoter, silencer which can cause several types of cancer because they affect cell cycle negatively.
Several mutations have been shown to be connected to the development of cancer. Mutations in the front area of the gene which controls the length of telomeres, can trigger cancer. Telomeres decide how many times a cell can divide and every time a cell divides the telomeres becomes shorter meaning at a stage the telomeres are so short that the cells can not longer divide. However, when mutation occurs in the region before the gene it makes it active and extends the length of telomeres in an abnormal way making cells to keep dividing itself leading to a tumour.
Also when mutation and replication occurs in non coding regions, it leads to copying of unwanted genes that will alter the protein structure and thus leads to a disease condition and even cancer.
