Sunday, 27 May 2012

Melanoma - Somatic Mutation

Melanoma, Genetically Mutated cells

Melanoma is one of the most aggressive forms of skin cancer, which claimed the lives of more than 8700 people in 2010 with more than 70000 diagnosed with the disease. In recent years, the number of fatalities has risen dramatically, causing concern for the general public and the scientific community.

With such high numbers of diagnoses and deaths, scientists are under pressure to locate and identify pathways that are directly involved in the development of melanoma cells.

With the completion of the human-genome project in 2003 identification of specific genes enabled scientists to study genetic alterations of melanoma in crazy ways that weren’t possible before.

What the human genome project allows, that once didn’t exist, is the identification of all 25000 human genes, determination of all 3 billion base pairs that make up human DNA and the ability to store this information in a database that can be readily accessed.

So, Melanoma, like many other diseases is caused by a genetic alteration in specific cells. Genes are what make an organism unique. You will never find two people with the same gene sequence.

Research has shown that melanoma originates in things called melanocytes and when these genetically altered, the melanoma cell simply evades the body’s tumor surveillance system. As we all know, 4 nucleotides make up DNA; Adenine with Thymine, Cytosine with Guanine and what happens during the genetic alteration is a substitution between Cytosine and Thymine.

This happens due to what’s called Ultra Violet light. It oscillates at a shorter wavelength than Visible Light and therefore has a higher energy output and what happens is you get reactive particles, like oxygen, and you get replication errors in the Cytosine and Thymine base pairs.
The genes affected are called tumor suppressors, the mutated cells that would usually suppress any developing tumor is incapable of doing that and hence the tumor grows.

Now that the mutation pathway has been determined, identification of somatic mutation can be tested. The process involves taking a sample of tumor cells and normal tissue cells and cross running the sequencing to locate the mutation.

In previous studies, individual candidate genes (genes suspected of being involved in expression of diseases) were examined but this was shown to be slow and inefficient. With the completion of the human genome project, entire ‘candidate families’ in the hundreds can be investigated simultaneously.  One of the first families to be completely sequenced was the Tyrosine kinase family. Several members of this family have been directly correlated to the formation of tumors along with many more.

The point being made here is that melanoma arises from a complex array of genetically altered genes, which are only beginning to be understood. With advancements in genetics such the Human Genome Project and DNA sequencing, disease origins like melanoma are no longer scientific mysteries, but rather genetic projects designed to identify and classify genetic subunits. Only through identification and classification can treatments be created, and this is all thanks to genetics.

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