Difference between revisions of "Genomics"
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Revision as of 13:49, 12 April 2017
Genomics is a scientific field focused on the study of genomes and their structure, functions, and evolutionary history [1]. A genome is the complete set of DNA that is present in each cell of a living organism. The genome is broken down into individual genes, each of which encodes a specific protein. Organisms have huge numbers of proteins that perform a variety of diverse biological functions. Genes are encoded by a sequence of 4 different nucleotide bases, Adenine (A), Thymine (T), Cytosine (C), and Guanine (G). Mutations or changes in this genetic code can cause defects in protein production that can lead to various disease conditions from cancer to sickle cell anemia [2]. In contrast to genetics, which tends to focus on the functions of single genes, genomics considers the full genome and larger gene networks and often observers variations at the population level. The mapping and modeling of genomes has wide implications for the fields of medicine, molecular biology, pharmaceutical sciences, and more. Advances in DNA sequencing could change the way that many diseases are approached and treated.
Contents
History
Early DNA Sequencing
After the proposal of the now accepted model of DNA structure by James Watson and Francis Crick in 1953, many efforts were made to find methods to effectively sequence DNA [3]. The first efficient method for sequencing larger pieces of genomic DNA was developed by Frederick Sanger in the mid-1970s and became known as the Sanger Method or chain-termination method [4]. This system combines the use of DNA polymerase, the enzyme that forms double-stranded DNA from a single-stranded template, with dideoxynucleotides that prevent further strand elongation once they are added. This will form strands of different length at each nucleotide position that can then be separated using gel electrophoresis. These fragments can then be assembled into a completed DNA sequence.
Advancements in Sequencing
In 1986, a major advancement was made to Sanger sequencing by the company Applied Biosystems, who optimized the Sanger Method using fluorescent dyes [5]. Now, each dideoxynucleotide was labeled with a different color dye. This allowed for all of the DNA fragments to be run in the same lane and be read by a machine to determine the DNA sequence based on the sequence of the fragments' fluorescence, greatly improving sequencing efficiency.
The Human Genome Project
The Human Genome Project started in the mid-1980s with the goal to determine the DNA sequence and define the function of every gene in the human genome. The project was the largest collaborative biological research undertaking in history and was deemed complete in 2003. The data has been made available to the public and has proven invaluable for uses ranging from determining mutations involved in certain cancers to designing more effective medications by improving gene targeting [6].
Uses of Genomics
Genomics allows scientists to study large data sets regarding gene and protein interactions to better understand how these interactions generate different conditions or phenotypes [7]. The study of these data also allow researchers to better understand how small changes in the genome can cause major effects on the body of an organism. One common subject of study are single nucleotide polymorphisms or SNPs. These are single nucleotide changes at a specific point in the genome that occur at a significant level in a population (>1%) [8]. The study of SNPs can improve our understanding of what sort of effects these mutations can have on a wider population level such as slightly increasing the likelihood of developing a certain kind of cancer. Other topics of study include epigenetics, which is the study of how mechanisms other than the DNA code itself can generate heritable traits [9]. These can include modifications to the histones such as methylation that change that way DNA is packaged and can affect gene expression without directly impacting the DNA code itself [10].
Ethical Issues
As genetic sequencing technology continues to advance, the possibility of having someone's genome be a basic part of their medical record is becoming closer to reality. Many fear that undergoing genetic testing will lead to discrimination based on their genome. In 2008, the government based the Genetic Information Nondiscrimination Act (GINA) which prevents both health insurance providers and employers from discriminating (through raised costs, refusal to provide coverage, hiring/firing, etc.) based on genetic information or family history of conditions [11]. Over 1,800 charges have been filed under the GINA as of the end of 2016 with 121 reaching settlements [12].
Genetic testing, particularly in-home genetic testing, is becoming more common as we move into the future. But as of now, most genetic tests are not regulated by the FDA and as such, the claims of the makers of these tests have little to no external validation [13]. In 2010, the FDA announced plans to expand their regulation to include all of these tests but that expansion has yet to take place [14]. While the FDA regulates genetic tests that are packaged and sold as "kits," a group of associated reagents that is sold to many different labs, they have established limited regulation over laboratory-developed tests (LDTs) in which genetic samples are collected and sent to a single lab for processing [15]. The lack of oversight of these companies could cause issues as more private companies such as 23andMe begin to use these kinds of genetic tests to generate profit.
See Also
References
- ↑ What is Genomics?
- ↑ Specific Genetic Disorders
- ↑ Nature: Watson and Crick, 1953
- ↑ PNAS: Sanger et al., 1977
- ↑ Nature: DNA Sequencing Technologies
- ↑ Wikipedia: The Human Genome Project
- ↑ Applications of Genomics
- ↑ Single Nucleotide Polymorphism
- ↑ Applications of Genomics
- ↑ Epigenetics
- ↑ Genetic Discrimination
- ↑ Equal Employment Opportunity Commission: Genetics
- ↑ Regulation of Genetic Tests
- ↑ Regulation of Genetic Tests
- ↑ Regulation of Genetic Tests
