Personal genome sequencing assesses the status of all of your genes at one time, just as if the Human Genome Project were conducted specifically on you.
The completion of the Human Genome Project was a great advance for medical research, providing us with part of the blueprint that makes us human. However, the DNA sequence produced by the Human Genome Project is not identical to yours; virtually every individual on the planet carries a unique set of variations in their DNA sequence, affecting their outward appearance, their behavior, and from a medical standpoint, their susceptibility to disease.
An analysis of your entire genome would not only assess genes that are implicated in disease, but could also reveal information about your physical traits, your behavior, and even your ancestry. In addition, this assessment would include portions of the genome that are not yet well understood, including genes whose function is not yet known. As its stands today, only the information from the parts of your genome that are well understood might benefit your present health care choices. However, as more and more people are sequenced, scientists will be provided with a larger set of data from which to learn about the poorly understood regions of the genome and their functions, including relationships to diseases. This is one potential benefit to health care consumers in the future (see Genotype and phenotype). In some ways, widespread personal genome sequencing may blur the line between medical practice and biomedical research. (Importantly, your genome is dynamic and only part of the story. Click here to learn more.)
An ever-growing list of genetic tests are available to look for known genetic mutations that are associated with specific diseases. Genetic tests usually characterize only one gene (or just specific parts of one gene), and the availability of such genetic tests depends on the ability of scientists to link well-characterized diseases to particular genes. For conditions with specific genetic causes, such as Huntington’s disease or cystic fibrosis, these tests have proven to be relatively straightforward. In contrast, progress has been more challenging with respect to predicting a person’s risk for complex and multifactorial diseases, such as diabetes and heart disease.
Sequencing personal genomes
The technology that made the Human Genome Project possible is plummeting in cost, and as a result, genetic analysis is increasingly available to a broader population. The first sequence of the human genome was achieved with hundreds of sequencing machines working for years. Now a single machine can sequence a full human genome in a matter of days. (Note, the analysis takes much longer than the actual process of sequencing.) In 2016, the cost of sequencing a human genome is roughly $1,000 (US), and companies continue to compete to reduce the cost. Sequencing a person’s genome has already found clinical applications, particularly in the diagnosis of rare childhood conditions and informing cancer therapeutics.
Vision for the future?
To make the sequencing technology more accessible, there has also been a push to make sequencing machines smaller and more affordable. Some companies are developing sequencing machines that are the size of a loaf of bread or even a bar of soap (see MinION photo for one example). In the coming years, perhaps reading human genomes might become a routine tool for preventative medicine as well and might be carried out in your doctor’s office.
Ultimately, the application of genomic information could enhance our ability to make informed and appropriate decisions regarding health care, including, for example, the treatment of specific diseases or predispositions and the choice of drugs and drug dosage. At the same time, the questions it raises, and the possible unforeseen medical and social consequences, are yet to be fully explored. This advent of “personal genetics” will bring novel challenges and extensive questions on the ethical, legal and social issues (ELSI) that we, as a society and as individuals, need to address.