Genome sequencing is widely heralded as one of the most significant scientific breakthroughs of the 21st century, and despite its relative infancy it is already helping patients make more informed health care decisions, but its potential contribution to society holds greater promise still.
Indeed, as predictive technologies evolve and the global genomics database becomes ever more robust, researchers hope one day to not only treat inherited genetic disorders, such as cystic fibrosis, heart disease, and Alzheimer’s disease, more effectively, but to delay or prevent the onset of such diseases to begin with. A cure for cancer, of course, is the Holy Grail.
From a public health perspective, genomics also holds potential application in diagnosing infectious organisms like the bacteria that cause food poisoning (listeria), investigating virus outbreaks (Ebola) and developing vaccines to combat common pathogens, such as influenza, that could save lives.
“Advances in molecular technologies and bioinformatics have made it possible to examine genomes in much greater detail,” the CDC writes on its web site. “Now, falling cost and turnaround time are bringing high-throughput genetic sequencing within reach for use by clinical and public health investigators.”1
According to the National Human Genome Research Institute (NHGRI), genomics is the study of all of an organism’s genes (or, their genome), including how those genes interact with each other and with the environment. It includes the study of complex diseases such as asthma, cancer and heart disease, which are often caused by a combination of genetic and environmental factors, rather than by an individual gene.2
By comparison, NHGRI defines genetics as the study of specific genes and their roles in inheritance — or the manner in which specific traits or conditions are passed down from one generation to the next.
Genes are the basic units of heredity within human cells that determine inherited traits, including hair and eye color. It is estimated that humans have between 20,000 and 25,000 genes; each individual has two copies of each gene, one inherited from each parent, according to the National Library of Medicine.3
An organism’s genome contains a complete set of deoxyribonucleic acid (DNA), a chemical compound that contains genetic instructions. DNA molecules are comprised of two twisting, paired strands, and each is made of four chemical units, called nucleotide bases. The human genome contains roughly 3 billion of these base pairs, the National Human Genome Research Institute (NHGRI) reports.
Genome sequencing, then, involves determining the precise order of those DNA bases, according to Genome News Network, published by the J. Craig Venter Institute in Rockville, Maryland. The first complete human genome was successfully sequenced in 2003 by NHGRI, the Department of Energy, and their partners in the International Human Genome Sequencing Consortium via the Human Genome Project. It took 13 years and cost $2.7 billion.4 Today, with the advent of “next generation sequencing” technologies, however, individuals can have their individual genome sequenced for roughly $1,000 to $2,000 – in a matter of days.5
The data gleaned can be used by people to identify certain illnesses for which they may be genetically predisposed, allowing them to alter their lifestyle (exercise more, eat better, quit smoking) to potentially delay or prevent onset. The genomic data divulged may also motivate patients to seek treatment for symptoms sooner, which may lead to better outcomes.
Similarly, healthcare providers can potentially mine genomic data to facilitate an earlier diagnosis and more targeted intervention.
Steve Jobs, Apple founder and then-CEO, was among the first to sequence his DNA (and the specific tumor he was battling) in a bid to beat cancer before his death in 2011. The Silicon Valley visionary reportedly spent $100,000 to help doctors gain insight into which treatments might prove most effective. It did not result in the desired effect. Jobs died at age 50 from complications related to cancer, but according to his biographer, Walter Isaacson, Jobs maintained his belief in the untapped potential of genomics, famously stating: “I’m either going to be the first to be able to outrun a cancer like this, or I’m going to be the last to die from it.”
Pharmacogenomics, a newer field of medicine that uses an individual’s unique genome to determine whether a particular therapy, or dose of therapy, will be effective before it is administered, is yet another potential application of genomic medicine. Already, researchers at Stanford University in Stanford, California are developing a DNA-based test to determine the likelihood that a patient will reject a transplanted heart.6
To date, more than 2,000 genetic tests exist for human conditions, the National Institutes of Health reports, and many more are in the works. A team of scientists in Europe is using diagnostic sequencing to uncover candidate genes and mutations that cause severe intellectual disability.7
NHGRI also reports on its web site that DNA sequencing has recently been used to diagnose bacterial meningoencephalitis, which helped physicians quickly identify the most effective therapeutic agent for the patient, while whole genome sequencing technology has been used to correct a misdiagnosis of cerebral palsy in a pair of twins, leading to a new treatment regimen “to which both children are responding well.”8
Indeed, genomic sequencing has ushered in a new era of preemptive and personalized medicine, and it may one day help improve our quality of life, eradicate inherited disease and save lives.
While hopes remain high, however, NHGRI cautions the medical community (and the media) to manage expectations. Clinical trials for new products to move from the laboratory to the clinic – often span a decade or more to generate the data needed to win regulatory approval. And, of course, there are no guarantees. “It is important to be careful about raising expectations,” it states on its web site.
Most new drugs based on the completed genome are still at least 10 to 15 years from the market, although more than 350 biotech products – many based on genetic research – are currently in clinical trials, according to NIH.
There’s no denying that genome sequencing holds great promise for personal and public health, and could radically alter the way inherited disease gets diagnosed and treated. Just how fast or far it takes us, however, remains to be seen.