Ethical questions need to be answered, including what genetic findings should be reported to patients.
New York geneticist Robert Marion, MD, envisions a future where whole-genome sequencing will be used to help prevent many medical conditions from developing.
Geneticists say this new era of medicine could occur within a decade, thanks to the complicated procedure being tested in a growing number of research settings across the country.
In whole-genome sequencing, geneticists use a patient’s blood sample or other source of genetic material to examine the 20,000 to 25,000 genes that make up an individual’s genome. By comparison, standard genetic testing used widely by health professionals today examines only individual genes, geneticists say. As a result, physicians often must order multiple tests to get needed genetic information.
Whole-genome sequencing will enable specialists to identify variations in a person’s genetic code that increase his or her genetic risk of developing a spectrum of conditions, including Alzheimer’s disease, cancer, diabetes and schizophrenia. The procedure also will reveal the cause of undiagnosed symptoms, an individual’s propensity for becoming dependant on nicotine, and the likely effect of medication on conditions such as asthma and cardiovascular disease.
Some geneticists estimate that within five years, as the procedure becomes more affordable, primary care physicians will begin sifting through patients’ whole-genome sequence results and creating preventive care plans for conditions the individual is at risk of developing. In 10 years, such sequencing could become a routine part of medical care performed on newborn babies and older patients.
An estimated 20,000 to 25,000 genes make up a person’s genome.
“Medicine will go from a field where we are reactive to one in which we can prevent symptoms and signs from ever occurring. That’s really a game-changer in medicine,” said Dr. Marion, chief of the division of genetics and child development in the Dept. of Pediatrics at the Children’s Hospital at Montefiore and the Albert Einstein College of Medicine in New York.
But these experts admit there are uncertainties and ethical concerns about whole-genome sequencing that need to be resolved before it becomes a standard procedure used by physicians for patients. Among the chief worries is what to do with the large number of variants in genes associated with human disease that can show up in a patient’s sequencing.
“The genome is so complex and some of our understanding of various mutations is so shaky that it’s hard to tell which information is meaningful and which isn’t,” said Robert C. Green, MD, MPH, associate professor of medicine in the Division of Genetics at Brigham and Women’s Hospital and Harvard Medical School in Boston.
There are no guidelines on which findings from whole-genome sequencing geneticists should report to physicians and which results should be passed on to patients, geneticists say. Also lacking is clear guidance on who should have access to the findings, such as a patient’s employer or relatives who could share some of the same genes.
“The ethics of this has to be worked out, but this is what usually happens in molecular genetics and technology in general,” Dr. Marion said. “This will alter the way we care for people.”
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