As a clinician treating autism spectrum disorders (ASD) and related developmental disabilities, I find the advent of relatively inexpensive whole-genome testing tantalizing because we know it will provide a deeper look into the condition of our patients. But the coming wave of testing also troubles me.
Technological advances have already provided us with an amazingly helpful and sensitive test known as microarray comparative genomic hybridization, or “array CGH” for short. Array CGH permits us to identify copy-number variants—minute duplications and deletions—in the DNA of patients in whom, previously, no apparent genetic abnormality could be identified. The array has been especially helpful in evaluating kids with ASD: using it, we have found that about 20 percent of these patients have a deletion or duplication of genetic material. When a copy-number variant is present in a child (and neither parent is found to carry it), we can counsel the parents that their chances of having a second child with autism is no greater than the risk in the general population.
Although array CGH testing has been a godsend for many families, we are desperate to provide the majority of patients and families with a test that will offer them a better understanding of the cause of their ASD and potential treatments that are more effective. This is why we are breathlessly awaiting the coming age of the “$1,000 genome.”
The technology to perform whole-genome sequencing (WGS) and whole exome sequencing (WES) has existed for a decade, though the prohibitively high cost has prevented us from being able to offer this testing in the clinic. But rapid advances in data analysis mean the day is approaching when the cost will drop to $1,000 or less, and we will be able to perform this test for patients with ASD as well as for those with a wide variety of other conditions whose etiology is currently not known.
It has been predicted that WGS will routinely be used in newborn screening, permitting us to identify all disease-causing changes in the DNA (polymorphisms and mutations) in newborn infants, identifying kids who are at risk for cancers, hypertension, coronary artery disease, schizophrenia and virtually every other chronic medical condition before these conditions manifest themselves.
That leads us to the million-dollar question: What will we do with this information?
The $1,000 genome will be wonderful, but it will also be terrifying. On the one hand, medicine will change from a field in which we wait for people to develop symptoms and signs of disease to one in which, knowing that individuals are susceptible to develop that disease, we’ll be able to provide changes to their environment and lifestyle that may prevent them from ever developing those symptoms and signs.
On the other hand, widespread, inexpensive genetic testing will present thorny ethical challenges. What if we know that an infant carries a mutation that will make her highly susceptible to developing breast cancer at age 30 or 40? Should we tell her parents? Who should have access to the information? The family? The child’s physicians? The family’s insurance company? The child’s eventual employer?
These and myriad other questions are raised by the new genetic screening tests. As is always the case with medical technology, the advances occur far ahead of the ethical, legal and social responses to those advances.
With the $1,000 genome now just a couple of years away from becoming reality, it is essential that we work hard to consider the ramifications of sophisticated testing whose results some will deem “all-knowing” but few doctors or patients will be fully able to explain or accept.