Your genes tell a story of health and disease risk — and they tell that story from the day you are born.
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With that in mind, interest in genomic sequencing for newborns is rising. In 2013, the National Institutes of Health awarded $25 million to four major research projects examining the practice. More recently, one of the research teams published results from a study focusing on how genome sequencing affects the diagnosis of neurodevelopmental disorders. Studies have included a small number of patients so far, but the research is ongoing. The goals of each project vary. But ultimately, they center around analyzing the value of genomic sequencing of newborns — and assessing how widespread it should be.
In the meantime, parents have questions. To help provide clarity, I reached out to pediatric genomics expert Tim Moss, MD, PhD. Below, we answer a few common questions together.
Can you describe the different types of sequencing?
Dr. Moss: I think that’s one of the things that confuses people the most. There are a couple of different types. Whole exome sequencing—which we use commonly now—looks at only 1 to 2 percent of our bodies’ genome. It looks at the gene regions that make proteins we know are associated with disease. We use it to identify the mutations involved in a disease, and then we can develop a medical plan to act accordingly.
Whole genome sequencing is much broader. It looks at everything, up to 98 percent or 99 percent of your genome, including all the parts that don’t go into making a protein. It is not widespread in clinical use. Part of the reason is that it reveals many things we don’t yet understand. Unlike whole exome sequencing, we can’t always act on the results.
“Many parents wonder, ‘Do I want to know my child has a BRCA mutation that won’t become a risk for cancer for at least 25 or 30 years?’”
Charis Eng, MD, PhD
Founding Chairwoman of the Genomic Medicine Institute
When is exome sequencing used in newborns currently?
Dr. Moss: We use it when there are serious signs of illness or development disorders. Congenital issues and heart defects would be two examples. Many times, we order sequencing when other testing hasn’t revealed an answer, often when a child is very ill.
Dr. Eng: It is a diagnostic tool. We use it when we think there is a high probability of a genetic mutation — a mutation that may explain an illness or disorder.
What type of sequencing are researchers using?
Dr. Eng: We use both exome and genome sequencing for research. That is why it’s not so easy to understand all the variants (hundreds to thousands) we identify. However, one research goal—funded by the NIH grants—would be to determine how useful whole genome sequencing for newborns would be. Are there cases where it’s more valuable than more targeted screening?
Dr. Moss: When you start screening for everything—especially at an early age—that brings up questions. For example, do parents want or need information on genetic mutations when we don’t have medical answers for them? That’s one thing research teams are examining closely. In fact, they are including biomedical ethicists to ask those types of questions.
Dr. Eng: Many parents wonder, ‘Do I want to know my child has a BRCA mutation that won’t become a risk for cancer for at least 25 or 30 years?’ That’s just one example. It’s a good reason any genetic screening should be done with genetic counseling both before the test and after the results return. A genetic counselor helps patients and parents get the proper information, explanations and context.
What else should parents know about genomic sequencing?
Dr. Moss: It’s a complicated field. There aren’t always yes or no answers to hard questions. For example, the biggest health concerns—such as most cancer types or type 2 diabetes—won’t be answered by genomic sequencing. Targeted sequencing focuses on classic hereditary conditions, whether that is Marfan syndrome, Cowden syndrome or something else.
It is also highly personal. Parents have their own preferences on what they want to know and what they don’t want to know. They may want to know only about diseases for which doctors can craft a management plan for a child, like Marfan. They may not want to know about the risk of something like Alzheimer’s, where the future is less clear.
Dr. Eng: That’s a really important note. Any system of increased genetic testing would need to include opt-in and opt-out options. We want genetic information to empower patients—or their parents, in the case of newborns. But that means the choice must start with them, guided by genetic counselors.
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