Is Finding Out Your Baby’s Genetics A New Responsibility of Parenting?
Hours after a baby is born, its heel is pricked with a lancet. Drops of the infant's blood are collected on a porous card, which is then mailed to a state laboratory. The dried blood spots are screened for around thirty conditions, including phenylketonuria (PKU), the metabolic disorder that kick-started this kind of newborn screening over 60 years ago. In the U.S., parents are not asked for permission to screen their child. Newborn screening programs are public health programs, and the assumption is that no good parent would refuse a screening test that could identify a serious yet treatable condition in their baby.
Learning as much as you can about your child's health might seem like a natural obligation of parenting. But it's an assumption that I think needs to be much more closely examined.
Today, with the introduction of genome sequencing into clinical medicine, some are asking whether newborn screening goes far enough. As the cost of sequencing falls, should parents take a more expansive look at their children's health, learning not just whether they have a rare but treatable childhood condition, but also whether they are at risk for untreatable conditions or for diseases that, if they occur at all, will strike only in adulthood? Should genome sequencing be a part of every newborn's care?
It's an idea that appeals to Anne Wojcicki, the founder and CEO of the direct-to-consumer genetic testing company 23andMe, who in a 2016 interview with The Guardian newspaper predicted that having newborns tested would soon be considered standard practice—"as critical as testing your cholesterol"—and a new responsibility of parenting. Wojcicki isn't the only one excited to see everyone's genes examined at birth. Francis Collins, director of the National Institutes of Health and perhaps the most prominent advocate of genomics in the United States, has written that he is "almost certain … that whole-genome sequencing will become part of new-born screening in the next few years." Whether that would happen through state-mandated screening programs, or as part of routine pediatric care—or perhaps as a direct-to-consumer service that parents purchase at birth or receive as a baby-shower gift—is not clear.
Learning as much as you can about your child's health might seem like a natural obligation of parenting. But it's an assumption that I think needs to be much more closely examined, both because the results that genome sequencing can return are more complex and more uncertain than one might expect, and because parents are not actually responsible for their child's lifelong health and well-being.
What is a parent supposed to do about such a risk except worry?
Existing newborn screening tests look for the presence of rare conditions that, if identified early in life, before the child shows any symptoms, can be effectively treated. Sequencing could identify many of these same kinds of conditions (and it might be a good tool if it could be targeted to those conditions alone), but it would also identify gene variants that confer an increased risk rather than a certainty of disease. Occasionally that increased risk will be significant. About 12 percent of women in the general population will develop breast cancer during their lives, while those who have a harmful BRCA1 or BRCA2 gene variant have around a 70 percent chance of developing the disease. But for many—perhaps most—conditions, the increased risk associated with a particular gene variant will be very small. Researchers have identified over 600 genes that appear to be associated with schizophrenia, for example, but any one of those confers only a tiny increase in risk for the disorder. What is a parent supposed to do about such a risk except worry?
Sequencing results are uncertain in other important ways as well. While we now have the ability to map the genome—to create a read-out of the pairs of genetic letters that make up a person's DNA—we are still learning what most of it means for a person's health and well-being. Researchers even have a name for gene variants they think might be associated with a disease or disorder, but for which they don't have enough evidence to be sure. They are called "variants of unknown (or uncertain) significance (VUS), and they pop up in most people's sequencing results. In cancer genetics, where much research has been done, about 1 in 5 gene variants are reclassified over time. Most are downgraded, which means that a good number of VUS are eventually designated benign.
While one parent might reasonably decide to learn about their child's risk for a condition about which nothing can be done medically, a different, yet still thoroughly reasonable, parent might prefer to remain ignorant so that they can enjoy the time before their child is afflicted.
Then there's the puzzle of what to do about results that show increased risk or even certainty for a condition that we have no idea how to prevent. Some genomics advocates argue that even if a result is not "medically actionable," it might have "personal utility" because it allows parents to plan for their child's future needs, to enroll them in research, or to connect with other families whose children carry the same genetic marker.
Finding a certain gene variant in one child might inform parents' decisions about whether to have another—and if they do, about whether to use reproductive technologies or prenatal testing to select against that variant in a future child. I have no doubt that for some parents these personal utility arguments are persuasive, but notice how far we've now strayed from the serious yet treatable conditions that motivated governments to set up newborn screening programs, and to mandate such testing for all.
Which brings me to the other problem with the call for sequencing newborn babies: the idea that even if it's not what the law requires, it's what good parents should do. That idea is very compelling when we're talking about sequencing results that show a serious threat to the child's health, especially when interventions are available to prevent or treat that condition. But as I have shown, many sequencing results are not of this type.
While one parent might reasonably decide to learn about their child's risk for a condition about which nothing can be done medically, a different, yet still thoroughly reasonable, parent might prefer to remain ignorant so that they can enjoy the time before their child is afflicted. This parent might decide that the worry—and the hypervigilence it could inspire in them—is not in their child's best interest, or indeed in their own. This parent might also think that it should be up to the child, when he or she is older, to decide whether to learn about his or her risk for adult-onset conditions, especially given that many adults at high familial risk for conditions like Alzheimer's or Huntington's disease choose never to be tested. This parent will value the child's future autonomy and right not to know more than they value the chance to prepare for a health risk that won't strike the child until 40 or 50 years in the future.
Parents are not obligated to learn about their children's risk for a condition that cannot be prevented, has a small risk of occurring, or that would appear only in adulthood.
Contemporary understandings of parenting are famously demanding. We are asked to do everything within our power to advance our children's health and well-being—to act always in our children's best interests. Against that backdrop, the need to sequence every newborn baby's genome might seem obvious. But we should be skeptical. Many sequencing results are complex and uncertain. Parents are not obligated to learn about their children's risk for a condition that cannot be prevented, has a small risk of occurring, or that would appear only in adulthood. To suggest otherwise is to stretch parental responsibilities beyond the realm of childhood and beyond factors that parents can control.
Couples Facing Fertility Treatments Should Beware of This
When Jane Stein and her husband used in-vitro fertilization in 2001 to become pregnant with twins, her fertility clinic recommended using a supplemental procedure called intracytoplasmic sperm injection (ICSI), known in fertility lingo as "ix-see."
'Add-on' fertility procedures are increasingly coming under scrutiny for having a high cost and low efficacy rate.
During IVF, an egg and sperm are placed in a petri dish together with the hope that a sperm will seek out and fertilize the egg. With ICSI, doctors inject sperm directly into the egg.
Stein, whose name has been changed to protect her privacy, agreed to try it. Her twins are now 16, but while 17 years have gone by since that procedure, the efficacy of ICSI is still unclear. In other words, while Stein succeeded in having children, it may not have been because of ICSI. It may simply have been because she did IVF.
The American Society for Reproductive Medicine has concluded, "There are no data to support the routine use of ICSI for non-male factor infertility." That is, ICSI can help couples have a baby when the issue is male infertility. But when it's not, the evidence of its effectiveness is lacking. And yet the procedure is being used more and more, even when male infertility is not the issue. Some 40 percent of fertility treatments in Europe, Asia and the Middle East now use ICSI, according to a world report released in 2016 by the International Committee for Monitoring Assisted Reproductive Technologies. In the Middle East, the figure is actually 100 percent, the report said.
ICSI is just one of many supplemental procedures, or 'add-ons,' increasingly coming under scrutiny for having a high cost and low efficacy rate. They cost anywhere from a couple of hundred dollars to several thousand – ICSI costs $2,000 to $3,000 -- hiking up the price of what is already a very costly endeavor. And many don't even work. Worse, some actually cause harm.
It's no surprise couples use them. They promise to increase the chance of conceiving. For patients who desperately want a child, money is no object. The Human Fertilization and Embryology Authority (HFEA) in the U.K. found that some 74 percent of patients who received fertility treatments over the last two years were given at least one type of add-on. Now, fertility associations in the U.S. and abroad have begun issuing guidance about which add-ons are worth the extra cost and which are not.
"Many IVF add-ons have little in the way of conclusive evidence supporting their role in successful IVF treatment," said Professor Geeta Nargund, medical director of CREATE Fertility and Lead Consultant for reproductive medicine at St George's Hospital, London.
The HFEA has actually rated these add-ons, indicating which procedures are effective and safe. Some treatments were rated 'red' because they were considered to have insufficient evidence to justify their use. These include assisted hatching, which uses acid or lasers to make a hole in the surrounding layer of proteins to help the embryo hatch; intrauterine culture, where a device is inserted into the womb to collect and incubate the embryo; and reproductive immunology, which suppresses the body's natural immunity so that it accepts the embryo.
"Fertility care is a highly competitive market. In a private system, offering add-ons may discern you from your neighboring clinic."
For some treatments, the HFEA found there is evidence that they don't just fail to work, but can even be harmful. These procedures include ICSI used when male infertility is not at issue, as well as a procedure called endometrial scratching, where the uterus is scratched, not unlike what would happen with a biopsy, to stimulate the local uterine immune system.
And then for some treatments, there is conflicting evidence, warranting further research. These include artificial egg activation by calcium ionophore, elective freezing in all cycles, embryo glue, time-lapse imaging and pre-implantation genetic testing for abnormal chromosomes on day 5.
"Currently, there is very little evidence to suggest that many of the add-ons could increase success rates," Nargund said. "Indeed, the HFEA's assessment of add-on treatments concluded that none of the add-ons could be given a 'green' rating, due to a lack of conclusive supporting research."
So why do fertility clinics offer them?
"Fertility care is a highly competitive market," said Professor Hans Evers, editor-in-chief of the journal Human Reproduction. "In a private system, offering add-ons may discern you from your neighboring clinic. The more competition, the more add-ons. Hopefully the more reputable institutions will only offer add-ons (for free) in the context of a randomized clinical trial."
The only way for infertile couples to know which work and which don't is the guidance released by professional organizations like the ASRM, and through government regulation in countries that have a public health care system.
The problem is, infertile couples will sometimes do anything to achieve a pregnancy.
"They will stand on their heads if this is advocated as helpful. Someone has to protect them," Evers said.
In the Netherlands, where Evers is based, the national health care system tries to make the best use of the limited resources it has, so it makes sure the procedures it's funding actually work, Evers said.
"We have calculated that to serve a population of 17 million, we need 13 IVF clinics, and we have 13," he said. "We as professionals discuss and try to agree on the value of newly proposed add-ons, and we will implement only those that are proven effective and safe."
Likewise, in the U.K., there's been a lot of squawking about speculative add-ons because the government, or National Health Service, pays for them. In the U.S., it's private insurers or patients' own cash.
"The [U.K.] government takes a very close look at what therapies they are offering and what the evidence is around offering the therapy," said Alan Penzias, who chairs the Practice Committee of the ASRM. It wants to make sure the treatments it is funding are at least worth the money.
ICSI is a case in point. Originally intended for male infertility, it's now being applied across the board because fertility clinics didn't want couples to pay $10,000 to $15,000 and wind up with no embryos.
"It is so disastrous to have no fertilization whatsoever, clinics started to make this bargain with their patients, saying, 'Well, listen, even though it's not indicated, what we would like to do is to take half of your eggs and do the ICSI procedure, and half we'll do conventional insemination just to make sure,'" he said. "It's a disaster if you have no embryos, and now you're out 10 to 12 thousand dollars, so for a small added fee, we can do the injection just to guard against that."
In the Netherlands, the national health care system tries to make the best use of its limited resources, so it makes sure the procedures it's funding actually work.
Clinics offer it where they see lower rates of fertilization, such as with older women or in cases where induced ovulation results in just two or three eggs instead of, say, 13. Unfortunately, ICSI may result in a higher fertilization rate, but it doesn't result in a higher live birth rate, according to a study last year in Human Reproduction, so couples wind up paying for a procedure that doesn't even result in a child.
Private insurers in the U.S. are keen to it. Penzia, who is also an associate professor of obstetrics, gynecology and reproductive biology at Harvard Medical School and works as a reproductive endocrinology and infertility specialist at Boston IVF, said Massachusetts requires that insurers cover infertility treatments. But when he submits claims for ICSI, for instance, insurers now want to see two sperm counts and proof that the man has seen a urologist.
"They want to make sure we're doing it for male factor (infertility)," he said. "That's not unreasonable, because the insurance company is taking the burden of this."
How exactly does your DNA make you who you are?
It's because of epigenetics that identical twins can actually look different and develop different diseases.
Just as software developers don't write apps out of ones and zeros, the interesting parts of the human genome aren't written merely in As, Ts, Cs and Gs. Yes, these are the fundamental letters that make up our DNA and encode the proteins that make our cells function, but the story doesn't end there.
Our cells possess amazing abilities, like eating invading bacteria or patching over a wound, and these abilities require the coordinated action of hundreds, if not thousands, of proteins. Epigenetics, the study of gene expression, examines how multiple genes work at once to make these biological processes happen.
It's because of epigenetics that identical twins – who possess identical DNA -- can actually look different and develop different diseases. Their environments may influence the expression of their genes in unique ways. For example, a research study in mice found that maternal exposure to a chemical called bisphenol A (BPA) resulted in drastic differences between genetically identical offspring. BPA exposure increased the likelihood that a certain gene was turned on, which led to the birth of yellow mice who were prone to obesity. Their genetically identical siblings who were not exposed to BPA were thinner and born with brown fur.
These three mice are genetically identical. Epigenetic differences, however, result in vastly different phenotypes.
(© 1994 Nature Publishing Group, Duhl, D.)
This famous mouse experiment is just one example of how epigenetics may transform medicine in the coming years. By studying the way genes are turned on and off, and maybe even making those changes ourselves, scientists are beginning to approach diseases like cancer in a completely new way.
With few exceptions, most of the 1 trillion cells that make up your body contain the same DNA instructions as all the others. How does each cell in your body know what it is and what it has to do? One of the answers appears to lie in epigenetic regulation. Just as everyone at a company may have access to all the same files on the office Dropbox, the accountants will put different files on their desktop than the lawyers do.
Our cells prioritize DNA sequences in the same way, even storing entire chromosomes that aren't needed along the wall of the nucleus, while keeping important pieces of DNA in the center, where it is most accessible to be read and used. One of the ways our cells prioritize certain DNA sequences is through methylation, a process that inactivates large regions of genes without editing the underlying "file" itself.
As we learn more about epigenetics, we gain more opportunities to develop therapeutics for a broad range of human conditions, from cancer to metabolic disorders. Though there have not been any clinical applications of epigenetics to immune or metabolic diseases yet, cancer is one of the leading areas, with promising initial successes.
One of the challenges of cancer treatments is that different patients may respond positively or negatively to the same treatment. With knowledge of epigenetics, however, doctors could conduct diagnostic tests to identify a patient's specific epigenetic profile and determine the best treatment for him or her. Already, commercial kits are available that help doctors screen glioma patients for an epigenetic biomarker called MGMT, because patients with this biomarker have shown high rates of success with certain kinds of treatments.
Other epigenetic advances go beyond personalized screening to treatments targeting the mechanism of disease. Some epigenetic drugs turn on genes that help suppress tumors, while others turn on genes that reveal the identity of tumor cells to the immune system, allowing it to attack cancerous cells.
Direct, targeted control of your epigenome could allow doctors to reprogram cancerous or aging cells.
The study of epigenetics has also been fundamental to the field of aging research. The older you get, the more methylation marks your DNA carries, and this has led to the distinction between biological aging, or the state of your cells, and chronological aging, or how old you actually are.
Just as our DNA can get miscopied and accumulate mutations, errors in DNA methylation can lead to so-called "epimutations". One of the big hypotheses in aging research today is that the accumulation of these random epimutations over time is responsible for what we perceive as aging.
Studies thus far have been correlative - looking at several hundred sites of epigenetic modifications in a person's cell, scientists can now roughly discern the age of that person. The next set of advances in the field will come from learning what these epigenetic changes individually do by themselves, and if certain methylations are correlated with cellular aging. General diagnostic terms like "aging" could be replaced with "abnormal methylation at these specific locations," which would also open the door to new therapeutic targets.
Direct, targeted control of your epigenome could allow doctors to reprogram cancerous or aging cells. While this type of genetic surgery is not feasible just yet, current research is bringing that possibility closer. The Cas9 protein of genome-editing CRISPR/Cas9 fame has been fused with epigenome modifying enzymes to target epigenetic modifications to specific DNA sequences.
A therapeutic of this type could theoretically undo a harmful DNA methylation, but would also be competing with the cell's native machinery responsible for controlling this process. One potential approach around this problem involves making beneficial synthetic changes to the epigenome that our cells do not have the capacity to undo.
Also fueling this frontier is a new approach to understanding disease itself. Scientists and doctors are now moving beyond the "one defective gene = one disease" paradigm. Because lots of diseases are caused by multiple genes going haywire, epigenetic therapies could hold the key to new types of treatments by targeting multiple defective genes at once.
Scientists are still discovering which epigenetic modifications are responsible for particular diseases, and engineers are building new tools for epigenome editing. Given the proliferation of work in these fields within the last 10 years, we may see epigenetic therapeutics emerging within the next couple of decades.