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Newborn screening programs are public health services aimed at ensuring that the close to 4 million infants born each year in the United States are screened for certain serious disorders at birth. These disorders, albeit rare, are detected in roughly 12,500 newborn babies every year.
Newborn screening isn’t new, although it has expanded and transformed over the decades. The first newborn screening test was developed in the 1960s to detect phenylketonuria (PKU).1 Since then, the number of conditions screened for has increased, with programs in every US state and territory. “Newborn screening is well established now, not experimental or newfangled,” Wendy Chung, MD, PhD, professor of pediatrics, Harvard Medical School, Boston, Massachusetts, told Neurology Reviews.
In newborn screening, blood drawn from the baby’s heel is applied to specialized filter paper, which is then subjected to several analytical methods, including tandem mass spectrometry and molecular analyses to detect biomarkers for the diseases.2 More recently, genomic sequencing is being piloted as part of consented research studies.3
Newborn screening includes not only biochemical and genetic testing, but also includes noninvasive screening for hearing loss or for critical congenital heart disease using pulse oximetry. And newborn screening goes beyond analysis of a single drop of blood. Rather, “it’s an entire system, with the goal of identifying babies with genetic disorders who otherwise have no obvious symptoms,” said Dr. Chung. Left undetected and untreated, these conditions can be associated with serious adverse outcomes and even death.
Dr. Chung described newborn screening as a “one of the most successful public health programs, supporting health equity by screening almost every US baby after birth and then bringing timely treatments when relevant even before the baby develops symptoms of a disorder.” In this way, newborn screening has “saved lives and decreased disease burdens.”
There are at present 38 core conditions that the Department of Health and Human Services (HHS) regards as the most critical to screen for and 26 secondary conditions associated with these core disorders. This is called the Recommended Uniform Screening Panel (RUSP). Guidance regarding the most appropriate application of newborn screening tests, technologies and standards are provided by the Advisory Committee on Heritable Disorders in Newborns and Children (ACHDNC).
Each state “independently determines which screening tests are performed and what follow-up is provided.”4 Information about which tests are provided by which states can be found on the “Report Card” of the National Organization for Rare Diseases (NORD).
Challenges in Expanding the Current Newborn Screening
One of the major drawbacks in the current system is that “we don’t screen for enough diseases,” according to Zhanzhi Hu, PhD, of the Department of Systems Biology and the Department of Biomedical Information, Columbia University, New York City. “There are over 10,000 rare genetic diseases, but we’re currently screening for fewer than 100,” he told Neurology Reviews. Although in the United States, there are about 700-800 drugs approved for genetic diseases, “we can’t identify patients with these diseases early enough for the ideal window when treatments are most effective.”
Moreover, it’s a “lengthy process” to add new diseases to RUSP. “New conditions are added at the pace of less than one per year, on average — even for the hundreds of diseases for which there are treatments,” he said. “If we keep going at the current pace, we won’t be able to screen for those diseases for another few hundred years.”
Speeding up the pace of including new diseases in newborn screening is challenging because “we have more diseases than we have development dollars for,” Dr. Hu said. “Big pharmaceutical companies are reluctant to invest in rare diseases because the population is so small and it’s hard and expensive to develop such drugs. So if we can identify patients first, there will be more interest in developing treatments down the road.”
On the other hand, for trials to take place, these babies have to be identified in a timely manner — which requires testing. “Right now, we have a deadlock,” Dr. Hu said. “To nominate a disease, you need an approved treatment. But to get a treatment developed, you need to identify patients suitable for a clinical trial. If you have to wait for the symptoms to show up, the damage has already manifested and is irreversible. Our chance is to recognize the disease before symptom onset and then start treatment. I would call this a ‘chicken-and-egg’ problem.”
Dr. Hu is passionate about expanding newborn screening, and he has a very personal reason. Two of his children have a rare genetic disease. “My younger son, now 13 years old, was diagnosed at a much earlier age than my older son, although he had very few symptoms at the time, because his older brother was known to have the disease. As a result of this, his outcome was much better.” By contrast, Dr. Hu’s oldest son — now age 16 — wasn’t diagnosed until he became symptomatic.
His quest led him to join forces with Dr. Chung in conducting the Genomic Uniform-screening Against Rare Disease in All Newborns (Guardian) study, which screens newborns for more than 450 genetic conditions not currently screened as part of the standard newborn screening. To date, the study — which focuses on babies born in New York City — has screened about 11,000 infants.
“To accumulate enough evidence requires screening at least 100,000 babies because one requirement for nominating a disease for national inclusion in RUSP is an ‘N of 1’ study — meaning, to identify at least one positive patient using the proposed screening method in a prospective study,” Dr. Hu explained. “Most are rare diseases with an incidence rate of around one in 100,000. So getting to that magic number of 100,000 participants should enable us to hit that ‘N of 1’ for most diseases.”
The most challenging part, according to Dr. Hu, is the requirement of a prospective study, which means that you have to conduct a large-scale study enrolling tens of thousands of families and babies. If done for individual diseases (as has been the case in the past), “this is a huge cost and very inefficient.”
In reality, he added, the true incidence of these diseases is unclear. “Incidence rates are based on historical data rather than prospective studies. We’ve already seen some diseases show up more frequently than previously recorded, while others have shown up less frequently.”
For example, in the 11,000 babies screened to date, at least three girls with Rett syndrome have been identified, which is “quite a bit higher” than what has previously been identified in the literature (ie, one in 10,000-12,000 births). “This is a highly unmet need for these families because if you can initiate early treatment — at age 1, or even younger — the outcome will be better.”
He noted that there is at least one clinical trial underway for treating Rett syndrome, which has yielded “promising” data.5 “We’re hoping that by screening for diseases like Rett and identifying patients early, this will go hand-in-hand with clinical drug development. It can speed both the approval of the treatment and the addition to the newborn screening list,” Dr. Hu stated.
Screening and Drug Development Working in Tandem
Sequencing technologies have advanced and become more sophisticated as well as less costly, so interest in expanding newborn screening through newborn genome sequencing has increased. In fact, many states currently have incorporated genetic testing into newborn screening for conditions without biochemical markers. Additionally, newborn genomic sequencing is also used for further testing in infants with abnormal biochemical screening results.6
Genomic sequencing “identifies nucleotide changes that are the underlying etiology of monogenic disorders.”6 Its use could potentially enable identification of over 500 genetic disorders for which an newborn screening assay is not currently available, said Dr. Hu.
“Molecular DNA analysis has been integrated into newborn testing either as a first- or second-tier test for several conditions, including cystic fibrosis, severe combined immunodeficiency, and spinal muscular atrophy (SMA),” Dr. Hu said.
Dr. Hu pointed to SMA to illustrate the power and potential of newborn screening working hand-in-hand with the development of new treatments. SMA is a neurodegenerative disorder caused by mutations in SMN1, which encodes survival motor neuron protein (SMN).7 Deficiencies in SMN results in loss of motor neurons with muscle weakness and, often, early death.7A pilot study, on which Dr. Chung was the senior author, used both biochemical and genetic testing of close to 4000 newborns and found an SMA carrier frequency of 1.5%. One newborn was identified who had a homozygous SMN1 gene deletion and two copies of SMN2, strongly suggesting the presence of a severe type 1 SMA phenotype.8
At age 15 days, the baby was treated with nusinersen, an injection administered into the fluid surrounding the spinal cord, and the first FDA-approved genetic treatment for SMA. At the time of study publication, the baby was 12 months old, “meeting all developmental milestones and free of any respiratory issues,” the authors report.
“Screening for SMA — which was added to the RUSP in 2018 — has dramatically transformed what used to be the most common genetic cause of death in children under the age of 2,” Dr. Chung said. “Now, a once-and-done IV infusion of genetic therapy right after screening has transformed everything, taking what used to be a lethal condition and allowing children to grow up healthy.”
Advocating for Inclusion of Diseases With No Current Treatment
At present, any condition included in the RUSP is required to have a treatment, which can be dietary, surgical/procedural, or an FDA-approved drug-based agent. Unfortunately, a wide range of neurodevelopmental diseases still have no known treatments. But lack of availability of treatment shouldn’t invalidate a disease from being included in the RUSP, because even if there is no specific treatment for the condition itself, early intervention can still be initiated to prevent some of the manifestations of the condition, said Dr. Hu.
“For example, most patients with these diseases will sooner or later undergo seizures,” Dr. Hu remarked. “We know that repeated seizures can cause brain damage. If we can diagnose the disease before the seizures start to take place, we can put preventive seizure control interventions in place, even if there is no direct ‘treatment’ for the condition itself.”
Early identification can lead to early intervention, which can have other benefits, Dr. Hu noted. “If we train the brain at a young age, when the brain is most receptive, even though a disease may be progressive and will worsen, those abilities acquired earlier will last longer and remain in place longer. When these skills are acquired later, they’re forgotten sooner. This isn’t a ‘cure,’ but it will help with functional improvement.”
Moreover, parents are “interested in knowing that their child has a condition, even if no treatment is currently available for that disorder, according to our research,” Dr. Chung said. “We found that the parents we interviewed endorsed the nonmedical utility of having access to information, even in the absence of a ‘cure,’ so they could prepare for medical issues that might arise down the road and make informed choices.”9
Nina Gold, MD, director of Prenatal Medical Genetics and associate director for Research for Massachusetts General Brigham Personalized Medicine, Boston, obtained similar findings in her own research, which is currently under review for publication. “We conducted focus groups and one-on-one interviews with parents from diverse racial and socioeconomic backgrounds. At least one parent said they didn’t want to compare their child to other children if their child might have a different developmental trajectory. They stressed that the information would be helpful, even if there was no immediate clinical utility.”
Additionally, there are an “increasing number of fetal therapies for rare disorders, so information about a genetic disease in an older child can be helpful for parents who may go on to have another pregnancy,” Dr. Gold noted.
Dr. Hu detailed several other reasons for including a wider range of disorders in the RUSP. Doing so helps families avoid a “stressful and expensive diagnostic odyssey and also provides equitable access to a diagnosis.” And if these patients are identified early, “we can connect the family with clinical trials already underway or connect them to an organization such as the Accelerating Medicines Partnership (AMP) Program Bespoke Gene Therapy Consortium (AMP BGTC). Bespoke “brings together partners from the public, private, and nonprofit sectors to foster development of gene therapies intended to treat rare genetic diseases, which affect populations too small for viable commercial development.”
Next Steps Following Screening
Rebecca Sponberg, NP, of the Children’s Hospital of Orange County, UC Irvine School of Medicine, California, is part of a broader multidisciplinary team that interfaces with parents whose newborns have screened positive for a genetic disorder. The team also includes a biochemical geneticist, a pediatric neurologist, a pediatric endocrinologist, a genetic counselor, and a social worker.
Different states and locations have different procedures for receiving test results, said Dr. Chung. In some, pediatricians are the ones who receive the results, and they are tasked with the responsibility of making sure the children can start getting appropriate care. In particular, these pediatricians are associated with centers of excellence that specialize in working with families around these conditions. Other facilities have multidisciplinary teams.
Ms. Sponberg gave an example of how the process unfolded with X-linked adrenoleukodystrophy, a rare genetic disorder that affects the white matter of the nervous system and the adrenal cortex.10 “This is the most common peroxisomal disorder, affecting one in 20,000 males,” she said. “There are several different forms of the disorder, but males are most at risk for having the cerebral form, which can lead to neurological regression and hasten death. But the regression does not appear until 4 to 12 years of age.”
A baby who screens positive on the initial newborn screening has repeat testing; and if it’s confirmed, the family meets the entire team to help them understand what the disorder is, what to expect, and how it’s monitored and managed. “Children have to be followed closely with a brain MRI every 6 months to detect brain abnormalities quickly,” Ms. Sponberg explained “And we do regular bloodwork to look for adrenocortical insufficiency.”
A child who shows concerning changes on the MRI or abnormal blood test findings is immediately seen by the relevant specialist. “So far, our center has had one patient who had MRI changes consistent with the cerebral form of the disease and the patient was immediately able to receive a bone marrow transplant,” she reported. “We don’t think this child’s condition would have been picked up so quickly or treatment initiated so rapidly if we hadn’t known about it through newborn screening.”
Educating and Involving Families
Part of the role of clinicians is to provide education regarding newborn screening to families, according to Ms. Sponberg. “In my role, I have to call parents to tell them their child screened positive for a genetic condition and that we need to proceed with confirmatory testing,” she said. “We let them know if there’s a high concern that this might be a true positive for the condition, and we offer them information so they know what to expect.”
Unfortunately, Ms. Sponberg said, in the absence of education, some families are skeptical. “When I call families directly, some think it’s a scam and it can be hard to earn their trust. We need to do a better job educating families, especially our pregnant individuals, that testing will occur and if anything is abnormal, they will receive a call.”
References
1. Levy HL. Robert Guthrie and the Trials and Tribulations of Newborn Screening. Int J Neonatal Screen. 2021 Jan 19;7(1):5. doi: 10.3390/ijns7010005.
2. Chace DH et al. Clinical Chemistry and Dried Blood Spots: Increasing Laboratory Utilization by Improved Understanding of Quantitative Challenges. Bioanalysis. 2014;6(21):2791-2794. doi: 10.4155/bio.14.237.
3. Gold NB et al. Perspectives of Rare Disease Experts on Newborn Genome Sequencing. JAMA Netw Open. 2023 May 1;6(5):e2312231. doi: 10.1001/jamanetworkopen.2023.12231.
4. Weismiller DG. Expanded Newborn Screening: Information and Resources for the Family Physician. Am Fam Physician. 2017 Jun 1;95(11):703-709. https://www.aafp.org/pubs/afp/issues/2017/0601/p703.html.
5. Neul JL et al. Trofinetide for the Treatment of Rett Syndrome: A Randomized Phase 3 Study. Nat Med. 2023 Jun;29(6):1468-1475. doi: 10.1038/s41591-023-02398-1.
6. Chen T et al. Genomic Sequencing as a First-Tier Screening Test and Outcomes of Newborn Screening. JAMA Netw Open. 2023 Sep 5;6(9):e2331162. doi: 10.1001/jamanetworkopen.2023.31162.
7. Mercuri E et al. Spinal Muscular Atrophy. Nat Rev Dis Primers. 2022 Aug 4;8(1):52. doi: 10.1038/s41572-022-00380-8.
8. Kraszewski JN et al. Pilot Study of Population-Based Newborn Screening for Spinal Muscular Atrophy in New York State. Genet Med. 2018 Jun;20(6):608-613. doi: 10.1038/gim.2017.152.
9. Timmins GT et al. Diverse Parental Perspectives of the Social and Educational Needs for Expanding Newborn Screening Through Genomic Sequencing. Public Health Genomics. 2022 Sep 15:1-8. doi: 10.1159/000526382.
10. Turk BR et al. X-linked Adrenoleukodystrophy: Pathology, Pathophysiology, Diagnostic Testing, Newborn Screening and Therapies. Int J Dev Neurosci. 2020 Feb;80(1):52-72. doi: 10.1002/jdn.10003.
Newborn screening programs are public health services aimed at ensuring that the close to 4 million infants born each year in the United States are screened for certain serious disorders at birth. These disorders, albeit rare, are detected in roughly 12,500 newborn babies every year.
Newborn screening isn’t new, although it has expanded and transformed over the decades. The first newborn screening test was developed in the 1960s to detect phenylketonuria (PKU).1 Since then, the number of conditions screened for has increased, with programs in every US state and territory. “Newborn screening is well established now, not experimental or newfangled,” Wendy Chung, MD, PhD, professor of pediatrics, Harvard Medical School, Boston, Massachusetts, told Neurology Reviews.
In newborn screening, blood drawn from the baby’s heel is applied to specialized filter paper, which is then subjected to several analytical methods, including tandem mass spectrometry and molecular analyses to detect biomarkers for the diseases.2 More recently, genomic sequencing is being piloted as part of consented research studies.3
Newborn screening includes not only biochemical and genetic testing, but also includes noninvasive screening for hearing loss or for critical congenital heart disease using pulse oximetry. And newborn screening goes beyond analysis of a single drop of blood. Rather, “it’s an entire system, with the goal of identifying babies with genetic disorders who otherwise have no obvious symptoms,” said Dr. Chung. Left undetected and untreated, these conditions can be associated with serious adverse outcomes and even death.
Dr. Chung described newborn screening as a “one of the most successful public health programs, supporting health equity by screening almost every US baby after birth and then bringing timely treatments when relevant even before the baby develops symptoms of a disorder.” In this way, newborn screening has “saved lives and decreased disease burdens.”
There are at present 38 core conditions that the Department of Health and Human Services (HHS) regards as the most critical to screen for and 26 secondary conditions associated with these core disorders. This is called the Recommended Uniform Screening Panel (RUSP). Guidance regarding the most appropriate application of newborn screening tests, technologies and standards are provided by the Advisory Committee on Heritable Disorders in Newborns and Children (ACHDNC).
Each state “independently determines which screening tests are performed and what follow-up is provided.”4 Information about which tests are provided by which states can be found on the “Report Card” of the National Organization for Rare Diseases (NORD).
Challenges in Expanding the Current Newborn Screening
One of the major drawbacks in the current system is that “we don’t screen for enough diseases,” according to Zhanzhi Hu, PhD, of the Department of Systems Biology and the Department of Biomedical Information, Columbia University, New York City. “There are over 10,000 rare genetic diseases, but we’re currently screening for fewer than 100,” he told Neurology Reviews. Although in the United States, there are about 700-800 drugs approved for genetic diseases, “we can’t identify patients with these diseases early enough for the ideal window when treatments are most effective.”
Moreover, it’s a “lengthy process” to add new diseases to RUSP. “New conditions are added at the pace of less than one per year, on average — even for the hundreds of diseases for which there are treatments,” he said. “If we keep going at the current pace, we won’t be able to screen for those diseases for another few hundred years.”
Speeding up the pace of including new diseases in newborn screening is challenging because “we have more diseases than we have development dollars for,” Dr. Hu said. “Big pharmaceutical companies are reluctant to invest in rare diseases because the population is so small and it’s hard and expensive to develop such drugs. So if we can identify patients first, there will be more interest in developing treatments down the road.”
On the other hand, for trials to take place, these babies have to be identified in a timely manner — which requires testing. “Right now, we have a deadlock,” Dr. Hu said. “To nominate a disease, you need an approved treatment. But to get a treatment developed, you need to identify patients suitable for a clinical trial. If you have to wait for the symptoms to show up, the damage has already manifested and is irreversible. Our chance is to recognize the disease before symptom onset and then start treatment. I would call this a ‘chicken-and-egg’ problem.”
Dr. Hu is passionate about expanding newborn screening, and he has a very personal reason. Two of his children have a rare genetic disease. “My younger son, now 13 years old, was diagnosed at a much earlier age than my older son, although he had very few symptoms at the time, because his older brother was known to have the disease. As a result of this, his outcome was much better.” By contrast, Dr. Hu’s oldest son — now age 16 — wasn’t diagnosed until he became symptomatic.
His quest led him to join forces with Dr. Chung in conducting the Genomic Uniform-screening Against Rare Disease in All Newborns (Guardian) study, which screens newborns for more than 450 genetic conditions not currently screened as part of the standard newborn screening. To date, the study — which focuses on babies born in New York City — has screened about 11,000 infants.
“To accumulate enough evidence requires screening at least 100,000 babies because one requirement for nominating a disease for national inclusion in RUSP is an ‘N of 1’ study — meaning, to identify at least one positive patient using the proposed screening method in a prospective study,” Dr. Hu explained. “Most are rare diseases with an incidence rate of around one in 100,000. So getting to that magic number of 100,000 participants should enable us to hit that ‘N of 1’ for most diseases.”
The most challenging part, according to Dr. Hu, is the requirement of a prospective study, which means that you have to conduct a large-scale study enrolling tens of thousands of families and babies. If done for individual diseases (as has been the case in the past), “this is a huge cost and very inefficient.”
In reality, he added, the true incidence of these diseases is unclear. “Incidence rates are based on historical data rather than prospective studies. We’ve already seen some diseases show up more frequently than previously recorded, while others have shown up less frequently.”
For example, in the 11,000 babies screened to date, at least three girls with Rett syndrome have been identified, which is “quite a bit higher” than what has previously been identified in the literature (ie, one in 10,000-12,000 births). “This is a highly unmet need for these families because if you can initiate early treatment — at age 1, or even younger — the outcome will be better.”
He noted that there is at least one clinical trial underway for treating Rett syndrome, which has yielded “promising” data.5 “We’re hoping that by screening for diseases like Rett and identifying patients early, this will go hand-in-hand with clinical drug development. It can speed both the approval of the treatment and the addition to the newborn screening list,” Dr. Hu stated.
Screening and Drug Development Working in Tandem
Sequencing technologies have advanced and become more sophisticated as well as less costly, so interest in expanding newborn screening through newborn genome sequencing has increased. In fact, many states currently have incorporated genetic testing into newborn screening for conditions without biochemical markers. Additionally, newborn genomic sequencing is also used for further testing in infants with abnormal biochemical screening results.6
Genomic sequencing “identifies nucleotide changes that are the underlying etiology of monogenic disorders.”6 Its use could potentially enable identification of over 500 genetic disorders for which an newborn screening assay is not currently available, said Dr. Hu.
“Molecular DNA analysis has been integrated into newborn testing either as a first- or second-tier test for several conditions, including cystic fibrosis, severe combined immunodeficiency, and spinal muscular atrophy (SMA),” Dr. Hu said.
Dr. Hu pointed to SMA to illustrate the power and potential of newborn screening working hand-in-hand with the development of new treatments. SMA is a neurodegenerative disorder caused by mutations in SMN1, which encodes survival motor neuron protein (SMN).7 Deficiencies in SMN results in loss of motor neurons with muscle weakness and, often, early death.7A pilot study, on which Dr. Chung was the senior author, used both biochemical and genetic testing of close to 4000 newborns and found an SMA carrier frequency of 1.5%. One newborn was identified who had a homozygous SMN1 gene deletion and two copies of SMN2, strongly suggesting the presence of a severe type 1 SMA phenotype.8
At age 15 days, the baby was treated with nusinersen, an injection administered into the fluid surrounding the spinal cord, and the first FDA-approved genetic treatment for SMA. At the time of study publication, the baby was 12 months old, “meeting all developmental milestones and free of any respiratory issues,” the authors report.
“Screening for SMA — which was added to the RUSP in 2018 — has dramatically transformed what used to be the most common genetic cause of death in children under the age of 2,” Dr. Chung said. “Now, a once-and-done IV infusion of genetic therapy right after screening has transformed everything, taking what used to be a lethal condition and allowing children to grow up healthy.”
Advocating for Inclusion of Diseases With No Current Treatment
At present, any condition included in the RUSP is required to have a treatment, which can be dietary, surgical/procedural, or an FDA-approved drug-based agent. Unfortunately, a wide range of neurodevelopmental diseases still have no known treatments. But lack of availability of treatment shouldn’t invalidate a disease from being included in the RUSP, because even if there is no specific treatment for the condition itself, early intervention can still be initiated to prevent some of the manifestations of the condition, said Dr. Hu.
“For example, most patients with these diseases will sooner or later undergo seizures,” Dr. Hu remarked. “We know that repeated seizures can cause brain damage. If we can diagnose the disease before the seizures start to take place, we can put preventive seizure control interventions in place, even if there is no direct ‘treatment’ for the condition itself.”
Early identification can lead to early intervention, which can have other benefits, Dr. Hu noted. “If we train the brain at a young age, when the brain is most receptive, even though a disease may be progressive and will worsen, those abilities acquired earlier will last longer and remain in place longer. When these skills are acquired later, they’re forgotten sooner. This isn’t a ‘cure,’ but it will help with functional improvement.”
Moreover, parents are “interested in knowing that their child has a condition, even if no treatment is currently available for that disorder, according to our research,” Dr. Chung said. “We found that the parents we interviewed endorsed the nonmedical utility of having access to information, even in the absence of a ‘cure,’ so they could prepare for medical issues that might arise down the road and make informed choices.”9
Nina Gold, MD, director of Prenatal Medical Genetics and associate director for Research for Massachusetts General Brigham Personalized Medicine, Boston, obtained similar findings in her own research, which is currently under review for publication. “We conducted focus groups and one-on-one interviews with parents from diverse racial and socioeconomic backgrounds. At least one parent said they didn’t want to compare their child to other children if their child might have a different developmental trajectory. They stressed that the information would be helpful, even if there was no immediate clinical utility.”
Additionally, there are an “increasing number of fetal therapies for rare disorders, so information about a genetic disease in an older child can be helpful for parents who may go on to have another pregnancy,” Dr. Gold noted.
Dr. Hu detailed several other reasons for including a wider range of disorders in the RUSP. Doing so helps families avoid a “stressful and expensive diagnostic odyssey and also provides equitable access to a diagnosis.” And if these patients are identified early, “we can connect the family with clinical trials already underway or connect them to an organization such as the Accelerating Medicines Partnership (AMP) Program Bespoke Gene Therapy Consortium (AMP BGTC). Bespoke “brings together partners from the public, private, and nonprofit sectors to foster development of gene therapies intended to treat rare genetic diseases, which affect populations too small for viable commercial development.”
Next Steps Following Screening
Rebecca Sponberg, NP, of the Children’s Hospital of Orange County, UC Irvine School of Medicine, California, is part of a broader multidisciplinary team that interfaces with parents whose newborns have screened positive for a genetic disorder. The team also includes a biochemical geneticist, a pediatric neurologist, a pediatric endocrinologist, a genetic counselor, and a social worker.
Different states and locations have different procedures for receiving test results, said Dr. Chung. In some, pediatricians are the ones who receive the results, and they are tasked with the responsibility of making sure the children can start getting appropriate care. In particular, these pediatricians are associated with centers of excellence that specialize in working with families around these conditions. Other facilities have multidisciplinary teams.
Ms. Sponberg gave an example of how the process unfolded with X-linked adrenoleukodystrophy, a rare genetic disorder that affects the white matter of the nervous system and the adrenal cortex.10 “This is the most common peroxisomal disorder, affecting one in 20,000 males,” she said. “There are several different forms of the disorder, but males are most at risk for having the cerebral form, which can lead to neurological regression and hasten death. But the regression does not appear until 4 to 12 years of age.”
A baby who screens positive on the initial newborn screening has repeat testing; and if it’s confirmed, the family meets the entire team to help them understand what the disorder is, what to expect, and how it’s monitored and managed. “Children have to be followed closely with a brain MRI every 6 months to detect brain abnormalities quickly,” Ms. Sponberg explained “And we do regular bloodwork to look for adrenocortical insufficiency.”
A child who shows concerning changes on the MRI or abnormal blood test findings is immediately seen by the relevant specialist. “So far, our center has had one patient who had MRI changes consistent with the cerebral form of the disease and the patient was immediately able to receive a bone marrow transplant,” she reported. “We don’t think this child’s condition would have been picked up so quickly or treatment initiated so rapidly if we hadn’t known about it through newborn screening.”
Educating and Involving Families
Part of the role of clinicians is to provide education regarding newborn screening to families, according to Ms. Sponberg. “In my role, I have to call parents to tell them their child screened positive for a genetic condition and that we need to proceed with confirmatory testing,” she said. “We let them know if there’s a high concern that this might be a true positive for the condition, and we offer them information so they know what to expect.”
Unfortunately, Ms. Sponberg said, in the absence of education, some families are skeptical. “When I call families directly, some think it’s a scam and it can be hard to earn their trust. We need to do a better job educating families, especially our pregnant individuals, that testing will occur and if anything is abnormal, they will receive a call.”
References
1. Levy HL. Robert Guthrie and the Trials and Tribulations of Newborn Screening. Int J Neonatal Screen. 2021 Jan 19;7(1):5. doi: 10.3390/ijns7010005.
2. Chace DH et al. Clinical Chemistry and Dried Blood Spots: Increasing Laboratory Utilization by Improved Understanding of Quantitative Challenges. Bioanalysis. 2014;6(21):2791-2794. doi: 10.4155/bio.14.237.
3. Gold NB et al. Perspectives of Rare Disease Experts on Newborn Genome Sequencing. JAMA Netw Open. 2023 May 1;6(5):e2312231. doi: 10.1001/jamanetworkopen.2023.12231.
4. Weismiller DG. Expanded Newborn Screening: Information and Resources for the Family Physician. Am Fam Physician. 2017 Jun 1;95(11):703-709. https://www.aafp.org/pubs/afp/issues/2017/0601/p703.html.
5. Neul JL et al. Trofinetide for the Treatment of Rett Syndrome: A Randomized Phase 3 Study. Nat Med. 2023 Jun;29(6):1468-1475. doi: 10.1038/s41591-023-02398-1.
6. Chen T et al. Genomic Sequencing as a First-Tier Screening Test and Outcomes of Newborn Screening. JAMA Netw Open. 2023 Sep 5;6(9):e2331162. doi: 10.1001/jamanetworkopen.2023.31162.
7. Mercuri E et al. Spinal Muscular Atrophy. Nat Rev Dis Primers. 2022 Aug 4;8(1):52. doi: 10.1038/s41572-022-00380-8.
8. Kraszewski JN et al. Pilot Study of Population-Based Newborn Screening for Spinal Muscular Atrophy in New York State. Genet Med. 2018 Jun;20(6):608-613. doi: 10.1038/gim.2017.152.
9. Timmins GT et al. Diverse Parental Perspectives of the Social and Educational Needs for Expanding Newborn Screening Through Genomic Sequencing. Public Health Genomics. 2022 Sep 15:1-8. doi: 10.1159/000526382.
10. Turk BR et al. X-linked Adrenoleukodystrophy: Pathology, Pathophysiology, Diagnostic Testing, Newborn Screening and Therapies. Int J Dev Neurosci. 2020 Feb;80(1):52-72. doi: 10.1002/jdn.10003.
Newborn screening programs are public health services aimed at ensuring that the close to 4 million infants born each year in the United States are screened for certain serious disorders at birth. These disorders, albeit rare, are detected in roughly 12,500 newborn babies every year.
Newborn screening isn’t new, although it has expanded and transformed over the decades. The first newborn screening test was developed in the 1960s to detect phenylketonuria (PKU).1 Since then, the number of conditions screened for has increased, with programs in every US state and territory. “Newborn screening is well established now, not experimental or newfangled,” Wendy Chung, MD, PhD, professor of pediatrics, Harvard Medical School, Boston, Massachusetts, told Neurology Reviews.
In newborn screening, blood drawn from the baby’s heel is applied to specialized filter paper, which is then subjected to several analytical methods, including tandem mass spectrometry and molecular analyses to detect biomarkers for the diseases.2 More recently, genomic sequencing is being piloted as part of consented research studies.3
Newborn screening includes not only biochemical and genetic testing, but also includes noninvasive screening for hearing loss or for critical congenital heart disease using pulse oximetry. And newborn screening goes beyond analysis of a single drop of blood. Rather, “it’s an entire system, with the goal of identifying babies with genetic disorders who otherwise have no obvious symptoms,” said Dr. Chung. Left undetected and untreated, these conditions can be associated with serious adverse outcomes and even death.
Dr. Chung described newborn screening as a “one of the most successful public health programs, supporting health equity by screening almost every US baby after birth and then bringing timely treatments when relevant even before the baby develops symptoms of a disorder.” In this way, newborn screening has “saved lives and decreased disease burdens.”
There are at present 38 core conditions that the Department of Health and Human Services (HHS) regards as the most critical to screen for and 26 secondary conditions associated with these core disorders. This is called the Recommended Uniform Screening Panel (RUSP). Guidance regarding the most appropriate application of newborn screening tests, technologies and standards are provided by the Advisory Committee on Heritable Disorders in Newborns and Children (ACHDNC).
Each state “independently determines which screening tests are performed and what follow-up is provided.”4 Information about which tests are provided by which states can be found on the “Report Card” of the National Organization for Rare Diseases (NORD).
Challenges in Expanding the Current Newborn Screening
One of the major drawbacks in the current system is that “we don’t screen for enough diseases,” according to Zhanzhi Hu, PhD, of the Department of Systems Biology and the Department of Biomedical Information, Columbia University, New York City. “There are over 10,000 rare genetic diseases, but we’re currently screening for fewer than 100,” he told Neurology Reviews. Although in the United States, there are about 700-800 drugs approved for genetic diseases, “we can’t identify patients with these diseases early enough for the ideal window when treatments are most effective.”
Moreover, it’s a “lengthy process” to add new diseases to RUSP. “New conditions are added at the pace of less than one per year, on average — even for the hundreds of diseases for which there are treatments,” he said. “If we keep going at the current pace, we won’t be able to screen for those diseases for another few hundred years.”
Speeding up the pace of including new diseases in newborn screening is challenging because “we have more diseases than we have development dollars for,” Dr. Hu said. “Big pharmaceutical companies are reluctant to invest in rare diseases because the population is so small and it’s hard and expensive to develop such drugs. So if we can identify patients first, there will be more interest in developing treatments down the road.”
On the other hand, for trials to take place, these babies have to be identified in a timely manner — which requires testing. “Right now, we have a deadlock,” Dr. Hu said. “To nominate a disease, you need an approved treatment. But to get a treatment developed, you need to identify patients suitable for a clinical trial. If you have to wait for the symptoms to show up, the damage has already manifested and is irreversible. Our chance is to recognize the disease before symptom onset and then start treatment. I would call this a ‘chicken-and-egg’ problem.”
Dr. Hu is passionate about expanding newborn screening, and he has a very personal reason. Two of his children have a rare genetic disease. “My younger son, now 13 years old, was diagnosed at a much earlier age than my older son, although he had very few symptoms at the time, because his older brother was known to have the disease. As a result of this, his outcome was much better.” By contrast, Dr. Hu’s oldest son — now age 16 — wasn’t diagnosed until he became symptomatic.
His quest led him to join forces with Dr. Chung in conducting the Genomic Uniform-screening Against Rare Disease in All Newborns (Guardian) study, which screens newborns for more than 450 genetic conditions not currently screened as part of the standard newborn screening. To date, the study — which focuses on babies born in New York City — has screened about 11,000 infants.
“To accumulate enough evidence requires screening at least 100,000 babies because one requirement for nominating a disease for national inclusion in RUSP is an ‘N of 1’ study — meaning, to identify at least one positive patient using the proposed screening method in a prospective study,” Dr. Hu explained. “Most are rare diseases with an incidence rate of around one in 100,000. So getting to that magic number of 100,000 participants should enable us to hit that ‘N of 1’ for most diseases.”
The most challenging part, according to Dr. Hu, is the requirement of a prospective study, which means that you have to conduct a large-scale study enrolling tens of thousands of families and babies. If done for individual diseases (as has been the case in the past), “this is a huge cost and very inefficient.”
In reality, he added, the true incidence of these diseases is unclear. “Incidence rates are based on historical data rather than prospective studies. We’ve already seen some diseases show up more frequently than previously recorded, while others have shown up less frequently.”
For example, in the 11,000 babies screened to date, at least three girls with Rett syndrome have been identified, which is “quite a bit higher” than what has previously been identified in the literature (ie, one in 10,000-12,000 births). “This is a highly unmet need for these families because if you can initiate early treatment — at age 1, or even younger — the outcome will be better.”
He noted that there is at least one clinical trial underway for treating Rett syndrome, which has yielded “promising” data.5 “We’re hoping that by screening for diseases like Rett and identifying patients early, this will go hand-in-hand with clinical drug development. It can speed both the approval of the treatment and the addition to the newborn screening list,” Dr. Hu stated.
Screening and Drug Development Working in Tandem
Sequencing technologies have advanced and become more sophisticated as well as less costly, so interest in expanding newborn screening through newborn genome sequencing has increased. In fact, many states currently have incorporated genetic testing into newborn screening for conditions without biochemical markers. Additionally, newborn genomic sequencing is also used for further testing in infants with abnormal biochemical screening results.6
Genomic sequencing “identifies nucleotide changes that are the underlying etiology of monogenic disorders.”6 Its use could potentially enable identification of over 500 genetic disorders for which an newborn screening assay is not currently available, said Dr. Hu.
“Molecular DNA analysis has been integrated into newborn testing either as a first- or second-tier test for several conditions, including cystic fibrosis, severe combined immunodeficiency, and spinal muscular atrophy (SMA),” Dr. Hu said.
Dr. Hu pointed to SMA to illustrate the power and potential of newborn screening working hand-in-hand with the development of new treatments. SMA is a neurodegenerative disorder caused by mutations in SMN1, which encodes survival motor neuron protein (SMN).7 Deficiencies in SMN results in loss of motor neurons with muscle weakness and, often, early death.7A pilot study, on which Dr. Chung was the senior author, used both biochemical and genetic testing of close to 4000 newborns and found an SMA carrier frequency of 1.5%. One newborn was identified who had a homozygous SMN1 gene deletion and two copies of SMN2, strongly suggesting the presence of a severe type 1 SMA phenotype.8
At age 15 days, the baby was treated with nusinersen, an injection administered into the fluid surrounding the spinal cord, and the first FDA-approved genetic treatment for SMA. At the time of study publication, the baby was 12 months old, “meeting all developmental milestones and free of any respiratory issues,” the authors report.
“Screening for SMA — which was added to the RUSP in 2018 — has dramatically transformed what used to be the most common genetic cause of death in children under the age of 2,” Dr. Chung said. “Now, a once-and-done IV infusion of genetic therapy right after screening has transformed everything, taking what used to be a lethal condition and allowing children to grow up healthy.”
Advocating for Inclusion of Diseases With No Current Treatment
At present, any condition included in the RUSP is required to have a treatment, which can be dietary, surgical/procedural, or an FDA-approved drug-based agent. Unfortunately, a wide range of neurodevelopmental diseases still have no known treatments. But lack of availability of treatment shouldn’t invalidate a disease from being included in the RUSP, because even if there is no specific treatment for the condition itself, early intervention can still be initiated to prevent some of the manifestations of the condition, said Dr. Hu.
“For example, most patients with these diseases will sooner or later undergo seizures,” Dr. Hu remarked. “We know that repeated seizures can cause brain damage. If we can diagnose the disease before the seizures start to take place, we can put preventive seizure control interventions in place, even if there is no direct ‘treatment’ for the condition itself.”
Early identification can lead to early intervention, which can have other benefits, Dr. Hu noted. “If we train the brain at a young age, when the brain is most receptive, even though a disease may be progressive and will worsen, those abilities acquired earlier will last longer and remain in place longer. When these skills are acquired later, they’re forgotten sooner. This isn’t a ‘cure,’ but it will help with functional improvement.”
Moreover, parents are “interested in knowing that their child has a condition, even if no treatment is currently available for that disorder, according to our research,” Dr. Chung said. “We found that the parents we interviewed endorsed the nonmedical utility of having access to information, even in the absence of a ‘cure,’ so they could prepare for medical issues that might arise down the road and make informed choices.”9
Nina Gold, MD, director of Prenatal Medical Genetics and associate director for Research for Massachusetts General Brigham Personalized Medicine, Boston, obtained similar findings in her own research, which is currently under review for publication. “We conducted focus groups and one-on-one interviews with parents from diverse racial and socioeconomic backgrounds. At least one parent said they didn’t want to compare their child to other children if their child might have a different developmental trajectory. They stressed that the information would be helpful, even if there was no immediate clinical utility.”
Additionally, there are an “increasing number of fetal therapies for rare disorders, so information about a genetic disease in an older child can be helpful for parents who may go on to have another pregnancy,” Dr. Gold noted.
Dr. Hu detailed several other reasons for including a wider range of disorders in the RUSP. Doing so helps families avoid a “stressful and expensive diagnostic odyssey and also provides equitable access to a diagnosis.” And if these patients are identified early, “we can connect the family with clinical trials already underway or connect them to an organization such as the Accelerating Medicines Partnership (AMP) Program Bespoke Gene Therapy Consortium (AMP BGTC). Bespoke “brings together partners from the public, private, and nonprofit sectors to foster development of gene therapies intended to treat rare genetic diseases, which affect populations too small for viable commercial development.”
Next Steps Following Screening
Rebecca Sponberg, NP, of the Children’s Hospital of Orange County, UC Irvine School of Medicine, California, is part of a broader multidisciplinary team that interfaces with parents whose newborns have screened positive for a genetic disorder. The team also includes a biochemical geneticist, a pediatric neurologist, a pediatric endocrinologist, a genetic counselor, and a social worker.
Different states and locations have different procedures for receiving test results, said Dr. Chung. In some, pediatricians are the ones who receive the results, and they are tasked with the responsibility of making sure the children can start getting appropriate care. In particular, these pediatricians are associated with centers of excellence that specialize in working with families around these conditions. Other facilities have multidisciplinary teams.
Ms. Sponberg gave an example of how the process unfolded with X-linked adrenoleukodystrophy, a rare genetic disorder that affects the white matter of the nervous system and the adrenal cortex.10 “This is the most common peroxisomal disorder, affecting one in 20,000 males,” she said. “There are several different forms of the disorder, but males are most at risk for having the cerebral form, which can lead to neurological regression and hasten death. But the regression does not appear until 4 to 12 years of age.”
A baby who screens positive on the initial newborn screening has repeat testing; and if it’s confirmed, the family meets the entire team to help them understand what the disorder is, what to expect, and how it’s monitored and managed. “Children have to be followed closely with a brain MRI every 6 months to detect brain abnormalities quickly,” Ms. Sponberg explained “And we do regular bloodwork to look for adrenocortical insufficiency.”
A child who shows concerning changes on the MRI or abnormal blood test findings is immediately seen by the relevant specialist. “So far, our center has had one patient who had MRI changes consistent with the cerebral form of the disease and the patient was immediately able to receive a bone marrow transplant,” she reported. “We don’t think this child’s condition would have been picked up so quickly or treatment initiated so rapidly if we hadn’t known about it through newborn screening.”
Educating and Involving Families
Part of the role of clinicians is to provide education regarding newborn screening to families, according to Ms. Sponberg. “In my role, I have to call parents to tell them their child screened positive for a genetic condition and that we need to proceed with confirmatory testing,” she said. “We let them know if there’s a high concern that this might be a true positive for the condition, and we offer them information so they know what to expect.”
Unfortunately, Ms. Sponberg said, in the absence of education, some families are skeptical. “When I call families directly, some think it’s a scam and it can be hard to earn their trust. We need to do a better job educating families, especially our pregnant individuals, that testing will occur and if anything is abnormal, they will receive a call.”
References
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2. Chace DH et al. Clinical Chemistry and Dried Blood Spots: Increasing Laboratory Utilization by Improved Understanding of Quantitative Challenges. Bioanalysis. 2014;6(21):2791-2794. doi: 10.4155/bio.14.237.
3. Gold NB et al. Perspectives of Rare Disease Experts on Newborn Genome Sequencing. JAMA Netw Open. 2023 May 1;6(5):e2312231. doi: 10.1001/jamanetworkopen.2023.12231.
4. Weismiller DG. Expanded Newborn Screening: Information and Resources for the Family Physician. Am Fam Physician. 2017 Jun 1;95(11):703-709. https://www.aafp.org/pubs/afp/issues/2017/0601/p703.html.
5. Neul JL et al. Trofinetide for the Treatment of Rett Syndrome: A Randomized Phase 3 Study. Nat Med. 2023 Jun;29(6):1468-1475. doi: 10.1038/s41591-023-02398-1.
6. Chen T et al. Genomic Sequencing as a First-Tier Screening Test and Outcomes of Newborn Screening. JAMA Netw Open. 2023 Sep 5;6(9):e2331162. doi: 10.1001/jamanetworkopen.2023.31162.
7. Mercuri E et al. Spinal Muscular Atrophy. Nat Rev Dis Primers. 2022 Aug 4;8(1):52. doi: 10.1038/s41572-022-00380-8.
8. Kraszewski JN et al. Pilot Study of Population-Based Newborn Screening for Spinal Muscular Atrophy in New York State. Genet Med. 2018 Jun;20(6):608-613. doi: 10.1038/gim.2017.152.
9. Timmins GT et al. Diverse Parental Perspectives of the Social and Educational Needs for Expanding Newborn Screening Through Genomic Sequencing. Public Health Genomics. 2022 Sep 15:1-8. doi: 10.1159/000526382.
10. Turk BR et al. X-linked Adrenoleukodystrophy: Pathology, Pathophysiology, Diagnostic Testing, Newborn Screening and Therapies. Int J Dev Neurosci. 2020 Feb;80(1):52-72. doi: 10.1002/jdn.10003.