Residency · Residency · Medical Genetics Genomics

Genome-Informed Newborn Screening: Promise and Controversy

Introduction

Newborn screening (NBS) is among the most successful public health programs in medicine, identifying treatable conditions in presymptomatic neonates. The potential to supplement or replace traditional biochemical NBS with genomic sequencing promises to expand the number of detectable conditions dramatically but raises profound questions about scope, consent, equity, and the balance between benefit and harm.

Current Newborn Screening

Established Framework

Newborn screening began in the 1960s with Robert Guthrie's test for phenylketonuria (PKU). The Recommended Uniform Screening Panel (RUSP) currently includes 37 core conditions and 26 secondary conditions as of 2024. The program primarily uses tandem mass spectrometry (MS/MS) for metabolic disorders, immunoassays for endocrine disorders, and other targeted assays. Additional screening includes hearing assessment, pulse oximetry for critical congenital heart disease, and point-of-care tests for specific conditions. NBS operates under a public health mandate in most US states, with parental consent not required in most jurisdictions, though opt-out is allowed in some states.

Wilson and Jungner Criteria (1968)

Traditional screening criteria upon which NBS programs are built stipulate that the condition should be an important health problem, an accepted treatment should be available, facilities for diagnosis and treatment should be available, a recognizable latent or early symptomatic stage should exist, a suitable screening test should be available, the test should be acceptable to the population, the natural history should be adequately understood, there should be an agreed-upon policy on whom to treat, the cost should be economically balanced against benefit, and case-finding should be a continuing process.

Genomic Newborn Screening: The Concept

Approaches

Several models exist for incorporating genomics into newborn screening. Supplementary genomic NBS adds sequencing to existing biochemical NBS to detect additional conditions or improve specificity. Replacement genomic NBS uses sequencing as the primary screening method replacing biochemical assays. Targeted gene panels sequence a defined set of genes associated with actionable childhood conditions. Whole exome or genome sequencing represents the broadest approach with maximum detection capability but also maximum complexity.

Potential Advantages

Genomic NBS could detect conditions not identifiable by biochemical screening, such as genetic hearing loss, immune deficiencies, and early-onset epilepsies. It could improve specificity, with genomic results reducing false positives that cause parental anxiety and unnecessary follow-up. A single platform could screen across hundreds of conditions simultaneously. Early identification would enable presymptomatic intervention for a broader range of conditions. Pharmacogenomic information would be available from birth for lifelong use.

Current Research Programs

BabySeq at Brigham and Women's Hospital/Harvard was a randomized trial of whole genome sequencing in healthy and NICU newborns that found actionable results in approximately 9% of sequenced newborns and identified unanticipated childhood-onset disease risk. NC NEXUS in North Carolina evaluated exome sequencing in newborns to assess diagnostic utility and parental preferences. The Genomics England Newborn Genomes Programme plans to screen approximately 100,000 UK newborns for roughly 200 actionable conditions. GUARDIAN in New York screens for over 250 actionable conditions using DNA sequencing. BeginNGS is an industry-academic consortium developing a gene list for genomic NBS.

Controversies and Challenges

Expanding Beyond Wilson and Jungner

Genomic NBS would identify conditions for which no treatment currently exists, challenging the fundamental screening principle of actionability. The definition of "actionable" is broadening, with reproductive planning for future pregnancies, preparing the family, connecting to support networks, and clinical trial enrollment being argued as benefits even without direct treatment. Significant tension exists between maximizing detection and minimizing harm from uncertain or non-actionable findings.

Consent and Autonomy

Traditional NBS operates under implied consent or public health mandate, but adding genomic sequencing raises the bar for informed consent. Parental consent for genomic NBS is generally considered necessary given the broader scope and implications. Questions arise about what information parents should receive before consenting, given that the complexity of genomic results challenges meaningful informed consent. The child's future autonomy regarding their own genomic data must also be considered in any consent framework.

Variant Interpretation in Newborns

Variants of uncertain significance are inevitable with genomic approaches and create uncertainty and potential for harm in a newborn screening context. Incomplete penetrance means that many genetic conditions have variable penetrance, and identifying a variant does not guarantee disease will develop. For conditions with adult onset or variable expression, a positive screening result in a newborn creates a potentially harmful label. Analytical challenges exist because some important NBS conditions, such as spinal muscular atrophy involving SMN1 deletions, require specialized assays not captured by standard sequencing.

Equity Concerns

Genomic NBS could exacerbate disparities if access is limited to well-resourced health systems. Higher VUS rates in underrepresented populations would create differential screening accuracy. Follow-up diagnostic and specialty care must be accessible to all screened families. Diverse representation in gene lists and variant databases is essential for equitable screening.

Data Storage and Privacy

Newborn genomic data would need to be stored long-term, and governance frameworks for decades-long data management are needed. Questions about who has access to a child's genomic data as they grow into adulthood remain unresolved. Implications for insurance, employment, and other domains exist if genomic data is linked to newborn screening records. The potential for function creep, where data collected for NBS purposes is repurposed for research or other applications, raises additional concerns.

Evidence from Pilot Studies

BabySeq Key Findings

The BabySeq study found that 9.4% of sequenced healthy newborns had a medically actionable finding, with most findings being for conditions not on the existing NBS panel. Parental distress was not significantly increased in the sequencing group at short-term follow-up. Some parents experienced ambiguous or uncertain results that required ongoing genetic counseling. Follow-up costs and clinical actions were significant for families with positive results.

Lessons Learned

Pilot studies have demonstrated that robust genetic counseling infrastructure is essential for returning genomic NBS results. A curated, evidence-based gene list is preferable to open-ended genomic analysis. Results must be clearly categorized by actionability, including immediate medical action, childhood surveillance, reproductive information, and adult-onset categories. Integration with existing public health NBS infrastructure is logistically complex.

Moving Forward

Proposed Frameworks

Tiered reporting would categorize results by urgency and actionability, returning highest-tier results automatically while offering lower-tier results as opt-in. Age-gated return would deliver childhood-actionable findings immediately while storing adult-onset and carrier results for future access when the individual reaches adulthood. Dynamic gene lists would be continuously updated based on new evidence for gene-disease validity and actionability. Embedded genetic counseling would ensure every family with a positive screen has access to timely genetic counseling.

Clinical Pearls

Genomic newborn screening can detect conditions beyond the reach of biochemical screening but introduces challenges of VUS, incomplete penetrance, and uncertain actionability that are particularly consequential in the newborn context. Informed parental consent should be the standard for genomic NBS, unlike traditional biochemical NBS which operates under public health mandates. The BabySeq trial demonstrated that approximately 9% of healthy newborns had medically actionable genomic findings, suggesting substantial potential clinical impact if scaled. Equity must be central to genomic NBS design: diverse reference populations, accessible follow-up care, and equitable deployment are prerequisites for responsible implementation.

References

1. Holm IA, Agrawal PB, Ceyhan-Birsoy O, et al. The BabySeq project: implementing genomic sequencing in newborns. BMC Pediatrics. 2018;18:225.
2. Ceyhan-Birsoy O, Murry JB, Machini K, et al. Interpretation of genomic sequencing results in healthy and ill newborns: results from the BabySeq Project. American Journal of Human Genetics. 2019;104(1):76-93.
3. Wilson JMG, Jungner G. Principles and Practice of Screening for Disease. WHO Public Health Papers No. 34. World Health Organization; 1968.
4. Roman TS, Crowley SB, Engel KL, et al. Genomic sequencing for newborn screening: results of the NC NEXUS Project. American Journal of Human Genetics. 2020;107(4):596-611.

Read this lecture as Markdown