JAMA Pediatrics December 01, 2021

Effect of Whole-Genome Sequencing on the Clinical Management of Acutely Ill Infants With Suspected Genetic Disease: A Randomized Clinical Trial (NICUSeq)

Ian D. Krantz, Livija Medne, Joan M. Weatherly, et al.

Bottom Line

In acutely ill infants with suspected genetic diseases, early whole-genome sequencing doubled the rate of diagnostic yield and significantly increased actionable changes in clinical management compared to standard-of-care testing.

Key Findings

1. Early Whole-Genome Sequencing (WGS) resulted in a change of clinical management (COM) in 21% of infants compared to only 10% in the delayed WGS (standard of care) group (P = 0.009).

2. Diagnostic efficacy (yield) was doubled in the early WGS arm at 60 days, identifying a molecular diagnosis in 31% of infants versus 15% in the standard-of-care arm (P = 0.003).

3. The most common changes in management driven by early WGS included targeted subspecialty referrals, alterations in medication, and the redirection or initiation of surgeries and procedures.

4. Among the patients who received a diagnosis via WGS, the turnaround time to return results was successfully maintained at a median of approximately 15 days.

Study Design

Design

Randomized Clinical Trial

Open-Label

Sample

354

Patients

Duration

60 days

Median

Setting

Multicenter, US

Population Acutely ill infants between 0 and 120 days of age who were admitted to a neonatal or pediatric intensive care unit with a suspected genetic disorder.

Intervention Early whole-genome sequencing (WGS), with results returned to the clinical team within 15 days of enrollment.

Comparator Delayed whole-genome sequencing, with results returned at 60 days (serving as standard-of-care clinical management during the 60-day observation period).

Outcome The proportion of infants with a change in clinical management (COM) at 60 days post-enrollment.

Study Limitations

• The study utilized a time-delayed design (60 days) to ensure all enrolled infants eventually received WGS, which limited the ability to evaluate long-term mortality, prolonged clinical outcomes, and comprehensive cost-effectiveness between WGS and standard care.

• The turnaround time for the early WGS arm was targeted at 15 days, which, while faster than standard sequencing in 2017-2019, is slower than ultra-rapid WGS protocols available today (which can return results in 2-5 days), potentially underestimating the true clinical impact of modern rapid WGS.

• The open-label nature of the trial meant that treating clinicians were aware of the genetic results, which inherently influenced subjective clinical decision-making, though this is unavoidable in diagnostic trials.

Clinical Significance

The NICUSeq trial provided highly anticipated Level 1 evidence demonstrating the clinical utility of Whole-Genome Sequencing as a first-line diagnostic test in the neonatal and pediatric intensive care settings. By proving that WGS not only ends the 'diagnostic odyssey' faster but actively changes medical management (including life-saving interventions and palliation), this trial helped catalyze the widespread adoption of rapid WGS and justified broader insurance coverage for critically ill infants.

Historical Context

Prior to this trial, genetic evaluation of critically ill infants relied on a slow, stepwise approach—often starting with chromosomal microarrays (CMA) or targeted gene panels. While earlier observational and retrospective cohort studies (such as those by Stephen Kingsmore and the Rady Children's Institute) suggested that rapid WGS could achieve high diagnostic yields and alter care, rigorous randomized controlled trials were lacking. The NICUSeq trial was designed to definitively test the hypothesis that providing WGS results earlier than standard care would directly impact real-time clinical management, filling a crucial evidence gap required by medical guidelines and payers.

Guided Discussion

High-yield insights from every perspective

Med Student

Medical Student

What is the primary difference between whole-genome sequencing (WGS) and standard-of-care genetic testing like chromosomal microarray (CMA) or targeted gene panels, and why is this distinction critical for acutely ill infants?

Key Response

WGS captures the entire genome, including non-coding regions and structural variants, whereas targeted panels only look at specific predetermined genes. In the NICU, presenting signs of genetic diseases are often atypical, evolving, or incomplete, making the broad, unbiased approach of WGS superior for rapid diagnosis compared to phenotype-driven standard panels.

Resident

The study notes an increase in actionable changes in clinical management following early WGS. As a resident admitting an infant to the NICU with a suspected genetic disease, what specific types of management changes would you expect WGS results to influence?

Key Response

WGS can guide targeted pharmacotherapy, dictate the initiation or withdrawal of invasive life-sustaining treatments (such as redirecting to palliative care for universally lethal conditions), prompt necessary subspecialty referrals, and avoid unnecessary diagnostic procedures like muscle biopsies, fundamentally altering the infant's critical care course.

Fellow

How does the interpretation of Variants of Uncertain Significance (VUS) and the utilization of trio sequencing (infant plus both biological parents) complicate the application of rapid WGS in the critical care setting?

Key Response

Trio sequencing significantly reduces the VUS burden by immediately determining if a variant is de novo or inherited, which is crucial for rapid clinical decision-making. However, obtaining parental samples in the chaotic NICU environment is logistically challenging, and navigating the disclosure of incidental findings or misattributed paternity requires advanced subspecialty counseling skills.

Attending

Given that rapid WGS doubles diagnostic yield but carries a high upfront institutional cost compared to standard testing, how should an attending physician balance the principles of resource stewardship with the potential for early diagnostic closure?

Key Response

While the initial sequencing cost of WGS is high, attendings must consider downstream savings from avoiding the diagnostic odyssey, minimizing unnecessary prolonged NICU stays, avoiding futile interventions, and optimizing targeted care. This requires shifting from a siloed view of laboratory costs to a holistic view of healthcare economics and patient-centered value.

Scholarly Review

Critical appraisal through the lens of expert reviewers and guideline development

PhD

In evaluating the clinical utility of a diagnostic test via an RCT like NICUSeq, what are the methodological challenges in defining and measuring actionable changes in clinical management as a primary endpoint?

Key Response

Actionability is inherently subjective and can vary by clinician and institutional culture. Researchers must use rigorous, standardized classification systems and blinded adjudication committees to prevent observer bias, especially since blinding treating clinicians to WGS results is ethically and practically impossible in this trial design.

Journal Editor

As a peer reviewer analyzing this unblinded pragmatic trial, what threats to internal validity exist regarding the standard-of-care control arm, and how might performance bias skew the reported rate of clinical management changes?

Key Response

Clinicians in the standard-of-care arm knew they were in a trial and might have pursued standard genetic testing more aggressively than usual (Hawthorne effect). Conversely, knowing the infant did not receive early WGS might have introduced a nihilistic bias or delayed aggressive care, making the precise quantification of WGS superiority vulnerable to unblinded performance bias.

Guideline Committee

Current ACMG guidelines increasingly recognize rapid genomic sequencing for critically ill infants. Based on the NICUSeq RCT demonstrating doubled diagnostic yield, does the evidence support upgrading rapid WGS to a strong, first-line recommendation over sequential testing for all NICU infants with suspected genetic disorders?

Key Response

The RCT provides high-quality Level 1 evidence of superiority over standard sequential testing. A guideline committee would likely use this to strongly recommend rapid WGS as a first-line test, bypassing CMA and targeted panels, emphasizing that the time-sensitive nature of NICU care necessitates the highest-yield test upfront to maximize clinical utility.

Clinical Landscape

Noteworthy Related Trials

2019

NSIGHT2 Trial

n = 213 · JAMA Pediatr

Tested

Rapid whole-genome sequencing (rWGS)

Population

Acutely ill infants with suspected genetic disease

Comparator

Rapid whole-exome sequencing (rWES)

Endpoint

Diagnostic yield and time to diagnosis

Key result: Both rWGS and rWES provided similar diagnostic yields, but rWGS yielded results slightly faster for critically ill infants.

2019

BabySeq Project

n = 314 · Am J Hum Genet

Tested

Newborn genomic sequencing (WES) plus standard newborn screening

Population

Healthy and sick newborns

Comparator

Standard newborn screening alone

Endpoint

Monogenic disease risks and clinical utility

Key result: Genomic sequencing identified unanticipated monogenic disease risks in 11 percent of newborns, prompting altered clinical management.

2020

Australian Acute Care Genomics Trial

n = 108 · JAMA

Tested

Ultra-rapid whole-exome sequencing

Population

Critically ill pediatric patients with suspected monogenic conditions

Comparator

Standard diagnostic testing

Endpoint

Diagnostic yield and rate of clinical management changes

Key result: Ultra-rapid sequencing provided a diagnosis in 51 percent of cases, leading to direct clinical management changes in a majority of those diagnosed.

Tailored to your role

Want this tailored to you?

Add your specialty or training stage to get role-specific takeaways and more questions.

Personalize this analysis