Answers in Days, Not Weeks: How Fast Genetic Testing Is Helping Seriously Ill Babies

What three 2026 studies from Dubai (Rabea et al.), South Korea (Cho et al.) and Greece (Loukas et al.) tell families about rapid genome testing in newborn and children's intensive care

When a baby in intensive care is seriously ill and doctors suspect the cause lies in the baby's genes, reading the baby's whole genetic code can now give an answer in days rather than weeks. Three new studies from Dubai, South Korea and Greece found a genetic cause in roughly a quarter to a half of the babies and young children tested, and in Dubai the results changed the care of about half of the children.

Some babies become very unwell soon after birth for reasons that are hard to pin down: blood sugar that keeps falling, seizures that will not settle, muscles that are unusually floppy, or several differences in how the body has formed. In many of these babies the cause is a change in a single gene. Genes are the instructions, written in a chemical code called DNA, that tell the body how to grow and work. Finding the exact change can explain what is happening, point to a treatment, and help parents understand what lies ahead.

How families and doctors used to search for answers

For many years, genetic testing in sick newborns happened one step at a time. Doctors would order one test, wait for the result, and then order another, a process that could take weeks or months. Studies have shown how costly that wait can be. In one large American newborn intensive care unit (NICU), more than a quarter of the babies who later died had a confirmed genetic condition, and about a third of those diagnoses came only after the baby had died [1]. In San Diego County, a review of 112 infant deaths found that single-gene conditions were the most common cause that could be identified, affecting 46 babies [2].

In 2012, doctors at Children's Mercy Hospital in Kansas City showed that a baby's entire genetic code — the "genome" — could be read and interpreted in about 50 hours, arguing that genetic answers for newborns must come quickly to be useful [3]. A trial at the same hospital, the first Newborn Sequencing in Genomic Medicine and Public Health randomised trial (NSIGHT1), then compared fast genome testing with usual tests: about 31% of babies who had the fast test received a diagnosis within four weeks, compared with about 3% of those who had usual testing [4]. Hospital programmes followed. In California, Project Baby Bear found a diagnosis for 74 of 184 babies in a median of 3 days [5], and nationwide programmes in Australia and Israel showed that the approach could work across whole countries [6][7]. Even so, fast genetic testing remains uncommon: one review estimated that it reaches fewer than 5 in every 100 of the roughly 200,000 children who might benefit each year [8]. Until recently, such programmes were also largely missing in the Middle East [9], a region where marriage between cousins is common in many families. When parents are related, their babies are more likely to inherit two copies of the same changed gene, which raises the chance of "recessive" genetic conditions [10].

What the three new studies did

The largest study, by Rabea and colleagues, describes a programme called "Little Falcon" in Dubai, United Arab Emirates [9]. It offered rapid whole-genome sequencing — fast reading of nearly all of a person's DNA — to critically ill babies and children in the city's central public NICU at Latifa Hospital and its children's intensive care unit at Al Jalila Children's Hospital. The first 100 families who agreed to take part were included; 62 children came from the newborn unit, and about half of all the children were newborns. In almost every case, both parents also gave a blood sample. This "trio" approach helps the laboratory tell which gene changes are inherited and which are new. The researchers compared these children with 100 similar children from the same health system who had standard genetic tests in the years before the programme started. The sequencing company Illumina supported the programme by providing laboratory materials and software.

The second study, by Cho and colleagues, took place in one NICU at Samsung Medical Center in Seoul, South Korea [11]. Neonatologists (doctors who specialise in newborns) chose 20 babies for trio genome testing; the babies were between 1 and 257 days old.

The third study, called Rare-ID, included 25 babies younger than 6 months who were referred from hospitals across Greece [12]. The first 17 had exome sequencing, which reads only the parts of genes that carry instructions for making proteins, and the next 8 had whole-genome sequencing. Mostly only the baby's DNA was tested.

What they found, in everyday numbers

In Dubai, results came back in a median of about 3.4 days, compared with 38 days for standard testing [9]. Doctors found a genetic diagnosis in 53 of the 100 children, compared with 30 of 100 before the programme, and changed care for 53 of 100 children, compared with 18 of 100. Changes included starting a specific medicine or diet, avoiding unnecessary tests, arranging a specialist review, planning surgery, or, for some children, focusing on comfort care. When parents were closely related, 28 of 35 children (80%) received a diagnosis, compared with 16 of 47 (34%) when parents were unrelated. One 2-month-old was diagnosed with a rare condition called Wolman disease in about two days and started treatment roughly two weeks before an enzyme test confirmed the diagnosis.

In Seoul, results took an average of 5.5 days, and 10 of the 20 babies received a diagnosis [11]. For all ten, the result changed something about their care, such as medicines, further tests or follow-up plans. In one baby thought to have a kidney condition, the test pointed to a different kidney disorder and spared the baby a kidney biopsy. Two other babies were already receiving treatment based on their doctors' best guess for a condition that stops the body from clearing ammonia, a waste product; the test identified the exact condition, called ornithine transcarbamylase deficiency, and each baby was given a specific supplement.

In Greece, most of the babies (21 of 25) had problems affecting the brain or nerves, such as seizures or weak muscle tone. Seven of the 25 babies (28%) received a definite diagnosis [12]. This study did not systematically track how fast results arrived or whether treatment changed.

What this could mean for your family

If your baby's doctors suggest rapid genome testing, it usually involves a small blood sample from your baby and, where possible, from both parents. In Dubai, a genetic counsellor — a specialist who explains genetic testing and results — met families before testing to explain it and ask for consent, and passed the results to the baby's medical team as soon as the analysis was finished [9]. Families could also choose whether to learn about extra findings unrelated to the baby's current illness, such as carrier status for other conditions.

There are three broad kinds of result. The test may find a clear cause. It may find a "variant of uncertain significance", a gene change whose meaning is not yet known; laboratories follow international rules to decide how confidently a change can be linked to illness [13]. Or it may find nothing, which does not completely rule out a genetic condition [12]. Even a negative result can help: in Dubai, 8 of the 47 children without a diagnosis still had a change in care [9].

Some results bring hard news. A diagnosis can help families and doctors make decisions about comfort-focused care, and in Seoul two answers arrived after the baby had died but still helped those families understand what had happened [11]. Because most Dubai diagnoses were recessive, many parents learned that each future pregnancy would carry a 1 in 4 chance of the same condition, and could discuss options for testing in future pregnancies [9].

If testing is offered, it is reasonable to ask how long results are likely to take, who will explain them, what happens if the answer is uncertain, and whether you would like to hear about findings unrelated to your baby's current illness. There is no right or wrong choice about extra findings, and the care team should give you time to decide.

Reasons for caution

These studies were not designed to prove that fast testing caused better results. The Dubai comparison group was tested in earlier years, when testing practices were different [9]. The Korean and Greek studies were small, and in Korea doctors chose which babies to test [11]. The studies also measured success in different ways, so their numbers should not simply be added together. Research has shown that smaller studies often report more benefit than larger ones [14]. Finally, testing a sick baby to find a cause is different from screening healthy newborns, where findings can be harder to interpret [15]; that topic is covered in our article on genome sequencing in newborn screening.

What researchers are working on next

Experts say the next steps are making these services available fairly to every family who needs them, starting tests promptly and supporting families throughout [16]. The Korean team reports that a larger study across many hospitals is under way [11], and the Dubai team plans to move toward government and insurance funding so that more families can benefit [9].

The bottom line

Fast genome testing is moving from research into everyday intensive care in very different parts of the world. In these studies it found answers for many seriously ill babies within days, and those answers often changed their care. It cannot explain every illness, and the results need careful explanation, but for families facing uncertainty it can bring clarity much sooner than before.

References

  1. Wojcik MH, Schwartz TS, Yamin I, et al. Genetic disorders and mortality in infancy and early childhood: delayed diagnoses and missed opportunities. Genet Med. 2018;20(11):1396-1404. doi:10.1038/gim.2018.17 ↩
  2. Owen MJ, Wright MS, Batalov S, et al. Reclassification of the Etiology of Infant Mortality With Whole-Genome Sequencing. JAMA Netw Open. 2023;6(2):e2254069. doi:10.1001/jamanetworkopen.2022.54069 ↩
  3. Saunders CJ, Miller NA, Soden SE, et al. Rapid whole-genome sequencing for genetic disease diagnosis in neonatal intensive care units. Sci Transl Med. 2012;4(154):154ra135. doi:10.1126/scitranslmed.3004041 ↩
  4. Petrikin JE, Cakici JA, Clark MM, et al. The NSIGHT1-randomized controlled trial: rapid whole-genome sequencing for accelerated etiologic diagnosis in critically ill infants. NPJ Genom Med. 2018;3:6. doi:10.1038/s41525-018-0045-8 ↩
  5. Dimmock D, Caylor S, Waldman B, et al. Project Baby Bear: Rapid precision care incorporating rWGS in 5 California children's hospitals demonstrates improved clinical outcomes and reduced costs of care. Am J Hum Genet. 2021;108(7):1231-1238. doi:10.1016/j.ajhg.2021.05.008 ↩
  6. Lunke S, Bouffler SE, Patel CV, et al. Integrated multi-omics for rapid rare disease diagnosis on a national scale. Nat Med. 2023;29(7):1681-1691. doi:10.1038/s41591-023-02401-9 ↩
  7. Marom D, Mory A, Reytan-Miron S, et al. National Rapid Genome Sequencing in Neonatal Intensive Care. JAMA Netw Open. 2024;7(2):e240146. doi:10.1001/jamanetworkopen.2024.0146 ↩
  8. Kingsmore SF, Nofsinger R, Ellsworth K. Rapid genomic sequencing for genetic disease diagnosis and therapy in intensive care units: a review. NPJ Genom Med. 2024;9(1):17. doi:10.1038/s41525-024-00404-0 ↩
  9. Rabea F, Aljasmi I, Jain R, et al. Citywide implementation of a rapid whole-genome sequencing program for critically ill pediatric patients. Nat Med. 2026;32(9):3359-3371. doi:10.1038/s41591-026-04598-x ↩
  10. Tadmouri GO, Nair P, Obeid T, Al Ali MT, Al Khaja N, Hamamy HA. Consanguinity and reproductive health among Arabs. Reprod Health. 2009;6:17. doi:10.1186/1742-4755-6-17 ↩
  11. Cho HW, Kim JM, Park SH, et al. Accelerating genetic diagnosis in the NICU: neonatologist-driven rapid whole genome sequencing. Sci Rep. 2026;16(1):22165. doi:10.1038/s41598-026-52508-5 ↩
  12. Loukas YL, Anagnostopoulou K, Thodi G, et al. Rare-ID: Genomic Diagnosis in Symptomatic Neonates and Young Infants with Complex Clinical Phenotypes: A Descriptive Cohort Study. Genes (Basel). 2026;17(8):952. doi:10.3390/genes17080952 ↩
  13. Richards S, Aziz N, Bale S, et al. Standards and guidelines for the interpretation of sequence variants: a joint consensus recommendation of the American College of Medical Genetics and Genomics and the Association for Molecular Pathology. Genet Med. 2015;17(5):405-424. doi:10.1038/gim.2015.30 ↩
  14. Callahan KP, Mueller R, Flibotte J, Largent EA, Feudtner C. Measures of Utility Among Studies of Genomic Medicine for Critically Ill Infants: A Systematic Review. JAMA Netw Open. 2022;5(8):e2225980. doi:10.1001/jamanetworkopen.2022.25980 ↩
  15. Ceyhan-Birsoy O, Murry JB, Machini K, et al. Interpretation of Genomic Sequencing Results in Healthy and Ill Newborns: Results from the BabySeq Project. Am J Hum Genet. 2019;104(1):76-93. doi:10.1016/j.ajhg.2018.11.016 ↩
  16. Stark Z, Ellard S. Rapid genomic testing for critically ill children: time to become standard of care?. Eur J Hum Genet. 2022;30(2):142-149. doi:10.1038/s41431-021-00990-y ↩