Your Baby’s Genetic Makeup

Knowing your child’s vulnerabilities early on can aid treatment. But laboratories still produce very different results. Here's what you should know.

Do you want to get the most complete data possible on your infant’s genetic makeup — a sequence of the whole genome?

Someday genome sequences may be routine or state-mandated for infants, like the current heel-prick test, which provides a blood sample examined for about 30 conditions. Down the road, data on your baby’s genome could point doctors to the best allergy medication or help prevent allergies altogether.

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Scientists sequenced the entire genome of 400 hospitalized infants from six hospitals in GEMINI, a prospective study that also included testing with a targeted gene panel. The whole genome sequence, which took only six days, led to a diagnosis for the sick infants about half the time, compared to 27 percent for the narrower panel, which took just over four days.

Overall, the information was valuable enough to inspire treatment changes for about a fifth of the struggling babies. In fact, the testing led to diagnoses of diseases no one suspected. Only a third of pretest reports from geneticists listed the disorder the study discovered.

In addition, GEMINI uncovered 134 new genetic variants that may be tied to disease with further research, which is especially helpful since the cost of genomic sequencing has dropped.

But GEMINI also showed the limits of the current science. Two labs looking at the same patient samples and records detected the same variant but interpreted it differently in more than 80 cases. And 200 babies didn’t end up with a diagnosis.

Doctors plan to use artificial intelligence to scan medical records for useful information and employ a different technique called long-read sequencing to analyze the babies’ genes.

Parents in general are eager to have more information. About 76 percent of new parents expressed interest in seeing a genome sequence, in one study. In another, nearly all of the respondents wanted information to help them prepare for a serious treatable childhood illness.

Parents who resist may not trust the test. They may be concerned about privacy. They might prefer not to hear about the risks of illnesses that may never occur, especially if no preventive strategy is available.

If doctors screen for a gene variant linked to childhood-onset colon cancer, for example, careful follow-up could lead to earlier detection and treatment. A gene variant associated with Rett syndrome halts a child’s development at six to 18 months and has no cure — but parents might want to know, anyway.

For sick newborns, the case is much clearer. Some nine percent of the nearly four million babies born in the United States each year enter the neonatal intensive care unit, with sometimes unexplained problems. Hospitals are already sequencing their genomes — sometimes focusing on the exome, the area most likely to reveal genetic problems.

Even before GEMINI, research suggested that sequencing can lead to diagnoses in tough cases. When critically ill newborns at one hospital received genomic tests, doctors landed on a diagnosis for 57 percent of them.

Among older children with neurological or developmental problems, some of whom had been looking for a diagnosis for years, genome sequencing combined with other tests led to diagnosis in 40 percent of the families, another study reported.

As genomic sequencing enters the baby wards, geneticists are researching how to make it more useful. For example, one team associated with Inova Fairfax, a large medical center serving the Washington, D.C., metro area, has identified 72 candidate biomarker genes linked to very premature births.

Other research found that genome sequencing can boost screening newborns for immunodeficiency that leaves them vulnerable to infections, in one case a child with no symptoms.

But many public health questions remain. Will genome sequencing just make doctors order more tests and interventions — and how much of those efforts will lead to better health?

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