DNA Tests Can Now Detect Reasons for Severe Fetal and Newborn Conditions

A study by researchers from the University of California recently showed the potential of "high-throughput DNA-sequencing technologies" to enhance prenatal diagnosis and pregnancy results for patients who have experienced prenatal ultrasound.

In this UCSF-led research, study authors used an approach known as "exome sequencing" to determine genetic illnesses and the underlying cause in 37 or 127 nonimmune hydrops fetalis or NIHF, a life-threatening disease in which the fetus is full of fluid.

This new finding was published in The New England Journal of Medicine or NEJM's October 7, 2020, online edition.

Leading the study was a UCSF assistant professor in the Department of Obstetrics, Gynecology & Reproductive Sciences, and corresponding author Teresa Sparks, MD, MAS, and senior study author Mary Norton MD, also a professor in the same department.

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(Photo: Darwin Laganzon on Pixabay)
Researchers from the University of California recently showed the potential of ‘high-throughput DNA-sequencing technologies’ to enhance prenatal diagnosis and pregnancy results for patients who have experienced prenatal ultrasound.

NIHF Cases

The corresponding author said, the cause of most NIHF cases "is not identified with standard testing." However, when exome sequencing was applied, the researchers discovered a genetic diagnosis in almost 30 percent of previously unknown causes.

The study also specified that NIHF impacts one in every 1,700 to 3,000 pregnancies in the United States and is linked to high risks of stillbirth, preterm birth, neonatal death, and other complications.

Even though NIHF frequently results in a fatality, determining the exact genetic cause is critical, as linked outcomes differ widely in severity.

Essentially, NIHF can be considered an indicator of numerous genetic illnesses. However, evidence of abnormal fluid build-up in the fetus identified through an ultrasound test, whether it takes place under the skin, in the abdomen or around the lungs or heart, does not specify any underlying cause.

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Genetic Tests Done

Reports about this NEJM study said participants were referred from all over the United States following the identification of NIHF with prenatal ultrasound. However, no underlying genetic disease was discovered through the use of long-established approaches to detect genetic irregularities.

These traditional genetic tests, also called "karyotype and chromosomal microarray analysis," identify huge abnormalities in chromosomes, not syndromes triggered by a deficiency in a single gene as are detected in exome sequencing.

This new study describes exome sequencing "as the complete spelling out of the genetic code for DNA segments within the genome," serving as the "blueprints for proteins."

Furthermore, according to research, exome sequencing can identify even the tiniest mutations, as a change in one single-block nucleotide base pair.

Essentially, many disorders specified in the study have not formerly been reported in connection to NIHF, so the results widen knowledge of genetic illnesses that can show with the condition.

Among the most typical 37 genetic disorders indicated in the NEJM study were 11 cases that affected a crucial intracellular signaling pathway known as RAS-MAPK, four conditions of inborn metabolism errors, and four occurrences musculoskeletal disorders, and three lymphatic cases, neurodevelopmental, cardiovascular, and blood disorders.

Many of these diagnoses, according to Sparks, would have been missed as well, by "commercial gene panels." Furthermore, most mutations indicated in this research newly arose in the fetus. However, several of them were hereditary, promising to affect pregnancies in the future with the same biological father or mother.

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