What is the diagnostic yield of exome sequencing for prenatal genetic disorders?
Exome sequencing is a test that looks at the protein-coding parts of DNA to find the cause of genetic disorders. For prenatal cases, this test identifies a specific genetic diagnosis in roughly 19% of patients 3. The test is especially useful for certain conditions, such as nonimmune hydrops fetalis, where it found a cause in 29% of cases 5.
What the research says
A large study of 3,008 prenatal, neonatal, and pediatric cases found an overall diagnostic yield of 19.0% 3. This means that in about one out of five cases, the test identified a genetic variant that explained the patient's symptoms. Factors like having multiple clinical signs increased the chance of finding a diagnosis 3.
The test performs well across different genetic backgrounds. Research involving 845 diverse cases showed that diagnostic yield was not lower for patients with non-European ancestries 67. This suggests the test is equally effective for people of African, Native American, East Asian, European, Middle Eastern, and South Asian descent 67.
For specific conditions, the results can be even better. In a study of 127 cases of nonimmune hydrops fetalis, exome sequencing identified a genetic cause in 37 cases, or 29% of the group 5. Common causes found in these cases included disorders affecting the RAS-MAPK pathway, inborn errors of metabolism, and musculoskeletal disorders 5.
What to ask your doctor
- What specific genetic conditions does my baby have that might be found with exome sequencing?
- How likely is it that this test will find a cause for my baby's symptoms?
- Does my baby's genetic background affect how well this test works?
- What happens if the test does not find a clear genetic cause?
This question is drawn from common patient questions about Genetics & Precision Medicine and answered using cited medical research. We do not provide individualized advice.