January 9, 2018, Washington DC - Prenatal screening and testing has changed dramatically since the 1970s. The introduction of ultrasound technology and the more recent completion of DNA sequencing of the human genome have led to tremendous advances in prenatal diagnosis. With the availability of genomic sequencing, much more detailed genetic information related to the fetus can now be uncovered. As DNA technologies are developed and applied to prenatal testing, unique challenges and questions arise about their applicability to various populations. In response, three national organizations issued a joint position statement today entitled, "The use of diagnostic genome-wide sequencing for fetal diagnosis."
The joint position statement was published today online in Prenatal Diagnosis and was issued jointly by the International Society for Prenatal Diagnosis (ISPD), the Perinatal Quality Foundation (PQF), and the Society for Maternal-Fetal Medicine (SMFM).
The more comprehensive information that is available with sequencing can improve the ability to uncover the cause of birth defects, but the practice is not without challenges and complexities that need to be considered. Outlined in greater detail in the newly released position statement, the consensus opinion for when the genome-wide testing should be considered are summarized:
DNA sequencing is beginning to be used for the evaluation of fetuses with suspected genetic disorders for whom standard chromosomal testing has already been performed and is uninformative. In some cases, sequencing may be offered concurrently with standard testing when expert genetic opinion determines that that is unlikely to identify a cause for the presenting fetal phenotype.
Routine use of genome-wide sequencing as a diagnostic test is not currently recommended due to insufficient validation data and knowledge about the benefits and pitfalls.
Testing is currently best done in trios (both parents and the fetus). Parents require genetic experts to provide pre- and post-test counseling and for result disclosure; many specific counseling points are recommended as minimal for the informed consent process and to enhance the patient/parent understanding.
The indications that might warrant consideration of prenatal genomic testing include: a fetus with ultrasound-identified anomalies that might suggest a genetic etiology, but the standard genetic testing has not identified the cause; cases in which expert genetic consensus suggests a high likelihood of a genetic etiology; couples with a previous affected fetus, stillbirth or child with no genetic diagnosis and the identification of a recurrent pattern of anomalies in a new pregnancy.
A list of laboratory recommendations for consistent test quality, DNA variant interpretation, and return of results to parents are listed in the new position statement.
"In an effort initiated by the Position Statement Committee of ISPD, representatives from the three organizations, ISPD, PQF and SMFM, recognized the importance of a shared, consistent message to healthcare providers about the application of new technologies to prenatal and perinatal care," said Ignatia Van den Veyver, MD, a maternal-fetal medicine specialist, ISPD President and co-author of the position statement. "This resulted in a productive, collaborative effort to develop this joint position statement. We envision this as the beginning of similar future collaborations that will benefit prenatal care providers and patients in the current rapidly evolving genomic era."