The ACMG steps out from the crowd with NIPS policy statement

One of these things is not like the other

Along with the ISPD, the American College of Medical Genetics and Genomics (ACMG) issued its own policy statement on the newest form of prenatal testing for Down syndrome. The ACMG statement says some of the same things as the other professional medical organization positions, but it sets itself apart on several key points.

Since November 2012, ACOG, NSGC, ISPD, and the ACMG have issued statements on Non-Invasive Prenatal Screening (NIPS). First, let’s cover what the ACMG statement shares in common with these other statements before covering some of the key ways the ACMG sets itself apart:

• NIPS is a screening test; invasive testing is still necessary for a diagnosis.
• NIPS is not a routine prenatal test.
• Pretest counseling needs to be provided by a trained professional “to ensure patients make informed decisions.”
• NIPS has higher detection rates than other screening tests and can reduce the number of women who choose to have invasive testing.
• NIPS does not screen for open neural tube conditions.
• NIPS has not been shown to be reliable in pregnancies with more than one fetus.
• Patients should receive posttest counseling.
• Like the ISPD, the ACMG “encourages providers of NIPS technology to make serious efforts to provide the more clinically relevant metrics” and calls for studies that compare the effectiveness of the various brands of NIPS available.

On these points, there is professional consensus. The ACMG statement, however, sets itself apart from the other professional societies’ statements with the following points:

•  The very acronym to refer to the new testing is provided by the ACMG statement: “NIPS,” to emphasize that it is Non-Invasive Prenatal Screening.
  
• As I wrote about here, the ACMG makes clear that NIPS is testing DNA from the placenta, not the fetus itself, and therefore it “may not reflect the true fetal karyotype.”
• NIPS will not detect about half of all the conditions identified by amniocentesis. More specifically, for mothers younger than 35, NIPS will not identify 75% of the conditions that amnio will; for mothers over 35, NIPS will not identify 43 percent of conditions that amnio will.
• Also, as I wrote here, while there is consensus on the need for pre- and post-test counseling, and some of the statements cover what should be discussed about the characteristics of NIPS results. The ACMG goes further to state that patients should be provided accurate information about the condition tested for, and specifically recognizes the resources available for Down syndrome that provide this accurate information (these resources are included in the list at this site’s Prenatal Resources page).

And, while ACMG steps out from the crowd with the listed points, where the ACMG steps out the most is in what its statement does not say.

ACOG, NSGC, and ISPD all limit NIPS to high risk patients. The ACMG notably is silent. Therefore, a practitioner may offer NIPS to any expectant patient and not be acting contrary to the ACMG’s policy statement. This is a significant difference, since the ACMG would allow offering NIPS to the millions of pregnant women each year in the United States, while every other professional organization would limit it to just the few hundred thousands of expectant mothers considered high risk.

What do you think about ACMG being silent on who NIPS should be made available to, when the professional societies of obstetricians, genetic counselors, and professionals engaged in prenatal diagnosis all state that NIPS should only be available to high risk patients?