NIPS: Microdeletions, Macro Questions

At the recent National Society of Genetic Counselors Annual Education Conference in New Orleans, a presentation raised some important questions about noninvasive prenatal screening (NIPS). According to the speaker, a woman with a vanishing twin pregnancy underwent NIPS with an expanded microdeletion panel and the results showed findings “suggestive” of a chromosomal microdeletion syndrome.

The patient underwent amniocentesis with a SNP microarray and the results were normal. In a follow-up call with the NIPS lab, the genetic counselor learned that multiple copy number variants were observed (not originally reported) in the original sample. The lab suggested that these variants could be associated with a malignancy or fibroid tumor (and were of course unlikely to be associated with a microdeletion syndrome in the fetus).

As a result of this genetic counselor’s follow-up phone call and due diligence, the patient underwent an extensive work up for possible cancer, but no explanation was found. NIPS was repeated and this follow-up study was normal.

My first thought in hearing this case was – That poor woman! First a lost twin pregnancy, then...