Image: The Qubit Quantitation Fluorometer platform quantifies DNA, RNA, and protein (Photo courtesy of Life technologies).
The alternative DNA test offers clinically relevant genetic information to identify why a miscarriage may have occurred years earlier and it is possible to identify chromosomal variants and abnormalities in nearly 50% of the samples.
The technique is called rescue karyotyping, and allows physicians to obtain important genetic information from tissue that had not been tested at the time of the miscarriage. As part of standard hospital protocol, tissue from miscarriages is embedded in paraffin for archival use and the karyotyping test is performed on DNA extracted from this tissue.
Scientists from the Albert Einstein College of Medicine (Bronx, NY, USA) carried out a retrospective study of 20 samples from 17 women, and genetic testing was successfully performed on 16 samples that had been archived for as long as four years. A slide from the formalin-fixed paraffin-embedded (FFPE) block was reviewed by a pathologist and the area of fetal tissue circled. Fetal or chorionic villus cells were macro-dissected from this circled area to reduce maternal cell contamination (MCC) and subjected to DNA extraction.
The genomic DNA (gDNA) concentration was measured using Nanodrop 1000 (Thermo Fisher Scientific; Waltham, MA, USA) and quantified by Qubit 2.0 Fluorometer (Life Technologies; Carlsbad, CA, USA). Array-based comparative genomic hybridizations (aCGH) were run on Agilent CGH arrays (Agilent Technologies; Santa Clara, CA, USA) for high resolution testing. Of the 16 specimens that had sufficient DNA for aCGH analysis, 8 (50.0%) were euploid, and 8 (50.0%) showed copy number variants potentially responsible for the pregnancy loss. When conventional karyotyping testing is unavailable for any reason, rescue karyotyping provides a critical alternative method to uncover the genomic information.
Zev Williams, MD, PhD, an assistant professor of obstetrics and gynecology and lead author of the study said, “Given the ease of obtaining results, even if a delay in testing occurs, this new test may provide a useful technique to gain a better understanding as to why miscarriage occurs in some women. I have seen women in tears because testing was not done at the time of the miscarriage and they feared they would never learn why it happened. Now we are able to go back and often get the answers we need.” The study was published on March 3, 2014, in the journal Reproductive Biology and Endocrinology.
Albert Einstein College of Medicine
Thermo Fisher Scientific