Traditionally in high risk pregnancies, a Fluourescent In-Situ Hybridization (FISH) karyotype is performed on samples from the placenta or amniotic fluid to screen for prenatal diseases. This past Wednesday, two studies published in the New England Journal of Medicine, found that chromosomal microarrays, a lesser known form of genetic testing, are just as and often more effective than FISH karyotyping when testing for prenatal genetic abnormalities.  The first study found that chromosomal microarrays were able to identify additional and significant cytogenetic information above FISH.  These microarrays were also equally successful in identifying aneuploidies (extra or missing copies of chromosomes) as well as unbalanced chromosomal rearrangements.  According to Ronald J. Wapner, the lead researcher for the New England Journal of Medicine study ,“The biggest advantage of microarray is it can give us a lot more information.”

The second study used chromosomal microarray technology to analyze 532 stillbirths. The microarrays were able to determine the cause of stillbirth in 87 percent of cases, compared to 71 percent using conventional testing methods (FISH). Unlike conventional testing, microarrays are able to determine whether prenatal heart defects are caused by genetics.  The broadening access to chromosomal microarrays for high-risk pregnancies will provide prospective parents with more information about the health of their future child and allow them to make well informed decisions.