20 Clinical OMICs July/August 2017 www.clinicalomics.com
Helen Albert
Contributing Editor
A
Noninvasive
Future
Prenatal Genetic Testing Looks to
Single-Cell Methods as the Next Frontier
P
renatal genetic testing has advanced enormously over the last few decades.
Amniocentesis and chorionic villus sampling (CVS) have been performed
to diagnose fetal abnormalities for many years, but these tests are invasive
and not without problems. The risk for miscarriage is low (approximately 1 in
1000 for amniocentesis and 1 in 500 for CVS), but it has prompted a long quest to
find the perfect noninvasive prenatal test.
The recent advent of fetal cell-free DNA (cfDNA) tests has significantly changed
the prenatal testing landscape. "We published the first large-scale trial on the
non-invasive Down syndrome tests in January 2011 and within 10 months the
test was launched in the USA," prenatal cfDNA test founder
Dennis Lo, M.D., Ph.D., Chinese University of Hong Kong,
told Clinical OMICs. "The test is now used in over 90 coun-
tries and millions of tests are done every year."
With a greater accuracy than standard noninvasive screen-
ing (maternal serum testing for protein markers and ultra-
sound scanning) for predicting risk of more common genetic
disorders such as Down (trisomy 21), Patau (trisomy 13), and Edwards (trisomy
18) syndromes, cfDNA testing has become a popular option for patients and
providers.
While these tests have improved the accuracy of early screening for more com-
mon aneuploidies, they currently only have limited accuracy for detecting rarer
conditions such as DiGeorge syndrome (22q11 deletion). They also still require
an invasive diagnostic test to definitively confirm the result, as false positives do
occur.
The presence of fetal cells in maternal blood was first detected in 1969. Since
then, extracting these cells for analysis has become the "Holy Grail" of prena-
tal testing with many researchers and companies trying and failing to success-
fully extract and analyze these cells. In 2016, a number of papers were published
"A simpler, safer, and accurate
prenatal diagnosis based
on fetal cells is the future."—
Ripudaman Singh, Ph.D., chief
technical officer, Arcedi Biotech.