What Potent Blood: Non-Invasive Prenatal Genetic Diagnosis and the Transformation of Modern Prenatal Care

Article excerpt

What potent blood hath modest May,

What fiery force the earth renews,

The wealth of forms, the flush of hues....

-Ralph Waldo Emerson1

I. INTRODUCTION

Someday soon, virtually any pregnant woman2 will be able to learn - with 98-99% accuracy - whether her fetus has contracted a serious genetic disorder by undergoing nothing more than an inexpensive, non-invasive blood test. For years, scientists have sought a method of prenatal testing that could boast both high levels of accuracy and low levels of risk. The most promising solution lies in an exciting recent discovery: tiny quantities of fetal cells and DNA cross over into the mother's bloodstream during pregnancy.3 If the fetal genetic material can be successfully isolated from the maternal blood, it can be used to diagnose a number of genetic disorders, such as Down Syndrome, cystic fibrosis, Tay-Sachs disease, and sickle cell anemia. Indeed, researchers have spent the last decade developing ways to accomplish this.

These new blood tests promise significant advantages over present methods of prenatal testing. Unlike current prenatal screening tests, like ultrasound and chemical assays, this new technology could attain extremely high levels of accuracy and be performed as early as 6-10 weeks' gestation.4 Unlike current prenatal diagnostic tests, like amniocentesis and chorionic villus sampling ("CVS"), the new genetic tests would be non-invasive; as such, they would pose no risk of miscarriage and could be offered to women of all ages and risk levels.5

This article introduces the emerging technology of non-invasive prenatal genetic diagnosis ("NPGD") and argues for its impending potential to revolutionize modern prenatal care. In particular, clinical implementation of NPGD - which is non-invasive, accurate, and inexpensive - could dramatically increase the availability of prenatal genetic testing to all pregnant women, change the standard of care, reduce the incidence of serious genetic disorders, and raise (with even greater force and urgency than past advancements in genetics) numerous ethical, legal, and social questions.

Part II offers a brief overview of the two modern methods of prenatal genetic diagnosis:6 amniocentesis and CVS, both of which are considered "invasive" procedures and pose some risk to both the mother and the developing fetus. Part III explains the science behind two potential noninvasive alternatives for prenatal genetic testing, which I call "maternal serum fetal cell sorting" ("MSFCS") and "maternal plasma DNA recovery" ("MPFDR"). Although clinical implementation of these tests is still years away, scientists expect them to offer high levels of accuracy, early intervention options, and significantly lower prices and costs. Part IV proceeds from the assumption that researchers will successfully develop a highly accurate, clinical version of NPGD and attempts to explain some of the initial legal and social implications, including: NPGD's likely effect of dramatically increasing the number of pregnant women who utilize prenatal genetic testing, its capability of becoming the new standard of care, and its potential to garner both public and private funding through insurance. Finally, Part V discusses several long-term consequences of the likely widespread use of NPGD.

II. PRENATAL GENETIC DIAGNOSIS TODAY

Today, what is termed "prenatal testing" can involve both screening and diagnostic tests. Screening tests impose a lower threshold of accuracy and merely help identify an at-risk population for additional testing, while diagnostic tests are held to stringent accuracy standards (on the order of 98-99% accuracy) and result in a conclusion regarding the fetus's disease status.7

Many women who undergo prenatal genetic testing begin with a screening test. The most common screening tests include: (1) the maternal serum α-fetoprotein ("MSAFP") assay, a maternal blood test measuring levels of α-fetoprotein, which are considerably higher in cases of Down Syndrome;8 (2) the "multiple-" or "triple-marker" screen, which measures maternal blood concentrations of α-fetoprotein, as well as two other chemicals associated with chromosomal abnormalities;9 and (3) ultrasonography, which is used to screen for physical abnormalities (e. …