Noninvasive Prenatal Lab Test Determines Rhesus D Incompatibility

A noninvasive lab prenatal test to detect Rhesus D (RhD) incompatibility is based on cell free nucleic acid assessment. The laboratory-developed test (LDT) is performed on a real-time polymerase chain reaction (RT-PCR) platform.

The SEQureDx technology is a novel approach to genetic screening. Unlike current standards of harvesting placental tissue cells as is required for chorionic villus, or entering the uterus to sample the amniotic fluid surrounding the baby as is performed with amniocentesis, SEQureDx technology extracts fetal nucleic acid material safely and comfortably from a simple blood specimen collected from the mother to determine the genetic status of the fetus. This means that effective screening could be accomplished in the future without the risks associated with disturbing the amniotic fluid that surrounds the baby in the uterus.

Sequenom, Inc. (San Diego, CA, USA) announced the New York State approval of the SEQureDx prenatal test, which will be marketed by Sequenom's nonexclusive licensee, clinical laboratory improvement act (CLIA)-certified, New York State permitted laboratory, Lenetix medical screening laboratory, (Mineola, NY, USA).

Rhesus D (RhD) blood group incompatibility between a pregnant woman and her fetus is a significant problem due to the possibility of maternal alloimmunization and consequent hemolytic disease of the newborn. Alloimmunization most frequently occurs when an RhD negative mother is exposed to red blood cells of an RhD positive fetus, producing maternal antibodies against the RhD antigen. Although the pregnancy in which alloimmunization first occurs results in an unaffected child, future children are at substantial risk of anemia and in the worst cases, fetal death. In the U.S. alone, RhD incompatibility occurs in more than 10% of all pregnancies.

Anti-D immunoglobulin is routinely administered to RhD negative women at 28 weeks and after the birth of the child has helped prevent maternal alloimmunization. This prophylactic treatment prevents alloimmunization in 96% of cases. For the remaining 4% of women, approximately 20,000 pregnancies in the United States per year, it is important to establish the RhD type of the fetus. This is frequently performed by amniocentesis between weeks 16 and 20 of the pregnancy. If testing shows that the fetus is RhD negative, no further testing is required. If positive, the pregnancy is closely monitored to ensure the health of the baby.

RhD is our pioneering test and will serve in assisting in preparing us in developing and launching other tests such as FetalXY and Down syndrome, said Harry Stylli, Ph.D., Sequenom's president and CEO. Genetic-based noninvasive prenatal testing could complement and potentially present a paradigm shift from current invasive testing procedures such as amniocentesis. Tests based on our SEQureDx Technology can be performed from a simple maternal blood sample, which could allow obstetric and fetal maternal specialists to successfully intervene early in the pregnancy to improve outcomes.


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