During pregnancy, the developing embryo sheds cells which are absorbed by the maternal blood stream. In most cases the cells are destroyed and cell-free fetal DNA remains. This fetal DNA is present in the mother's blood for many hours. And during pregnancy, there is a constant supply of this fetal DNA. Detecting genetic mutations and abnormalities has become an exciting prospect in diagnosis because of the less invasive detection - only requiring a blood sample from the mother. A recent paper was published comparing the accuracy of this method. Sensitivity and specificity were both 100% for trisomy 21. This diagnosis was made using DNA sequence reading by Verinata. But the company Sequenom is also capable of doing this. More companies are sure to emerge. The mean gestational age at the time of testing was 15 weeks. In future, tests such as these will ease the physical stress of diagnosis compared to current methods and also allow more time for pregnancy and family planning, and arrangement of medical support. Importantly, such testing will help those rural areas lacking obstetric expertise.
Randal
Randal
