Researchers have identified a new way to identify the father from the fetal DNA by the eighth week of pregnancy. This new method is reported in the, New England Journal of Medicine.
Peter Benn, PhD, director of the diagnostic medical genetics laboratories at the University of Connecticut Health Center in Farmington, feels that the new test is a significant step in prenatal diagnosis. In one of the earlier studies the same test was used by the researchers to determine whether the fetus has Down syndrome. The new technology will allow bypassing amniocentesis and chorionic villus sampling for identifying genetic disorders. Both amniocentesis and chorionic villus sampling may cause infections, miscarriages, and birth defects and moreover, these tests cannot be done before 10 to 15 weeks of pregnancy.
Jill Rabin, MD, chief of ambulatory care, obstetrics, and gynecology at Long Island Jewish Medical Center in New Hyde Park, claims that prenatal diagnosis was dependent on invasive tests that could be done only during the later stages of pregnancy. “The present study has given a study in which a blood test would give a result based on what women could make a decision whether to continue with the pregnancy or not," adds Rabin. “The new test is a cutting-edge one, which is very exciting," says Rabin.
As per the earlier belief fetal DNA was floating in mother’s blood in very small amounts which was very difficult to find and analyze. According to Ravinder Dhallan, MD, PhD, chairman and chief executive of Ravgen Diagnostics in Columbia, one of the reasons why it was thought to be rare is the fact that mother’s blood cells burst during sample collection and dilute the fetal DNA. Dhallan was able to isolate enough amount of fetal DNA by mixing a fixative agent into the blood sample. “Mother’s white blood cells were made stiff by the application of fixative”, says Dhallan. Thus researchers were able to get 25% fetal DNA in the place of 1%.
Analysis of the fetal DNA helps to compare the differences in the gene sequences of the mother and the fetus. Even a single letter difference in the gene sequence matters as this may match with the paternal gene sequence. A sample of DNA from the father can help to confirm paternity or exclude it. In the study, researchers were able to correctly identify the father when blood samples from biologic mothers and fathers grouped with unrelated men were analyzed. “This test would be helpful in so many situations in which there is a need to identify the paternity before the baby is born," says Dhallan.