Rhesus d and sex genotyping with fetal DNA i̇solation from maternal blood

Erythroblastosis Fetalis is a condition in which the mother is Rhesus (Rh) factor negative (-)and the fetus is Rh positive (+) and can cause causing fetal hydropsia and death. During pregnancy, invasive methods including corrion villus, amniocentesis and cordocentesis sampling could be used in the detection of Rh and gender, which all might cause miscarriages and the interference time of these procedures varies depending on the gestational week. In addition, non-invasive methods including ultrasonography, indirect and direct coombs tests are also applied. However, the sensitivity of these tests is not as high as the invasive methods. For these reasons, new methods are needed. Detection of cell free fetal DNA derived from maternal blood in recent years has enabled the development of important techniques in prenatal diagnosis. In our study, fetal Rh and gender analysis were performed by utilizing the fetal cell free DNA obtained from pregnant women whole blood with non- invasive procedure with the specific primers of exons 5 and 7 for RhD gene and SRY gene and were analized by real-time polymerase chain reaction (PCR) method. For this purpose, a total of 100 Rh (-) pregnant women were collected and cell free DNAs were isolated and Real Time PCR and Rh D and SRY analyzes were performed. 54 of the 100 cases that we collected were delivered their babies during this process and the analysis results were compared with the Turkish Ministry of Health New Born Follow up System. In the Rh D comparison, there were 3 false negative results in 54 cases and SRY gene there were 1 false negative result. The remaining 46 cases the analysis were completed and will be confirmed when the system is updated with new born babies. According to these results, the use of this technique could be applied as a genetic diagnostic test to the determinethe fetal RhD and the SRY from maternal plasma. The early diagnosis of erythroblastosisfetalis due to Rh mismatch and Congenital Adrenal Hyperplasia, Hemophilia and Duchenne Muscular Disrophy due to the presence of SRY may lead to apply this technıque as an early diagnostic test and early assessment of the result for the treatment modalities. Therefore, the unnecessary stress, treatment and the cost to the patient could be prevented. Key Words: Cell free DNA, Erythroblastosis Fetalis, Rh D, SRY, Congenital Adrenal Hyperplasia