Noninvasive fetal rhesus D genotype determination by using circulating cell-free fetal DNA (ccffDNA)‎ in peripheral blood of pregnant women in Syria

Abstract EN

Objective: Accurate prediction of fetal RHD Fetus and Newborn (HDFN), rather than invasive procedures such as amniocentesis, or chorionic villus sampling.

This study aims to assess the concordance between RHD genotyping by conventional PCR using ccffDNA from mother’s peripheral blood, and the newborn RhD phenotype.

Methods: A prospective cohort study was carried out on 60 RhD-negative pregnant women rangingfrom 7-38 weeks of pregnancy (22.8±6.1 weeks), who attended Maternity university hospital in Damascus, Syria during the period from January 2019 to October 2019.

There were 14 out of 60 (23.3%) RhD alloimmunized women.

Twin pregnancies were excluded.

ccffDNA was extracted from peripheral blood of pregnant mothers by QIAamp DSP virus kit, and then PCR was done at Hematopoietic Stem Cell Transplant LAB (H.C.S.T) at Pediatric Hospital, Damascus, to determine fetal RHD genotype by amplification of exon 7, exon 10.

Results were compared with newborn RHD phenotype done on neonate cord blood.

Results: We correctly diagnosed 4/55 cases (7.3%) as RHD negative fetuses, and 51/55 cases (92.7%) as RHD positive fetuses, and they were in different pregnancy trimesters.

This study showed high concordance between the results of fetal RHD genotyping using ccffDNA in all pregnancy trimesters, and newborns RhD phenotype.

Sensitivity and specificity were both 100%, negative predictive value (NPV) and positive predictive value (PPV) were 100%.

Conclusions: A non-invasive prenatal diagnosis of RHD is an appropriate alternative to an invasive prenatal IPD diagnosis, which will be a significant step in the clinical management of alloimmunized RHD women.