Genotyping approach for non-invasive fetal RHD detection in an admixed population

TRUCCO BOGGIONE C; DI MÓNACO R; COTORRUELO C; MATTALONI S; BIONDI C; LUJÁN BRAJOVICH M; GARCÍA BORRÁS S

Blood Transfusion

SIMTI servizi

Lugar: Milán; Año: 2016 vol. 21 p. 1 - 8

1723-2007

Background: non-invasive fetal RHD genotyping can predict hemolytic disease of the fetus and the newborn in pregnancies with anti-D alloantibodies and also avoid antenatal anti-D prophylaxis in pregnant women carrying an RHD negative fetus. Considering that Argentineans? genetic background is the result of generations of intermixing between several ethnic groups, we evaluated the diagnostic performance of a non-invasive fetal RHD determination strategy to guide targeted antenatal RhD immunoprophylaxis. This algorithm is based on the analysis of four regions of the RHD gene in cell free fetal DNA in maternal plasma and maternal and paternal RHD genotyping.Materials and methods: DNA from 298 serologically D negative pregnant women between 19-28 weeks? gestation were RHD genotyped. Fetal RHD status by real time PCR was determined in 296 maternal plasma samples. In particular cases, RHDΨ and RHD-CE-Ds alleles were investigated in paternal DNA. Umbilical cord blood was collected at birth and serological and molecular studies were performed.Results: among the 298 maternal samples, 288 were D-/RHD- and 10 D-/RHD+ (2 RHD*DAR; 5 RHD-CE-Ds; 3 RHDΨ). Plasma from RHD*DAR carriers was not analysed. Real time PCR showed 210 RHD+ and 78 RHD- fetuses and 8 inconclusive results. Regarding this latter group, paternal molecular studies were useful to report a RHD negative status in 5 fetuses while only 3 remained inconclusive. All the results, except one false positive due to a silent allele [RHD(581insG)], agreed with the neonatal typing performed in cord blood.Discussion: the protocol used for noninvasive prenatal RHD genotyping proved to be suitable to determine fetal RHD status in our admixed population. The knowledge of the genetic background of the population under study and maternal and paternal molecular analysis allows reducing the number of inconclusive fetal RHD status results.