OBJECTIVE: To evaluate the effectiveness of the fetal KEL and RHCE genotype assessment in alloimmunized pregnant women by minisequencing. DESIGN: Prospective cohort study. SETTING: Obstetrics and Gynecology Clinic of the Faculty of Medicine UP and the University Hospital Olomouc; Institute of Medical Genetics of the Faculty of Medicine UP and the University Hospital Olomouc; Transfusion Department of the University Hospital Olomouc; Institute of Biophysics of the Faculty of Medicine UP Olomouc. SUBJECT AND METHOD: In the years 2001-2019, 366 samples of pregnant women in the first and second trimester were assessed KEL (n = 327) or RHCE (n = 39) genotype from the free fetal DNA circulating in the peripheral blood by minisequencing. The genotype of the fetus was verified from the buccal smear of the newborn. RESULTS: The KEL genotype was assessed in 327 women (the presence of a variant of the KEL1 alele, which corresponds to the presence of the erythrocyte antigen “K“. The analysis failed in 2 cases (2/327), 16 heterozygote women (KEL1/KEL2) were excluded and in the case of 309 homozygote women (KEL2/KEL2) the fetal KEL genotype was assessed. In the case of 95.8% of the fetuses (296/309) and 95.5% of the newborns (295/309), the KEL2/KEL2 genotype was assessed. In the case of 4.2 % of the fetuses (13/309) and 4.5% of the newborns (14/309), the KEL1/KEL2 genotype was assessed. The sensitivity was 92.86%. The specificity was 100%. The RHCE genotype was assessed in 39 women. In the case of 22 women, the presence of a variant of the RHCE gene, which corresponds to the presence of the erythrocyte antigen “C“/“c“, was assessed. 5 heterozygote women (C/c) were excluded. In the case of 11 homozygote women (C/C), the RHCE genotype was assessed. In the case of 64% (7/11) of the fetuses and newborns, the C/c genotype was assessed, in the case of 36% (4/11) the C/C genotype was assessed. In the case of 6 homozygote women (c/c), the RHCE genotype was assessed. In the case of 67% (4/6) of the fetuses and newborns, the C/c genotype was assessed, in the case of 33% (2/6) the c/c genotype was assessed. The sensitivity and specificity were 100%. In the case of 17 women, the presence of the variant of the RHCE gene, which corresponds to the presence of the erythrocyte antigen “E“/“e“, was assessed. 1 heterozygote woman (E/e) was excluded. In the case of 16 homozygote women (e/e), the RHCE genotype was assessed. In the case of 75% (12/16) of the fetuses and newborns, the e/e genotype was assessed, in the case of 25% (4/16) the E/e genotype was assessed. The sensitivity and specificity were 100%. CONCLUSION: The minisequencing method using the capillary electrophoresis enabled a reliable detection of the fetal KEL and RHCE genotype from the peripheral blood of pregnant women.

Risk Minimization of Hemolytic Disease of the Fetus and Newborn Using Droplet Digital PCR Method for Accurate Fetal Genotype Assessment of RHD, KEL, and RHCE from Cell-Free Fetal DNA of Maternal Plasma