Supplementary Material for: Clinical Potential of Effective Noninvasive Exclusion of <b><i>KEL1</i></b>-Positive Fetuses in <b><i>KEL1</i></b>-Negative Pregnant Women

<b><i>Background:</i></b> The clinical importance of assessing the fetal <i>KEL</i> genotype is to exclude ‘K'-positive fetuses (genotype <i>KEL1/KEL2</i>) in ‘K'-alloimmunized pregnant women (genotype <i>KEL2/KEL2</i>). Noninvasive assessment of the fetal <i>KEL</i> genotype is not yet available in the Czech Republic. <b><i>Objective:</i></b> The aim of this study was to assess the fetal <i>KEL1/KEL2</i> genotype from cell-free fetal DNA in the plasma of <i>KEL2/KEL2</i> pregnant women. <b><i>Methods:</i></b> The fetal genotype was assessed by minisequencing (a dilution series including control samples). A total of 138 pregnant women (between the 8th and 23rd gestational week) were tested by minisequencing. The fetal genotype was further verified by analysis of a buccal swab from the newborn. <b><i>Results:</i></b> Minisequencing proved to be a reliable method. In 2.2% (3/138) of the examined women, plasma sample testing failed; 94.8% (128/135) had the <i>KEL2/KEL2</i> genotype, and a total of 3.1% of fetuses (4/128) had the <i>KEL1/KEL2</i> genotype. Sensitivity and specificity reached 100% (p < 0.0001). <b><i>Conclusion:</i></b> Minisequencing is a reliable method for the assessment of the fetal <i>KEL1</i> allele from the plasma of <i>KEL2/KEL2</i> pregnant women.