Noninvasive prenatal diagnosis by cell‐free DNA screening for fetomaternal HPA‐1a platelet incompatibility

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Abstract
BACKGROUND: The development of new noninvasive approaches for the diagnosis of human platelet antigen (HPA)‐1 fetomaternal incompatibility has become of great interest. These approaches allow determination of whether the fetus is incompatible or not with the mother and a decision on antenatal therapy to avoid fetal or neonatal alloimmune thrombocytopenia (FNAIT). The objective of this work was to perform rapid, noninvasive prenatal test for HPA‐1ab fetal antigen detection after the detection of an HPA‐1–homozygous mother by using plasma cell‐free DNA (cfDNA).STUDY DESIGN AND METHODS: The HPA‐1 genotypes of 142 pregnant women and 17 nonpregnant controls were retrospectively determined by high‐resolution melting (HRM) polymerase chain reaction (PCR). Coamplification at lower denaturation temperature (COLD) HRM PCR was performed to determine the fetal genotype analyzing cfDNA from all HPA‐1bb pregnant women.RESULTS: After the HRM analysis, the following genotypes were identified: HPA‐1aa (71.13%), HPA‐1bb (2.8%), and HPA‐1ab (26.06%). Four HPA‐1bb–homozygous pregnant women were carrying an incompatible fetus. Plasma samples from these mothers were analyzed by HRM COLD‐PCR. Homozygous HPA‐1bb pregnant women carrying an HPA‐1ab–heterozygous fetus did not group with either the HPA‐1ab or the HPA‐1bb controls. Thus, COLD‐PCR analysis allows the detection of HPA‐1ab–heterozygous fetuses carried by homozygous mothers during first weeks of pregnancy.CONCLUSION: The fetal genotype from HPA‐1bb–homozygous women was detected by a noninvasive prenatal test as soon as 12 weeks of gestation.
Funding Information
  • Fondo de Investigacion Sanitaria Instituto de Salud Carlos III (Red RETICEF RD06/00130001)