Abstract
PurposeTo date, non-invasive prenatal diagnosis (NIPD) of monogenic disorders has been limited to cases with a paternal origin. This work shows a validation study of the Droplet Digital PCR (ddPCR) technology for analysis of both paternally and maternally inherited fetal alleles. For the purpose, single nucleotide polymorphisms (SNPs) were studied with the only intention to mimic monogenic disorders.MethodsNIPD SNP genotyping was performed by ddPCR in 55 maternal plasma samples. In 19 out of 55 cases, inheritance of the paternal allele was determined by presence/absence criteria. In the remaining 36, determination of the maternally inherited fetal allele was performed by relative mutation dosage (RMD) analysis.ResultsddPCR exhibited 100% accuracy for detection of paternal alleles. For diagnosis of fetal alleles with maternal origin by RMD analysis, the technology showed an accuracy of 96%. Twenty-nine out of 36 were correctly diagnosed. There was one FP and six maternal plasma samples that could not be diagnosed.DiscussionIn this study, ddPCR has shown to be capable to detect both paternal and maternal fetal alleles in maternal plasma. This represents a step forward towards the introduction of NIPD for all pregnancies independently of the parental origin of the disease.
Highlights
Monogenic diseases result from mutations in a single gene
The analysis of circulating cell-free fetal DNA in maternal blood [4] allows for non-invasive prenatal diagnosis (NIPD) of fetal genetic disorders to be performed somewhat more safely and without the need for a trained Obstetrician, since it only requires a venipuncture
Because of the coexistence of maternal and fetal DNA in the maternal plasma sample, NIPD approaches have been mainly limited to the study of paternally inherited or de novo alleles that are not present in the maternal genome, as the presence of these alleles in the maternal plasma ensures that they originated in the fetus and can be associated with the fetal genome, while absence of these alleles indicates a non-carrier fetus
Summary
NIPD SNP genotyping was performed by ddPCR in 55 maternal plasma samples. In 19 out of 55 cases, inheritance of the paternal allele was determined by presence/absence criteria. In the remaining 36, determination of the maternally inherited fetal allele was performed by relative mutation dosage (RMD) analysis
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