Background Phenylketonuria (PKU) is a common metabolic disorder caused predominately by mutations in the phenylalanine hydroxylase (PAH) gene. The aim of the study was to design and validate the performance of a non-invasive prenatal test (NIPT) for PKU using circulating single molecule amplification and resequencing technology (cSMART).
Methods A total of 18 couples at genetic risk for having a child with PKU were recruited to the study. Gold standard invasive prenatal diagnosis (IPD) was performed on amniocyte or villus cell DNA by Sanger sequencing, targeting the known parental PAH mutations. Retrospectively, NIPT was also performed on stored maternal plasma samples from the 18 pregnancies by a multiplex cSMART assay designed to target all known DNA variants in the PAH gene.
Results Benchmarking against IPD results, NIPT correctly genotyped all fetuses, including six compound heterozygotes with PKU, four normal non-carriers of PKU and eight heterozygote carriers of PKU comprising five cases of a maternally inherited mutation and three cases of a paternally inherited mutation.
Conclusions The NIPT cSMART PKU assay was highly sensitive and specific for mutation detection and correct assignment of fetal genotypes. Based on comprehensive mutation coverage across the PAH gene, the assay may initially have clinical utility as a pregnancy screening test for high-risk carrier couples.
- Phenylketonuria (pku)
- Noninvasive Prenatal Testing (nipt)
- Circulating Single Molecule Amplification And Re-sequencing Technology (csmart)
- Fetal Dna Fraction (ff)
- Fetal Genotyping
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Contributors XK conceived and designed the experiments. HD, NL and ZZ performed the experimental work. HD analysed the data and contributed to the writing of the manuscript. YL and YW developed the experimental plan and analysed the data. ZL performed bioinformatics analysis. MX collated the data, performed the final data analysis and designed the figures. DSC drafted and edited the manuscript for submission.
Funding This study was jointly funded by grants from the Henan province industrial– academic–research cooperation project (162107000017) and the National Natural Science Foundation of China (81672110 and 81701533).
Competing interests YL, YW, ZL, MX and DSC are employees of Berry Genomics Corporation. No one holds any stocks or bonds.
Ethics approval The clinical research study was conducted at the Genetics and Prenatal Diagnosis Center of the First Affiliated Hospital of Zhengzhou University with oversight from the Hospital Ethics Committee (approval number 2014–36).
Provenance and peer review Not commissioned; externally peer reviewed.
Data sharing statement Additional unpublished data from the study are available upon request from the corresponding author.