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Noninvasive detection of fetal subchromosomal abnormalities by semiconductor sequencing of maternal plasma DNA

  1. Kang Zhange,g,i,2
  1. aPrenatal Diagnosis Centre, Guangdong Women and Children Hospital, Guangzhou 510010, China;
  2. bMaternal and Children Metabolic-Genetic Key Laboratory, Guangdong Women and Children Hospital, Guangzhou 510010, China;
  3. cGuangdong Thalassemia Diagnostic Centre, Guangzhou 510010, China;
  4. dCapitalBio Genomics Co., Ltd., Dongguan 523808, China;
  5. eInstitute for Genomic Medicine and Shiley Eye Institute, University of California, San Diego, La Jolla, CA 92328;
  6. fKangrui Biological Pharmaceutical Technology Co., Ltd., Guangzhou 510005, China;
  7. gMolecular Medicine Research Center, State Key Laboratory of Biotherapy, West China Hospital and Sichuan University, Chengdu 610041, China;
  8. hDepartment of Pharmacology, University of California, San Diego, La Jolla, CA 92328;
  9. iVeterans Administration Healthcare System, San Diego, CA 92161

  1. Contributed by Michael Karin, September 28, 2015 (sent for review June 3, 2015)

Significance

Noninvasive prenatal testing (NIPT) using sequencing of fetal cell-free DNA from maternal plasma has allowed accurate prenatal diagnosis of aneuploidy without requirement of an invasive procedure; this approach has gained increasing clinical acceptance. In this manuscript, we evaluate whether NIPT using semiconductor sequencing platform (SSP) could reliably detect subchromosomal deletions/duplications in women carrying a high-risk fetus. We show that detection of fetal subchromosomal abnormalities is a viable extension of NIPT using SSP. Given the recent strong interest in NIPT using cell-free DNA, these results should be of broad interest and immediate clinical importance, even beyond the NIPT field, such as for detection of cell-free tumor DNA.

Abstract

Noninvasive prenatal testing (NIPT) using sequencing of fetal cell-free DNA from maternal plasma has enabled accurate prenatal diagnosis of aneuploidy and become increasingly accepted in clinical practice. We investigated whether NIPT using semiconductor sequencing platform (SSP) could reliably detect subchromosomal deletions/duplications in women carrying high-risk fetuses. We first showed that increasing concentration of abnormal DNA and sequencing depth improved detection. Subsequently, we analyzed plasma from 1,456 pregnant women to develop a method for estimating fetal DNA concentration based on the size distribution of DNA fragments. Finally, we collected plasma from 1,476 pregnant women with fetal structural abnormalities detected on ultrasound who also underwent an invasive diagnostic procedure. We used SSP of maternal plasma DNA to detect subchromosomal abnormalities and validated our results with array comparative genomic hybridization (aCGH). With 3.5 million reads, SSP detected 56 of 78 (71.8%) subchromosomal abnormalities detected by aCGH. With increased sequencing depth up to 10 million reads and restriction of the size of abnormalities to more than 1 Mb, sensitivity improved to 69 of 73 (94.5%). Of 55 false-positive samples, 35 were caused by deletions/duplications present in maternal DNA, indicating the necessity of a validation test to exclude maternal karyotype abnormalities. This study shows that detection of fetal subchromosomal abnormalities is a viable extension of NIPT based on SSP. Although we focused on the application of cell-free DNA sequencing for NIPT, we believe that this method has broader applications for genetic diagnosis, such as analysis of circulating tumor DNA for detection of cancer.

Footnotes

  • ↵1A.-h.Y., C.-f.P., and X.Z. contributed equally to this work.

  • ↵2To whom correspondence may be addressed. Email: yinaiwa{at}vip.126.com, qfhuang{at}capitalgenomics.com, mkarin{at}ucsd.edu, or kang.zhang{at}gmail.com.

  • Author contributions: A.-h.Y., Q.-f.H., M. Karin, and K.Z. designed research; C.-f.P., X.Z., J.-x.Y., J.L., W.-w.H., C.L., D.-h.L., J.W., R.Q.X., M.-q.M., F.-f.G., Y.-m.Q., D.-m.W., and Y.-n.W. performed research; C.-f.P., H.-l.L., and Y.-y.C. contributed new reagents/analytic tools; A.-h.Y., B.A.C., H.-l.L., R.H., M.Z., M.A., L.Z., M. Krawczyk, D.Z., and K.Z. analyzed data; and A.-h.Y., B.A.C., H.-l.L., M. Karin, and K.Z. wrote the paper.

  • The authors declare no conflict of interest.

  • This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/pnas.1518151112/-/DCSupplemental.

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