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Ultrasound Obstet Gynecol. 2016 Feb;47(2):177-83. doi: 10.1002/uog.15754. Epub 2016 Jan 5.

Clinical experience with single-nucleotide polymorphism-based non-invasive prenatal screening for 22q11.2 deletion syndrome.

Author information

1
Natera Inc, San Carlos, CA, USA.
2
Division of Human Genetics, The Children's Hospital of Philadelphia, Perelman School of Medicine at the University of Pennsylvania, Philadelphia, PA, USA.
3
Clinical Genetics Research Program, Centre for Addiction and Mental Health, Toronto, Ontario, Canada.
4
Division of Human Genetics, Department of Genetics and Genome Sciences, University of Connecticut Health Center, Farmington, CT, USA.

Abstract

OBJECTIVES:

To evaluate the performance of a single-nucleotide polymorphism (SNP)-based non-invasive prenatal test (NIPT) for the detection of fetal 22q11.2 deletion syndrome in clinical practice, assess clinical follow-up and review patient choices for women with high-risk results.

METHODS:

In this study, 21 948 samples were submitted for screening for 22q11.2 deletion syndrome using a SNP-based NIPT and subsequently evaluated. Follow-up was conducted for all cases with a high-risk result.

RESULTS:

Ninety-five cases were reported as high risk for fetal 22q11.2 deletion. Diagnostic testing results were available for 61 (64.2%) cases, which confirmed 11 (18.0%) true positives and identified 50 (82.0%) false positives, resulting in a positive predictive value (PPV) of 18.0%. Information regarding invasive testing was available for 84 (88.4%) high-risk cases: 57.1% (48/84) had invasive testing and 42.9% (36/84) did not. Ultrasound anomalies were present in 81.8% of true-positive and 18.0% of false-positive cases. Two additional cases were high risk for a maternal 22q11.2 deletion; one was confirmed by diagnostic testing and one had a positive family history. There were three pregnancy terminations related to screening results of 22q11.2 deletion, two of which were confirmed as true positive by invasive testing.

CONCLUSIONS:

Clinical experience with this SNP-based non-invasive screening test for 22q11.2 deletion syndrome indicates that these deletions have a frequency of approximately 1 in 1000 in the referral population with most identifiable through this test. Use of this screening method requires the availability of counseling and other management resources for high-risk pregnancies.

KEYWORDS:

22q11.2 deletion syndrome; NIPT; cardiac defects; microdeletions; ultrasound

PMID:
26396068
PMCID:
PMC5064640
DOI:
10.1002/uog.15754
[Indexed for MEDLINE]

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