Non-invasive prenatal chromosomal aneuploidy testing--clinical experience: 100,000 clinical samples.

OBJECTIVE: As the first laboratory to offer massively parallel sequencing-based noninvasive prenatal testing (NIPT) for fetal aneuploidies, Sequenom Laboratories has been able to collect the largest clinical population experience data to date, including >100,000 clinical samples from all 50 U.S. states and 13 other countries. The objective of this study is to give a robust clinical picture of the current laboratory performance of the MaterniT21 PLUS LDT. STUDY DESIGN: The study includes plasma samples collected from patients with high-risk pregnancies in our CLIA-licensed, CAP-accredited laboratory between August 2012 to June 2013. Samples were assessed for trisomies 13, 18, 21 and for the presence of chromosome Y-specific DNA. Sample data and ad hoc outcome information provided by the clinician was compiled and reviewed to determine the characteristics of this patient population, as well as estimate the assay performance in a clinical setting. RESULTS: NIPT patients most commonly undergo testing at an average of 15 weeks, 3 days gestation; and average 35.1 years of age. The average turnaround time is 4.54 business days and an overall 1.3% not reportable rate. The positivity rate for Trisomy 21 was 1.51%, followed by 0.45% and 0.21% rate for Trisomies 18 and 13, respectively. NIPT positivity rates are similar to previous large clinical studies of aneuploidy in women of maternal age ≥ 35 undergoing amniocentesis. In this population 3519 patients had multifetal gestations (3.5%) with 2.61% yielding a positive NIPT result. CONCLUSION: NIPT has been commercially offered for just over 2 years and the clinical use by patients and clinicians has increased significantly. The risks associated with invasive testing have been substantially reduced by providing another assessment of aneuploidy status in high-risk patients. The accuracy and NIPT assay positivity rate are as predicted by clinical validations and the test demonstrates improvement in the current standard of care

Evaluation of a novel screening method for fetal aneuploidy using cell-free DNA in maternal plasma

Objective: To evaluate the test performance of a novel sequencing technology using molecular inversion probes applied to cell-free DNA screening for fetal aneuploidy. Methods: Two cohorts were included in the evaluation; a risk-based cohort of women receiving diagnostic testing in the first and second trimesters was combined with stored samples from pregnancies with fetuses known to be aneuploid or euploid. All samples were blinded to testing personnel before being analyzed, and validation occurred after the study closed and results were merged. Results: Using the new sequencing technology, 1414 samples were analyzed. The findings showed sensitivities and specificities for the common trisomies and the sex chromosome aneuploidies at >99% (Trisomy 21 sensitivity 99.2 CI 95.6-99.2; specificity 99.9 CI 99.6-99.9). Positive predictive values among the trisomies varied from 85.2% (Trisomy 18) to 99.0% (Trisomy 21), reflecting their prevalence rates in the study. Comparisons with a meta-analysis of recent cell-free DNA screening publications demonstrated equivalent test performance. Conclusion: This new technology demonstrates equivalent test performance compared with alternative sequencing approaches, and demonstrates that each chromosome can be successfully interrogated using a single probe

Breakdown of the NIPT Final Results.

<p>Trisomy 13 and 18 began reporting in February 2012.</p><p>Breakdown of the NIPT Final Results.</p

NIPT T21 Modeled Performance at Low Fetal Fractions.

<p>In figure, 27,824 samples that passed all laboratory quality criteria with fetal fractions between 4 and 8% were fitted into two normal distributions, one for euploids and one for T21 positives. The fitted distribution was used to estimate specificity and sensitivity.</p

NIPT Laboratory Performance.

<p>The table shows key laboratory performance indicators. Business days are defined as Monday through Friday excluding federal holidays. Canceled tests are samples that are inappropriate for testing primarily those with no indication for testing. Amended reports primarily include reports amended for typographical errors.</p><p>NIPT Laboratory Performance.</p

Impact of BMI on Final Results.

<p>This figure shows a breakdown of final results when binned by maternal BMI. The number of patients in each bin is displayed above their respective bin.</p

Average NIPT Patient Demographics (n = 100,000).

<p>Gestational age was determined by LMP or ultrasound. Maternal height and weight are not required for testing and not provided for all samples, n = 86,734.</p><p>Average NIPT Patient Demographics (n = 100,000).</p