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The critical region, critical value, and significance level are interdependent concepts crucial in hypothesis testing.
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Non-invasive prenatal aneuploidy testing: Critical diagnostic performance parameters predict sample z-score values.

Jonatan Blais1, Sylvie Giroux2, André Caron2

  • 1Service of Medical Biochemistry, Department of Medical Biology, CHU de Québec - Université Laval, Quebec, Canada; Department of Molecular Biology, Medical Biochemistry, and Pathology, Faculty of Medicine, Université Laval, Quebec, Canada; Human and Molecular Genetics Research Unit, Research Center, CHU de Québec, Quebec, Canada.

Clinical Biochemistry
|July 1, 2018
PubMed
Summary

Non-invasive prenatal testing (NIPT) performance depends heavily on fetal DNA fraction (FF) and chromosomal ratio (chr_ratio) variation. Understanding these factors is crucial for accurate aneuploidy detection in clinical settings.

Keywords:
Down syndromeFetal DNANIPTNext-generation sequencingNon-invasive prenatal testingcffDNA

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Area of Science:

  • Genetics and Genomics
  • Molecular Diagnostics
  • Prenatal Screening

Background:

  • Non-invasive prenatal testing (NIPT) uses cell-free DNA in maternal plasma to screen for chromosomal aneuploidies.
  • Current NIPT relies on chromosomal ratio (chr_ratio) measurements, with performance known to be influenced by fetal DNA fraction (FF).

Purpose of the Study:

  • To quantitatively assess the impact of fetal DNA fraction (FF) and chr_ratio measurement variability on NIPT diagnostic performance.
  • To validate theoretical models with empirical data from multiple NIPT assays.

Main Methods:

  • Theoretical modeling of relationships between FF, chr_ratio coefficient of variation (CV), and diagnostic performance metrics (specificity, PPV).
  • Empirical validation using data from three distinct NIPT assays.

Main Results:

  • Specificity and positive predictive values (PPV) demonstrated significant sensitivity to changes in FF and chr_ratio CV.
  • Theoretical predictions of chr_ratio z-scores closely matched observed values, confirming the critical influence of FF and chr_ratio CV.
  • Small variations in FF and chr_ratio CV substantially impact NIPT accuracy.

Conclusions:

  • Accurate NIPT assay evaluation necessitates understanding the FF distribution within the target population.
  • Precise measurement of chr_ratio CV for specific chromosomes/regions is essential for reliable NIPT results.
  • Laboratories must meticulously quantify FF and chr_ratio CV to ensure test reliability and clinical utility.