Prenatal Screening for 22q11.2 Deletion Using a Targeted Microarray-Based Cell-Free DNA Test

Fetal Diagn Ther. 2018;44(4):299-304. doi: 10.1159/000484317. Epub 2017 Nov 8.


Objective: To determine the performance of a targeted microarray-based cell-free DNA (cfDNA) test (Harmony Prenatal Test®) for the identification of pregnancies at increased risk for 22q11.2 deletion.

Methods: Test performance was determined in 2 steps including a total of 1,953 plasma samples. Analytical validation was performed in 1,736 plasma samples. Clinical verification of performance was performed in an additional 217 prospectively ascertained samples from pregnancies with fetal deletion status determined by diagnostic testing.

Results: Analytical sensitivity was 75.4% (95% CI: 67.1-82.2%) based on 122 samples with deletions ranging from 1.96 to 3.25 Mb. In 1,614 presumed unaffected samples, specificity was determined to be at least 99.5% (95% CI: 99.0-99.7%). In the clinical cohort, 5 of 7 samples from pregnancies affected with 22q11.2 deletion were determined to have a high probability of deletion. There were no false positive results in the 210 unaffected samples in this cohort. These clinical data are consistent with the performance demonstrated in the analytical validation.

Conclusions: cfDNA testing using a targeted microarray-based technology is able to identify pregnancies at increased risk for 22q11.2 deletions of 3.0 Mb and smaller while maintaining a low false positive rate.

Keywords: 22q11.2 deletion; Cell-free DNA; Microdeletion; NIPT.

MeSH terms

  • Cell-Free Nucleic Acids
  • Chromosome Deletion*
  • Chromosomes, Human, Pair 22 / genetics*
  • Female
  • Genetic Testing / methods
  • Humans
  • Microarray Analysis / methods
  • Pregnancy
  • Prenatal Diagnosis / methods*


  • Cell-Free Nucleic Acids