Clinical Significance of Non-Invasive Prenatal Screening for Trisomy 7: Cohort Study and Literature Review

Genes (Basel). 2020 Dec 24;12(1):11. doi: 10.3390/genes12010011.


Trisomy 7 is the most frequently observed type of rare autosomal trisomies in genome-wide non-invasive prenatal screening (NIPS). Currently, the clinical significance of trisomy 7 NIPS-positive results is still unknown. We reviewed two independent cohorts from two laboratories where similar NIPS metrics were applied. A total of 70,441 singleton cases who underwent genome-wide NIPS were analyzed, among which 39 pregnancies were positive for trisomy 7, yielding a screen-positive rate of 0.055% (39/70,441). There were 28 cases with invasive testing results available; the positive predictive value (PPV) was 3.6% (1/28). We then searched the published NIPS studies to generate a large cohort of 437,873 pregnancies and identified 247 cases (0.056%) that were screened positive for trisomy 7. The overall PPV was 3.4% (4/118) in the combined data. The presence of uniparental disomy 7 was not detected in the NIPS trisomy 7-positive pregnancies with normal fetal karyotype. Among the 85 cases with pregnancy outcome available in combined data, 88.2% were normal live births, 14.1% had intrauterine growth restriction, preterm birth or low birth weight, 3.5% presented with ultrasound abnormality, and no fetal loss was observed. Our data provide valuable information for counseling and management of trisomy 7-positive NIPS pregnancies.

Keywords: cell-free DNA screening; cell-free fetal DNA; non-invasive prenatal screening; trisomy 7; uniparental disomy 7.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Adult
  • Cell-Free Nucleic Acids / blood
  • Cell-Free Nucleic Acids / genetics
  • Chromosomes, Human, Pair 7 / genetics*
  • Female
  • Fetal Growth Retardation / epidemiology
  • Fetal Growth Retardation / genetics
  • Fetal Growth Retardation / prevention & control*
  • Humans
  • Karyotyping / methods
  • Live Birth / epidemiology
  • Maternal Age
  • Middle Aged
  • Noninvasive Prenatal Testing / methods*
  • Predictive Value of Tests
  • Pregnancy
  • Premature Birth / epidemiology
  • Premature Birth / genetics
  • Premature Birth / prevention & control*
  • Retrospective Studies
  • Trisomy / genetics*
  • Young Adult


  • Cell-Free Nucleic Acids