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Related Concept Videos

Meiosis vs. Mitosis02:57

Meiosis vs. Mitosis

Cell division is necessary for growth and reproduction in organisms. Mitosis aids cell growth and development by dividing somatic cells. In contrast, meiosis causes the division of germ cells and plays an essential role in sexual reproduction. Due to their unique functional requirements, mitosis and meiosis differ from each other in multiple aspects.
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In Vitro Modeling of Down Syndrome Neurogenesis Using Human-Induced Pluripotent Stem Cells
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In Vitro Modeling of Down Syndrome Neurogenesis Using Human-Induced Pluripotent Stem Cells

Published on: March 7, 2025

Second trimester serum tests for Down's Syndrome screening.

S Kate Alldred1, Jonathan J Deeks, Boliang Guo

  • 1Department of Women’s and Children’s Health, The University of Liverpool, Liverpool, UK. k.alldred@liv.ac.uk.

The Cochrane Database of Systematic Reviews
|June 15, 2012
PubMed
Summary
This summary is machine-generated.

Second-trimester screening for Down

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Semiconductor Sequencing for Preimplantation Genetic Testing for Aneuploidy

Published on: August 25, 2019

Area of Science:

  • Prenatal diagnostics
  • Biochemical screening
  • Maternal serum analysis

Background:

  • Down's syndrome is a genetic condition caused by an extra copy of chromosome 21.
  • It is the most common congenital cause of intellectual disability.
  • Noninvasive screening methods aid in assessing pregnancy risk and guiding further testing.

Purpose of the Study:

  • To evaluate and compare the diagnostic accuracy of second-trimester maternal serum markers for Down's syndrome detection.
  • To assess the performance of various marker combinations and the influence of maternal age.

Main Methods:

  • A comprehensive literature search was conducted across multiple databases (MEDLINE, EMBASE, etc.) from 1980 to 2007.
  • Studies included maternal serum tests in women aged 14-24 weeks gestation, with Down's syndrome confirmed by chromosomal analysis or postnatal inspection.
  • Hierarchical summary ROC meta-analysis was used to analyze test performance, sensitivity, and specificity, with subgroup analyses for maternal age.

Main Results:

  • Meta-analysis of 59 studies (341,261 pregnancies) revealed that double and triple marker tests (AFP, uE3, hCG, free βhCG) detect 60-70% of Down's syndrome cases with a 5% false positive rate.
  • Tests including inhibin showed higher detection rates (80%) but were not significantly better than triple tests in direct comparisons.
  • Test sensitivity was lower in women over 35, with differential verification bias impacting accuracy.

Conclusions:

  • Combined maternal serum markers (two or more) with maternal age significantly improve Down's syndrome detection sensitivity over single markers.
  • The benefit of using four or more markers or including inhibin has not been statistically proven.
  • Further research is needed on reduced test performance in older women and the impact of pregnancy loss on screening accuracy.