Chromosomal anomalies

Topic Completed: 1 February 2016

Revised: 30 April 2019

Copyright: 2002-2019,, Inc.

PubMed Search: Chromosomal anomalies [title] pediatric

Related: Trisomy 13, Trisomy 18, Trisomy 21

Elena Puscasiu, M.D.
Page views in 2019 to date: 26
Cite this page: Puscasiu E. Chromosomal anomalies. website. Accessed November 12th, 2019.
Definition / general
  • Chromosomal abnormalities represent the largest cause of conceptual loss
  • 6% of stillborns and 0.5% of liveborn infants have chromosomal abnormalities
  • Most embryos with chromosomal defects stop developing at ~4 weeks and abort spontaneously at 7 - 8 weeks
  • For abortuses that have reached a 2 week stage of development, the rate of chromosomal abnormalities is 78%; at 20 weeks, the rate is 62%
  • A high percentage (52%) of the chromosomal defects in the spontaneous abortion are autosomal trisomies
  • ~25% of liveborn infants with chromosomal abnormalities have autosomal trisomies, and ~40% have structural chromosomal defects
  • Trisomy 16 is the most common lethal trisomy
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