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Mosaicism

Part 1. Genetics

1.2. Cytogenetics

Short Specialist Review

  1. Wendy P. Robinson

Published Online: 15 OCT 2004

DOI: 10.1002/047001153X.g102313

Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics

Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics

How to Cite

Robinson, W. P. 2004. Mosaicism. Encyclopedia of Genetics, Genomics, Proteomics and Bioinformatics. 1:1.2:18.

Author Information

  1. University of British Columbia, Vancouver, BC, Canada

Publication History

  1. Published Online: 15 OCT 2004

Abstract

Chromosome mosaicism is observed in all types of human tissues, and can be a difficult finding to interpret in the genetics clinic. Prenatally diagnosed mosaicism is particularly challenging as the range of possible outcomes extends from normal to fetal malformation and/or in utero death, while there is little the clinician can do to assess the effects on in utero fetal development. As very low levels of abnormal cells may be “normal,” the interpretation of a mosaic finding needs to be carefully considered in terms of the patient phenotype, the type and origin of the abnormality, and the extent of abnormal cells. Microchimerism, which can for example occur through exchange of cells between mother and fetus, can also lead to genetically distinct cell types within an individual, and is gaining a reputation for being involved in a wide range of autoimmune conditions. Much further work is needed to understand the long-term effects of low-level mosaicism and microchimerism in humans.

Keywords:

  • mosaicism;
  • microchimerism;
  • trisomy;
  • prenatal diagnosis;
  • chimerism;
  • chromosomes