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Genes 2015, 6(2), 216-237;

Genetic Mosaics and the Germ Line Lineage

Department of Medicine, University of Montreal, Montreal, QC H3T 1C5, Canada
Centre de Recherche du CHU Ste-Justine, Montreal, QC H3T 1C5, Canada
Department of Medical Genetics, University of British Columbia, Vancouver, BC V6H 3N1, Canada
Author to whom correspondence should be addressed.
Academic Editor: J. Peter W. Young
Received: 24 February 2015 / Revised: 27 March 2015 / Accepted: 7 April 2015 / Published: 17 April 2015
(This article belongs to the Section Human Genomics and Genetic Diseases)
Full-Text   |   PDF [681 KB, uploaded 17 April 2015]   |  


Genetic mosaics provide information about cellular lineages that is otherwise difficult to obtain, especially in humans. De novo mutations act as cell markers, allowing the tracing of developmental trajectories of all descendants of the cell in which the new mutation arises. De novo mutations may arise at any time during development but are relatively rare. They have usually been observed through medical ascertainment, when the mutation causes unusual clinical signs or symptoms. Mutational events can include aneuploidies, large chromosomal rearrangements, copy number variants, or point mutations. In this review we focus primarily on the analysis of point mutations and their utility in addressing questions of germ line versus somatic lineages. Genetic mosaics demonstrate that the germ line and soma diverge early in development, since there are many examples of combined somatic and germ line mosaicism for de novo mutations. The occurrence of simultaneous mosaicism in both the germ line and soma also shows that the germ line is not strictly clonal but arises from at least two, and possibly multiple, cells in the embryo with different ancestries. Whole genome or exome DNA sequencing technologies promise to expand the range of studies of genetic mosaics, as de novo mutations can now be identified through sequencing alone in the absence of a medical ascertainment. These technologies have been used to study mutation patterns in nuclear families and in monozygotic twins, and in animal model developmental studies, but not yet for extensive cell lineage studies in humans. View Full-Text
Keywords: mosaicism; germ line; lineage; de novo mutation mosaicism; germ line; lineage; de novo mutation

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This is an open access article distributed under the Creative Commons Attribution License which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. (CC BY 4.0).

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Samuels, M.E.; Friedman, J.M. Genetic Mosaics and the Germ Line Lineage. Genes 2015, 6, 216-237.

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