Mol. Hum. Reprod. Advance Access originally published online on June 24, 2008
Molecular Human Reproduction 2008 14(7):405-412; doi:10.1093/molehr/gan034
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CTG repeat instability in a human embryonic stem cell line carrying the myotonic dystrophy type 1 mutation
1Department of Embryology and Genetics, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium 2Centre for Medical Genetics, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium 3Centre for Reproductive Medicine, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium 4Laboratory for Experimental Surgery, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium 5Centre for Outcomes Research, Universitair Ziekenhuis Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium
6 Correspondence address. Centre for Medical Genetics, Vrije Universiteit Brussel, Laarbeeklaan 101, 1090 Brussels, Belgium. Tel: +32-24774635; Fax: +32-24778680; E-mail: karen.sermon{at}uzbrussel.be
Human embryonic stem cells (hESC) are considered to be an indefinite source of self-renewing cells that can differentiate into all types of cells of the human body and could be used in regenerative medicine, drug discovery and as a model for studying early developmental biology. hESC carrying disease-causing mutations hold promise as a tool to investigate mechanisms involved in the pathogenesis of the disease. In this report, we describe the behaviour of an expanded CTG repeat in the 3' untranslated region of the DMPK gene in VUB03_DM1, a hESC line carrying the myotonic dystrophy type 1 (DM1) mutation compared with the normal CTG repeat in two hESC lines VUB01 and VUB04_CF. Expanded CTG repeats were detected by small amount PCR, small pool PCR and Southern blot analysis in consecutive passages of VUB03_DM1. An important instability of the CTG repeat was detected during prolonged in vitro culture, showing stepwise increases of the repeat number in consecutive passages as well as a higher range of variability. This variability was present in cells of different colonies of the same passage and even within single colonies. The high repeat instability is in contrast to the previously observed stability of the repeat in preimplantation embryos and in fetuses during the first trimester of pregnancy. This in vitro culture of affected hESC represents a valuable model for studying the biology of repeat instability.
Key words: human embryonic stem cells/myotonic dystrophy type 1/DMPK/triplet repeat instability
Submitted on July 27, 2007; resubmitted on May 20, 2008; accepted on May 23, 2008.