CTG repeat instability in a human embryonic stem cell line carrying the myotonic dystrophy type 1 mutation.

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.

Methylation analysis of the intergenic differentially methylated region of DLK1-GTL2 in human.

Imprinting is a non-Mendelian form of inheritance where epigenetic modifications control mono-allelic expression depending on the parental origin. Methylation of CpG-dinucleotides at differentially methylated regions (DMRs) is one of the best-studied mechanisms directing expression to one specific parental allele. We studied the methylation patterns of the intergenic (IG)-DMR of DLK1 and GTL2.

Derivation of human embryonic stem cell lines from embryos obtained after IVF and after PGD for monogenic disorders.

Background: Human embryonic stem (hES) cells are pluripotent cells usually derived from the inner cell mass (ICM) of blastocysts. Because of their ability to differentiate into all three embryonic germ layers, hES cells represent an important material for studying developmental biology and cell replacement therapy. hES cell lines derived from blastocysts diagnosed as carrying a genetic disorder after PGD represent in vitro disease models.

Intergenerational instability of the expanded CTG repeat in the DMPK gene: studies in human gametes and preimplantation embryos.

The CTG repeat at the 3' untranslated region of the dystrophia myotonica protein kinase (DMPK) gene shows marked intergenerational and somatic instability in patients with myotonic dystrophy (DM1), when the repeat is expanded to more than approximately 55 repeats. Intensive research has yielded some insights into the timing and mechanism of these intergenerational changes: (1) increases in expansion sizes occur during gametogenesis but probably not during meiosis, (2) the marked somatic mosaicism becomes apparent from the 2nd trimester of development onward and increases during adult life, and (3) DNA repair mechanisms are involved. We have performed preimplantation genetic diagnosis for DM1 since 1995, which has given us the unique opportunity to study the expanded CTG repeat in affected embryos and in gametes from affected patients.