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Updated: Aug 17, 2025
Epigenetic Regulation of Cardiac Differentiation of Embryonic Stem Cells and Tissues
Published on: June 3, 2016
SNP and DNA methylation analyses of a monozygotic twins discordant for complete endocardial cushion defect: a case
Bihui Bao1, Hua Hu2, Limei Chen1
1Department of Obstetrics and Gynecology, Qingbaijiang Women's and Children's Hospital (Maternal and Child Health Hospital), West China Second University Hospital, Sichuan University Chengdu 610300, Sichuan, China.
Abstract:
The exact cause of complete endocardial cushion defect (ECD) is still unknown. This report describes a unique pair of monozygotic twins (MZ twins) discordant for ECD. The chromosome karyotyping analysis revealed normal karyotype of 46, XY, 16qh+ and mat in both MZ twins. A genome-wide analysis of DNA using the Affymetrix SNP 6.0 revealed identical genotyping of single nucleotide polymorphisms (SNPs) and copy number variations (CNVs). An extensive methylation assay was carried out by NimbleGen 3 × 720 K CpG Island Plus RefSeq Promoter Arrays to analyze the potential epigenetic differences. The DNA methylation profiles of the affected twin seemed increased compared with that of the unaffected twin. However, further validation of Notch1 promoter hypermethylation and six top-ranked differentially methylated CpG sites by sodium bisulfate modification and methylation-specific PCR, failed to reveal consistent methylation differences between the twins. Other relevant factors, such as heritability and penetrance of the condition that place the MZ twins near to a threshold for ECD or variations in local epigenetic events in the twins' heart tissues, are probably responsible for the phenotypic discordance.
