The utility of quantitative methylation assays at imprinted genes for the diagnosis of fetal and placental disorders

• Published in: Clinical genetics Vol. 79; no. 2; pp. 169 - 175
• Main Authors: Bourque, DK, Peñaherrera, MS, Yuen, RKC, Van Allen, MI, McFadden, DE, Robinson, WP
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01.02.2011; Wiley-Blackwell
• Subjects: 11p15.5; Biological and medical sciences; Birth defects; Chromosomes, Human, Pair 11 - genetics; Classical genetics, quantitative genetics, hybrids; DNA Methylation; Female; Fetal Diseases - diagnosis; Fetuses; Fundamental and applied biological sciences. Psychology; Gene expression; General aspects. Genetic counseling; Genes; Genetics of eukaryotes. Biological and molecular evolution; Genomic Imprinting; Human; Humans; imprinting; Indexing in process; KvDMR1; Medical diagnosis; Medical genetics; Medical sciences; Molecular and cellular biology; Molecular Diagnostic Techniques - methods; Placenta Diseases - diagnosis; Potassium Channels, Voltage-Gated - genetics; Pregnancy; Sequence Analysis, DNA - methods; triploidy; Human; imprinting; KvDMR1; Genomic imprinting; Assay; Placenta; DNA; DNA methylation; Fetus; Genetics; Diagnosis; Triploidy; Methylation; 11 p15.5; Quantitative analysis
• ISSN: 0009-9163; 1399-0004
• DOI: 10.1111/j.1399-0004.2010.01443.x

Bourque DK, Peñaherrera MS, Yuen RKC, Van Allen MI, McFadden DE, Robinson WP. The utility of quantitative methylation assays at imprinted genes for the diagnosis of fetal and placental disorders. An imbalance of imprinted gene expression within 11p15.5 is observed in Beckwith‐Wiedemann syndrome (BWS), as well as in a variety of placental abnormalities including complete hydatidiform mole (CHM), placental mesenchymal dysplasia (PMD) and triploidy. To facilitate the diagnosis of epigenetic errors and chromosomal imbalance of 11p15.5, we validated a pyrosequencing assay to measure methylation at KvDMR1 using blood samples from 13 BWS cases, 8 of which showed reduced methylation as compared to control blood. An imbalance between maternal and paternal genomes as is found in triploidy, CHM or PMD was also associated with altered KvDMR1 methylation. A reciprocal pattern of methylation was obtained in the triploid cases by assaying the proximal 11p15.5 ICR associated with H19. To distinguish chromosome 11 specific alterations from whole genome imbalance, other imprinted differentially methylated regions (DMRs) can be utilized. Thus, pyrosequencing assays for DMRs associated with SGCE, SNRPN, and MEST were also compared for their utility in diagnosing parental imbalance in placental samples. While each of these assays could successfully distinguish parental origin of triploidy, SGCE showed the clearest separation between groups. The combined use of a chromosome 11p15.5 assay (e.g. KvDMR1 or H19‐ICR) and non‐chromosome 11 assay (e.g. SGCE) provides a potentially valuable diagnostic tool in the rapid screening of methylation errors in placental disorders. These results also show the maintenance of imprinting status at these loci in the human placenta, even in the presence of abnormal pathology.