María Serena Peñaherrera

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Haplotype analysis was undertaken in 20 cases of 15q11-q13 deletion associated with Prader-Willi syndrome (PWS) or Angelman syndrome (AS) to determine if these deletions arose through unequal meiotic crossing over between homologous chromosomes. Of these, six cases of PWS and three of AS were informative for markers on both sides of the deletion. For four(More)
The human placenta facilitates the exchange of nutrients, gas and waste between the fetal and maternal circulations. It also protects the fetus from the maternal immune response. Due to its role at the feto-maternal interface, the placenta is subject to many environmental exposures that can potentially alter its epigenetic profile. Previous studies have(More)
UNLABELLED Many genes exhibiting genomic imprinting, parent-of-origin differences in gene expression, are involved in regulating placental and fetal growth. The goal of the present study was to assess whether abnormal regulation of imprinted genes is associated with intrauterine growth restriction (IUGR) and/or preeclampsia (PET). METHODS Genomic DNA was(More)
Preeclampsia and intrauterine growth restriction (IUGR) are two of the most common adverse pregnancy outcomes, but their underlying causes are mostly unknown. Although multiple studies have investigated gene expression changes in these disorders, few studies have examined epigenetic changes. Analysis of the DNA methylation pattern associated with such(More)
Interindividual variation in DNA-methylation level is widespread in the human genome, despite its critical role in regulating gene expression. The nature of this variation, including its tissue-specific nature, and the role it may play in human phenotypic variation and disease is still poorly characterized. The placenta plays a critical role in regulating(More)
UNLABELLED Obtaining representative samples from a term placenta for gene-expression studies is confounded by both within placental heterogeneity and sampling effects such as sample location and processing time. Epigenetic processes involved in the regulation of gene expression, such as DNA methylation, may show similar variability, but are less well(More)
Paternal uniparental disomy (UPD) for chromosome 15 (UPD15), which is found in approximately 2% of Angelman syndrome (AS) patients, is much less frequent than maternal UPD15, which is found in 25% of Prader-Willi syndrome patients. Such a difference cannot be easily accounted for if 'gamete complementation' is the main mechanism leading to UPD. If we assume(More)
Non-random X-chromosome inactivation (XCI) has been associated with X-linked diseases, neoplastic diseases, recurrent pregnancy loss, and trisomy risk. It also occurs more commonly in older female populations. To understand the etiology of non-random XCI and utilize this assay appropriately in clinical research and practice, the age-related alteration in(More)
An increase in extremely skewed X-chromosome inactivation (XCI) (> or = 90%) among women who experienced recurrent spontaneous abortion (RSA) has been previously reported. To further delineate the etiology of this association, we have evaluated XCI status in 207 women who experience RSA. A significant excess of trisomic losses was observed among the women(More)