A preliminary evaluation study of new generation multiplex STR kits comprising of the CODIS core loci and the European Standard Set loci.

The GlobalFiler™ (Life Technologies), Investigator® 24plex QS (Qiagen), and PowerPlex® Fusion 6C (Promega) kits are the latest generation 6-dye fluorescent chemistry STR-PCR amplification kits. These kits allow for the simultaneous amplification of the CODIS core loci and the European Standard Set loci, as well as a few Y-STR loci in addition to the standard sex-determining marker Amelogenin. The present study was designed to be a preliminary evaluation of the three STR-PCR kits in terms of sensitivity, profile recovery from degraded DNA samples, tolerance to PCR inhibitors, and detection of minor components in DNA mixtures. The results showed that the three STR-PCR kits had relatively similar performance with each kit faring better for the different aspects studied. The PowerPlex® Fusion 6C and the Investigator® 24plex QS kits were shown to tolerate inhibitors better, while the GlobalFiler™ kit appeared to have a higher mean percentage recovery of alleles from low template DNA samples and for minor components in DNA mixtures.

Germline and somatic imprinting in the nonhuman primate highlights species differences in oocyte methylation.

Genomic imprinting is an epigenetic mechanism resulting in parental allele-specific gene expression. Defects in normal imprinting are found in cancer, assisted reproductive technologies, and several human syndromes. In mouse models, germline-derived DNA methylation is shown to regulate imprinting. Though imprinting is largely conserved between mammals, species- and tissue-specific domains of imprinted expression exist. Using the cynomolgus macaque (Macaca fascicularis) to assess primate-specific imprinting, we present a comprehensive view of tissue-specific imprinted expression and DNA methylation at established imprinted gene clusters. For example, like mouse and unlike human, macaque IGF2R is consistently imprinted, and the PLAGL1, INPP5F transcript variant 2, and PEG3 imprinting control regions are not methylated in the macaque germline but acquire this post-fertilization. Methylome data from human early embryos appear to support this finding. These suggest fundamental differences in imprinting control mechanisms between primate species and rodents at some imprinted domains, with implications for our understanding of the epigenetic programming process in humans and its influence on disease.

Epigenetic state and expression of imprinted genes in umbilical cord correlates with growth parameters in human pregnancy.

BACKGROUND: Genomic imprinting is a process causing genes to be expressed according to parental origin. Imprinting acts to coordinate fetal and prenatal growth, as well as control postnatal adaptations. Studies on human imprinting are confounded by tissue availability, sampling variability and limitations posed by tissue-specific expression and cellular heterogeneity within tissues. The human umbilical cord is an easily available, embryonic-derived fetal tissue with the potential to overcome many of these limitations. METHODS: In a sensitive, gene-specific quantitative expression analysis, we show for the first time robust imprinted gene expression combined with methylation analysis in cords isolated from Asian Chinese full-term births. RESULTS: Linear regression analyses revealed an inverse correlation between expression of pleckstrin homology-like domain, family A, member 2 (PHLDA2) with birth weight (BW). Furthermore, we observed significant down-regulation of the paternally expressed gene 10 (PEG10) in low BW babies compared to optimum BW babies. This change in PEG10 gene expression was accompanied by concomitant methylation alterations at the PEG10 promoter. CONCLUSIONS: These data are the first to demonstrate relative expression of an imprinted gene associated with epigenetic changes in non-syndromic fetal growth restriction in babies. They show that perturbed expression in compromised fetal growth may be associated with in utero modulation of the epigenetic state at the imprinting control regions and implicate specific imprinted genes as new biomarkers of fetal growth.