Uniparental disomy (UPD) refers to a chromosome defect that an individual's homologous chromosome or segments are inherited from one parent. UPD can cause either aberrant patterns of genomic imprinting or homozygosity of mutations, leading to various diseases, including cancer. The mechanisms of UPD formation are diverse but largely due to the incorrect chromosome separation during cell division. UPD does not alter the number of gene copies, thus is difficult to be detected by conventional cytogenetic techniques effectively. Assisted by the new techniques such as single nucleotide polymorphism arrays, more and more UPD-related cases have been reported recently. UPD events are non-randomly distributed across cancer types, which play important role in the occurrence, development and metastasis of cancer. Here we review the research progress on the formation mechanisms, detection methods, the involved chromosomal regions and genes, and clinical significance of UPD; and also discuss the directions for future studies in this field.
Genomic Imprinting ; Humans ; Neoplasms ; genetics ; Research ; trends ; Uniparental Disomy

The overall prevalence of uniparental disomy (UPD) across all chromosomes was estimated to be around one birth in 2000. To date, more than 4170 UPD cases have been registered. UPD for chromosomes 6, 7, 11, 14, 15, and 20 can result in clinically recognizable imprinting disorders due to abnormal levels of imprinted gene expression. For other chromosomes, the clinical consequences associated with UPD are not apparent, unless when a recessive genetic disorder is unmasked by UPD or regions of homozygosity (ROH). A clinical practice guideline will assist in strengthening the precise analysis and interpretation of the clinical significance of ROH/UPD. This guideline summarizes the conception, mechanism and clinical consequences of ROH/UPD, as well as the principles for data analysis, with an aim to standardize the clinical application and data interpretation.
Gene Expression ; Genomic Imprinting ; Homozygote ; Humans ; Uniparental Disomy/genetics*

A subset of mammalian genes differ functionally between two alleles due to genomic imprinting, and seven such genes (Peg3, Usp29, APeg3, Zfp264, Zim1, Zim2, Zim3) are localized within the 500-kb genomic interval of the human and mouse genomes, constituting the Peg3 imprinted domain. This Peg3 domain shares several features with the other imprinted domains, including an evolutionarily conserved domain structure, along with transcriptional co-regulation through shared cis regulatory elements, as well as functional roles in controlling fetal growth rates and maternal-caring behaviors. The Peg3 domain also displays some unique features, including YY1-mediated regulation of transcription and imprinting; conversion and adaptation of several protein-coding members as ncRNA genes during evolution; and its close connection to human cancers through the potential tumor suppressor functions of Peg3 and Usp29. In this review, we summarize and discuss these features of the Peg3 domain.
Alleles ; Animals ; Fetal Development ; Genes, Tumor Suppressor ; Genome ; Genomic Imprinting ; Humans ; Mice ; YY1 Transcription Factor

PURPOSE: Whether parental origin of the intact X chromosome and/or the presence of Y chromosome sequences (Yseq) play a role in three-year height response to growth hormone (GH) were investigated. METHODS: Paternal (Xp) or maternal (Xm) origin of X chromosome was assessed by microsatellite marker analysis and the presence of hidden Yseq was analyzed. The first-, second-, and third-year GH response was measured as a change in height z-score (Z_Ht) in Turner syndrome (TS) patients with 45,Xp (n=10), 45,Xm (n=15), and 45,X/46,X,+mar(Y) (Xm_Yseq) (n=8). RESULTS: The mean baseline Z_Ht did not differ according to Xp or Xm origin, however the mean baseline Z_Ht was higher in the Xm_Yseq group than in Xm group, after adjusting for bone age delay and midparental Z_Ht (P=0.04). There was no difference in the height response to GH between the 3 groups. The height response to GH decreased progressively each year (P<0.001), such that the third-year increase in Z_Ht was not significant. This third-year decrease in treatment response was unaffected by Xp, Xm, and Xm_Yseq groups. Increasing GH dosage from the second to third-year of treatment positively correlated with the increase in Z_Ht (P=0.017). CONCLUSION: There was no evidence of X-linked imprinted genes and/or Yseq affecting height response to 3 years of GH therapy. Increasing GH dosages may help attenuate the decrease in third-year GH response in TS patients with 45,X and/or 46,X/+mar(Y).
Genomic Imprinting ; Growth Hormone* ; Humans ; Microsatellite Repeats ; Parents* ; Turner Syndrome* ; X Chromosome* ; Y Chromosome*

OBJECTIVETo construct a plasmid expressing human imprinted gene PEG10 and to study the effect of overexpression of PEG10 in a stable transfected human normal liver cell line L02 and in non-liver derived cell line 293.

METHODSFull length cDNA of PEG10 open reading frame 1 was amplified and subcloned into a mammalian expression vector pcDNA3.1hisC. Recombinant plasmid was stably transfected into L02 cells and control cells via Lipofectamine 2000. The expression and the function of PEG10 in L02 cells and control group cells were examined using RT-PCR, Western blot, MTT and TUNEL.

RESULTSRecombinant plasmid was successfully constructed and confirmed through DNA sequencing and restriction digesting. PEG10 gene accelerated the growth of L02 cells and inhibited their apoptosis but it had no conspicuous effect on the non-liver derived cells.

CONCLUSIONThe constructed expressing vector pcDNA3.1hisC-PEG10 provides a useful tool for further study on the effects and mechanisms of PEG10. Over-expression of PEG10 may promote L02 cells' proliferation and inhibit their apoptosis, but not in the non-liver derived cell line 293.

Cell Line ; Gene Expression ; Genetic Vectors ; Genomic Imprinting ; Humans ; Plasmids ; Proteins ; genetics ; Transfection

Erasure, establishment and maintenance of genetic imprinting are indispensable for normal embryonic development. All these processes depend on accurate expression and intimate cooperation of kinds of DNA methyltransferases. Many genetic syndromes and embryo developmental anomalies are caused by abnormality of genetic imprinting. Genetic imprinting is important for the nucleus totipotential of primordial germ cell, maturation of gamete,growth and development of embryo, structure and function of placenta as well as postnatal growth and development of individuals.
Animals ; DNA Methylation ; DNA Modification Methylases ; genetics ; metabolism ; Embryonic Development ; genetics ; Genomic Imprinting ; genetics ; Humans ; Mutation

Despite recent successes in cloning various mammals and amphibians, the low efficiency of animals production and abnormal symptoms in many cloned animals are crucial problems in cloning technology. To overcome these problems, scientists focus on mechanisms of cloning. A possible cause of the low success frequency of cloning is the insufficient dedifferentiation and the inadequate reprogramming of the high differentiated adult somatic nucleus in enucleated oocytes, which caused by incomplete methylation and premature de novo remethylation of donor DNA. In cloned embryos the methylation level is higher than normal embryos, and this may cause aberrant expression of several important genes, especially imprinting genes. Study on these mechanisms is very important to improve the rate of successful cloned animals.
Animals ; Cloning, Organism ; DNA Methylation ; genetics ; physiology ; Epigenesis, Genetic ; genetics ; physiology ; Genomic Imprinting ; genetics ; physiology ; Humans

Assisted reproduction technologies (ART) include controlled ovarian hyperstimulation, in vitro fertilization-embryo transfer, intracytoplasmic sperm injection, in vitro maturation of oocytes, pre-implantation genetic diagnosis, etc. They have been used for the treatment of impaired fertility but may damage the health of offspring. The ART procedures may alter the epigenetic status of these offspring and DNA methylation may be a crucial mechanism. This paper summarizes epigenetic alterations in ART embryos and offspring, and discusses the risks.
Animals ; DNA Methylation ; Embryo, Mammalian ; metabolism ; Female ; Fertilization in Vitro ; Genomic Imprinting ; Humans ; Pregnancy ; Preimplantation Diagnosis

OBJECTIVETo establish and improve the method of bisulfite sequencing for methylation status of imprinted genes in single human oocytes.

METHODSSingle superovulated immature human oocyte was embedded into low melting point agarose, followed by bisulfite treatment and polymerase chain reaction (PCR) amplification of the H19 and MEST genes. The PCR products were then subjected to TA cloning and sequencing to determine the methylation status.

RESULTSWith the modified methods of embedding and bisulfite treatment, we achieved a high PCR success rate of 82.46%, with the somatic cell contamination rate as low as 7.14%. The sequencing results showed no non-CpG cytosine and exact conformity to the theoretical sequences.

CONCLUSIONThe bisulfite sequencing method we used to determine the methylation status of imprinted genes at the single-cell level was highly efficient and reliable, which can serve as a foundation for the further study of the influences of human assisted reproductive technology on genomic imprinting.

DNA Methylation ; Female ; Genomic Imprinting ; genetics ; Humans ; Oocytes ; metabolism ; Polymerase Chain Reaction ; Sequence Analysis, DNA ; methods

Epigenetics comprises the modifications made in gene expressions without changing the DNA sequence itself. Significant epigenetic changes take place during spermatogenesis and fertilization and exert direct influences on embryogenesis. This article provides an overview of the latest researches on epigenetics of male germ cells and a brief discussion on the correlation of sperm with embryogenesis in four aspects: DNA methylation, histone modification, regulation of non-coding RNAs, and genomic imprinting.
Animals ; DNA Methylation ; Embryonic Development ; Epigenesis, Genetic ; Genomic Imprinting ; Histones ; metabolism ; Humans ; Male ; Spermatozoa