Long non-coding RNAs (lncRNAs) reportedly function as important modulators of gene regulation and malignant processes in the development of human cancers. The lncRNA JPX is a novel molecular switch for X chromosome inactivation and differentially expressed JPX has exhibited certain clinical correlations in several cancers. Notably, JPX participates in cancer growth, metastasis, and chemoresistance, by acting as a competing endogenous RNA for microRNA, interacting with proteins, and regulating some specific signaling pathways. Moreover, JPX may serve as a potential biomarker and therapeutic target for the diagnosis, prognosis, and treatment of cancer. The present article summarizes our current understanding of the structure, expression, and function of JPX in malignant cancer processes and discusses its molecular mechanisms and potential applications in cancer biology and medicine.
Humans ; RNA, Long Noncoding/genetics* ; Neoplasms/genetics* ; MicroRNAs/genetics* ; Gene Expression Regulation ; X Chromosome Inactivation

OBJECTIVETo explore the pathogenetic mechanism for a female patient affected with hemophilia A (HA).

METHODSPotential genetic defect was detected with inverse shifting-polymerase chain reaction (IS-PCR). The pattern of X chromosome inactivation was determined with a human androgen receptor assay (HUMARA assay). G-banded karyotyping was carried out to exclude potential chromosome aberrations.

RESULTSIS-PCR showed that the defect of FVIII gene was the distal type of intron 22 inversion. The HUMARA assay showed that the X chromosome inactivation was non-random, and that the mother's X chromosome activity was lower than that of the father's X chromosome which has carried the inverted FVIII gene. No abnormalities were found with G-banded chromosomes.

CONCLUSIONThe prevalence of female HA patient may be caused by non-random inactivation of X chromosomes.

Adolescent ; Female ; Hemophilia A ; etiology ; genetics ; Humans ; Karyotyping ; Polymerase Chain Reaction ; Receptors, Androgen ; analysis ; X Chromosome Inactivation

OBJECTIVE: The XIST gene is considered to be an attractive candidate gene for skewed X-chromosome inactivation and a possible cause of primary ovarian insufficiency (POI). The purpose of this study was to investigate whether the XIST gene promoter mutation is associated with idiopathic POI in a sample of the Korean population. METHODS: Subjects consisted of 102 idiopathic POI patients and 113 healthy controls with normal menstrual cycles. Patients with the following known causes of POI were excluded in advance: cytogenetic abnormalities, prior chemo- or radiotherapy, or prior bilateral oophorectomy. Genotyping was performed using polymerase chain reaction-restriction fragment length polymorphism analysis. RESULTS: The mean age of onset of ovarian insufficiency was 28.7+/-8.5 years and the mean values of serum luteinizing and follicle-stimulating hormones and estradiol in the POI group were 31.4+/-18.2 mIU/mL, 74.5+/-41.1 mIU/mL, and 30.5+/-36.7 pg/mL, respectively. We found no cytosine to guanine (C43G) variation in the XIST gene in both POI patients and controls. CONCLUSION: The C43G mutation in the promoter region of the XIST gene was not present in the Korean patients with idiopathic POI in our study, in contrast to our expectation, suggesting that the role of XIST in the pathogenesis of POI is not yet clear.
Age of Onset ; Chromosome Aberrations ; Cytosine ; Estradiol ; Female ; Guanine ; Humans ; Lutein ; Menstrual Cycle ; Ovariectomy ; Primary Ovarian Insufficiency* ; Promoter Regions, Genetic* ; Radiotherapy ; X Chromosome Inactivation

OBJECTIVETo investigate whether the four boys with delayed motor development and intellectual disability suffer from MECP 2 duplication syndrome.

METHODBlood specimens and clinical data of four patients and mothers of patient 2 and patient 4 were collected. Genomic DNA was extracted from peripheral blood using DNA extraction kit. At first multiplex ligation-dependent probe amplification (MLPA) was employed in 4 patients, two distinct kits SALSA P036 and P070 for sub-telomere screening, and SALSA P245 for the 22 common microdeletion and microduplication syndromes. Then array-CGH analysis was carried out. Two mothers of patients were tested by array- comparative genomic hybridization (CGH) and X chromosome inactivation analysis.

RESULTAll the 4 patients presented with severe hypotonia, delayed motor development, intellectual disability and absent or limited language. Three patients manifested recurrent pneumonia in infancy except patient 2. Four patients had duplication on chromosome Xq28 with MLPA kit SALSA P245. Array-CGH identified the size of each duplication on Xq28. The precise size of each duplication was different in the four patients: patient 1, 14.931 Mb, patient 2, 0.393 Mb, patient 3, 0.482 Mb and patient 4, 0.299 Mb. To compare Xq28 duplications with UCSC database (http://genome.ucsc.edu/) revealed that each duplication harbors the MECP 2 and HCFC 1 gene. Mothers of patient 2 and patient 4 also carried microduplication on Xq28. X chromosome inactivation analysis demonstrated completely skewed inactivation (0: 100) and it is the inactive allele that passed on to the patients.

CONCLUSIONFor patients that present with delayed motor development, intellectual disability, hypotonia, absent or limited language and recurrent infection, combination of MLPA and array- CGH is effective and specific diagnostic methods of MECP 2 duplication syndrome.

Chromosomes, Human, X ; genetics ; Comparative Genomic Hybridization ; Gene Duplication ; Humans ; Male ; Mental Retardation, X-Linked ; diagnosis ; genetics ; Methyl-CpG-Binding Protein 2 ; genetics ; Multiplex Polymerase Chain Reaction ; X Chromosome Inactivation

A 31-year-old woman, who was pregnant with twins, underwent chorionic villus sampling because of increased nuchal translucency in one of the fetuses. Cytogenetic analysis showed a normal karyotype in the fetus with increased nuchal translucency. However, the other fetus, with normal nuchal translucency, had a derivative X chromosome (der(X)). For further analysis, fluorescence in situ hybridization (FISH) and additional molecular studies including fragile X analysis were performed. FISH analysis confirmed that the Y chromosome was the origin of extra segment of the der(X). The X-chromosome breakpoint was determined to be at Xq27 by FMR1 CGG repeat analysis, and the Y-chromosome breakpoint was determined to be at Yq11.23 by the Y chromosome microdeletion study. To predict the fetal outcome, the X-inactivation pattern was examined, and it revealed non-random X inactivation of the der(X). To the best of our knowledge, the identification of an unbalanced Xq;Yq translocation at prenatal diagnosis has never been reported. This study was performed to identify precise breakpoints and the X-inactivation pattern as well as to provide the parents with appropriate genetic counseling.
Adult ; Chorionic Villi Sampling ; Cytogenetic Analysis ; Female ; Fetus* ; Fluorescence ; Genetic Counseling ; Humans ; In Situ Hybridization ; Karyotype ; Nuchal Translucency Measurement ; Parents ; Pregnancy ; Prenatal Diagnosis ; Twins ; X Chromosome ; X Chromosome Inactivation ; Y Chromosome

Hemophilia is a relatively rare bleeding disorder. It is an X-linked hereditary bleeding disorder caused by a deficient or defective coagulation factor VIII (Hemophilia A) or factor IX (Hemophilia B). Hemophilia A is more common than Hemophilia B. The X-linked inheritance pattern results in men expressing the disease and women typically being carriers. Under rare circumstances a woman can also show a bleeding phenotype.

A 13 year-old female presented with profuse vaginal bleeding. She had history of several hospital admissions because of bleeding manifestations like hematuria and epistaxis. Based on the pedigree analysis and results of factor IX assay tests she was diagnosed to have Hemophilia B of moderate severity. She was given hormonal and non-hormonal treatments as well as blood transfusions which stop the bleeding and corrected the anemia. A multidisciplinary approach of management involving the gynecologist, hematologist and a geneticist will be beneficial to the patient.

The inheritance, clinical manifestations, diagnosis and treatment of Hemophilia B in a female adolescent are discussed

Human ; Female ; Adolescent ; Hemophilia B ; X Chromosome Inactivation ; Uterine Hemorrhage

OBJECTIVETo explore the frequencies of heterozygosity in X-linked G6PD, P55, BTK, and FHL-1 gene exonic polymorphic loci among Chinese females and the value of determination of hematopoietic clonality by detection of these X-chromosome exonic polymorphisms based on X-chromosome inactivation patterns (XCIP)-transcription-based clonality assays (TCA).

METHODSGenomic DNA was extracted from peripheral blood of 446 Chinese healthy females. Allele-specific PCR (ASPCR) or PCR-restriction enzyme digestion method was applied for detecting G6PD, P55, BTK and FHL-1 polymorphisms. Those heterozygotic loci were used as markers to examine the hematopoietic clonality of bone marrow mononuclear cells by TCA from essential thrombocythemia (ET) patients with JAK2V617F mutation and myelodysplastic syndrome (MDS) patients with abnormal karyotype.

RESULTSAmong the total 446 genomic DNA samples, the frequencies of heterozygosity in G6PD, P55, BTK and FHL-1 loci were 12.8%, 29.4%, 52.0% and 46.4%, respectively. About 81.4% of females were heterozygous at one or more loci. All 10 ET patients with JAK2V617F mutation and 2 MDS patients with abnormal karyotype, which were heterozygotic in either locus, had monoclonal/oligoclonal hematopoiesis.

CONCLUSIONClonality detection based on X chromosome inactivation patterns-transcription based clonality assays is applicable to about 80% of Chinese females.

Adolescent ; Adult ; Aged ; Aged, 80 and over ; Alleles ; Asian Continental Ancestry Group ; genetics ; Chromosomes, Human, X ; Exons ; Female ; Genes, X-Linked ; Genetic Carrier Screening ; Genetic Linkage ; Glucosephosphate Dehydrogenase ; genetics ; Hematopoiesis ; genetics ; Humans ; Middle Aged ; Polymerase Chain Reaction ; methods ; Polymorphism, Single Nucleotide ; X Chromosome Inactivation ; Young Adult

OBJECTIVERett syndrome (RTT) is a neurodevelopmental disorder occurring almost exclusively in females as sporadic cases due to de novo mutations in the methyl-CpG-binding protein 2 gene (MECP2). Familial cases of RTT are rare and are due to X-chromosomal inheritance from a carrier mother. Recently, DNA mutations in the MECP2 have been detected in approximately 84.7% of patients with RTT in China. To explain the sex-limited expression of RTT, it has been suggested that de novo X-linked mutations occur exclusively in male germ cells resulting therefore only in affected daughters. To test this hypothesis, we have analyzed the parental origin of mutations and the XCI status in 15 sporadic cases with RTT due to MECP2 molecular defects.

METHODSAllele-specific PCR was performed to amplify a fragment including the position of the mutation. The allele-specific PCR products were sequenced to determine which haplotype contained the mutation. It was then possible to determine the parent of origin by genotyping the single nucleotide polymorphism (SNP) in the parents. The degree of XCI and its direction relative to the X chromosome parent of origin were measured in DNA prepared from peripheral blood leucocytes by analyzing CAG repeat polymorphism in the androgen receptor gene (AR).

RESULTSExcept for 2 cases who had a frameshift mutation; all the remaining 13 cases had a C-->T transition mutation. Paternal origin has been determined in all cases with the C-->T transition mutation. For the two frameshift mutations, paternal origin has been determined in one case and maternal origin in the other. The frequency of male germ-line transmission in mutations is 93.3%. Except for 2 cases who were homozygotic at the AR locus, of the remaining 13 cases, 8 cases had a random XCI pattern; the other five cases had a skewed XCI pattern and they favor expression of the maternal origin allele.

CONCLUSIONDe novo mutations in sporadic RTT occur almost exclusively on the paternally derived X chromosome and that this is most probably the cause for the high female: male ratio observed in sporadic cases with RTT. Random XCI was the main XCI pattern in sporadic RTT patients. The priority inactive X chromosome was mainly of paternal origin.

Chromosome Aberrations ; Chromosomes, Human, X ; Female ; Humans ; Male ; Methyl-CpG-Binding Protein 2 ; genetics ; Mutation ; Polymorphism, Single Nucleotide ; Rett Syndrome ; genetics ; X Chromosome Inactivation

X chromosome inactivation. In general, cancer cells are characterized by global genomic hypomethylation and focal hypermethylation of CpG islands, which are generally unmethylated in normal cells. Gene silencing by CpG hypermethylation at the promotors of tumor suppressor genes is probably the most common mechanism of tumor suppressor inactivation in cancer.]]>
Base Sequence ; Biological Processes ; CpG Islands ; Cytosine ; DNA ; DNA Methylation ; Epigenomics ; Gene Expression ; Gene Silencing ; Genes, Tumor Suppressor ; Genomic Imprinting ; Introns ; Memory ; Methylation ; Promoter Regions, Genetic ; X Chromosome Inactivation

Carcinoma, Small Cell ; genetics ; pathology ; Carcinoma, Transitional Cell ; genetics ; pathology ; Clone Cells ; DNA, Neoplasm ; genetics ; Humans ; Loss of Heterozygosity ; Lymphatic Metastasis ; Microsatellite Repeats ; Urinary Bladder Neoplasms ; genetics ; pathology ; X Chromosome Inactivation