Disease relevance of Chromosomes, Human, X

• Dysmyelination of PLP transgenic mice provides experimental evidence that Pelizaeus-Merzbacher disease, previously associated with a partial duplication of the human X chromosome, can be caused by doubling of the PLP gene dosage [1].
• Analysis of linkage intervals from 125 unrelated families with nonsyndromic X-linked mental retardation (NS-XLMR) has revealed that the respective gene defects are conspicuously clustered in defined regions of the human X-chromosome, with approximately 30% of all mutations being located on the proximal Xp [2].
• The folate-sensitive fragile site FRAXE is located in proximal Xq28 of the human X chromosome and lies approximately 600 kb distal to the fragile X syndrome (FRAXA) fragile site at Xq27 [3].
• Regional assignment of the steroid sulfatase-X-linked ichthyosis locus: implications for a noninactivated region on the short arm of human X chromosome [4].
• A subclone of these simian virus 40 (SV40)-transformed cells (6TGR-SV-tfm) selected in 6-thioguanine and lacking hypoxanthine phosphoribosyltransferase was used to produce a series of mouse--human hybrids containing the normal human X chromosome or various X autosome-translocation chromosomes (expressing only segments of the human X chromosome) [5].

High impact information on Chromosomes, Human, X

• Differentially methylated forms of histone H3 show unique association patterns with inactive human X chromosomes [6].
• The candidate spermatogenesis gene RBMY has a homologue on the human X chromosome [7].
• Analysis of 84 human X chromosomes for the presence of interrupting AGG trinucleotides within the CGG repeat tract of the FMR1 gene revealed that most alleles possess two interspersed AGGs and that the longest tract of uninterrupted CGG repeats is usually found at the 3' end [8].
• We have cloned the fragile site FRAXE and demonstrate that individuals with this fragile site possess amplifications of a GCC repeat adjacent to a CpG island in Xq28 of the human X chromosome [9].
• Transcription analysis of human-rodent hybrid cell lines containing "inactive" human X chromosomes suggests that ZFX escapes X inactivation [10].

Biological context of Chromosomes, Human, X

• Human AR genomic DNA was cloned from a flow-sorted human X chromosome library by using a consensus nucleotide sequence from the DNA-binding domain of the family of nuclear receptors [11].
• A panel of over 50 hybrid cells containing varying portions of the long arm of the human X chromosome have been obtained by chromosome-mediated gene transfer (CMGT) of human chromosomes to mouse cells deficient in HPRT [12].
• A glyceraldehyde-3-phosphate dehydrogenase pseudogene on the short arm of the human X chromosomes defines a multigene family [13].
• Expression of the G6PD locus on the human X chromosome is associated with demethylation of three CpG islands within 100 kb of DNA [14].
• The temperature-sensitive ts A1S9 mutation of mouse L cells was previously shown to affect nuclear DNA replication and to be complemented by active and inactive human X chromosomes in human-ts A1S9 somatic cell hybrids [15].

Anatomical context of Chromosomes, Human, X

• The 5' region of the gene encoding human X chromosome-linked phosphoglycerate kinase 1 (PGK1) is a promoter-containing CpG island known to be methylated at 119 of 121 CpG dinucleotides in a 450-base-pair region on the inactive human X chromosome in the hamster-human cell line X8-6T2 [16].
• A series of hamster lung fibroblast and mouse lymphocyte cell lines carrying fragments of the wild type human X-chromosome was analyzed for vasopressin renal-type V2 receptor expression, to test the hypothesis that the NDI locus may have identity with the V2 receptor gene [17].
• Furthermore, 97.3% of endothelial cells derived from CD34+ cells contained human X chromosome only [18].
• To determine the effect of reversal of inactivation on the expression of XIST, we studied human X chromosomes that had been induced to reverse X inactivation by hybridization of chorionic villi cells from term placentas with mouse A9 cells [19].

Associations of Chromosomes, Human, X with chemical compounds

• Differential expression of steroid sulphatase locus on active and inactive human X chromosome [20].
• It has been shown that 5-azacytidine (5-Aza-Cyd) can reactivate genes on the inactive human X chromosome [21].
• Locus on human X chromosome for dihydrotestosterone receptor and androgen insensitivity [22].
• Among the genes recently identified at the tip of the long arm of the human X chromosome, a novel gene, C1, encodes a protein that appears to represent a newly discovered member of the group of signaling proteins involved in regulation of the small GTP binding proteins of the ras superfamily [23].
• Moreover, the human isozymes of hlucose-6-phosphate dehydrogenase (EC 1.1.1.49; D-glucose 6-phosphate:NADP 1-oxidoreductase) and phosphoglycerate kinase (EC 2.7.2.3;ATP:3-phospho-D-glycerate 1-phosphotransferase), whose genes have been linked with the HPRT gene to the long are of the human X chromosome, were also absent [24].

Gene context of Chromosomes, Human, X

• The studies show that 5-azacytidine can induce heritable changes in the inactive human X chromosome resulting in the expression of G6PD activity at a level lower than that from an active human X chromosome [25].
• We report the physical linkage of the gene encoding one of the subunits of the GABAA receptor (GABRA3) to the polymorphic locus DXS374 on the human X chromosome at Xq28 [26].
• Three fragile sites, FRAXA, FRAXE and FRAXF lie in the Xq27-28 region of the human X chromosome [27].
• Sequence analyses of bisufite-modified genomic DNA from somatic cell hybrids with either the active or the inactive human X chromosome reveal that TCEAL7 is subjected to X chromosome inactivation [28].
• Reactivation of an inactive human X chromosome introduced into mouse embryonal carcinoma cells by microcell fusion with persistent expression of XIST [29].

Analytical, diagnostic and therapeutic context of Chromosomes, Human, X

• RT-PCR analysis of somatic cell hybrids containing either an active or an inactive human X chromosome on a rodent background demonstrated that XE169 escapes X-inactivation [30].
• The L1 protein appears to be encoded by a single gene that has been located on the human X chromosome by in situ hybridization [31].
• This may reflect the existence of at least one inversion within this repetitive DNA array in the centromeric region of the human X chromosome [32].
• We investigated the pol fragment of HERV-W on the human X chromosome by the polymerase chain reaction (PCR) using a monochromosomal somatic cell hybrid DNA panel and compared these with related sequences in the genome database [33].

References