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X chromosome

About: X chromosome is a research topic. Over the lifetime, 9862 publications have been published within this topic receiving 407354 citations. The topic is also known as: GO:0000805 & chrX.


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Journal ArticleDOI
TL;DR: E(y)n (with n from 1–6) mutations enhanced the expression of several y mutations induced by different insertions into the yellow locus, which is a damage of bristle and hair pigmentation which is not suppressed by su(Hw) mutations.
Abstract: We used a system with a mobilized Stalker transposable element, sometimes in combination with P-M hybrid dysgenesis, in the search for new mutations interfering with the y 2 mutation induced by mdg4 (gypsy) insertion into the yellow locus. A novel gene, modifier of mdg4, was detected in chromosome 3. The mutation mod(mdg4) either enhanced or suppressed phenotypic changes in different mutations induced by mdg4 insertions. Thus, mod(mdg4) seems to be involved in the control of mdg4 expression. Six other loci designated as enhancers of yellow were also detected. The e(y) n (with n from 1–6) mutations enhanced the expression of several y mutations induced by different insertions into the yellow locus. The major change is a damage of bristle and hair pigmentation which is not suppressed by su(Hw) mutations. On the other hand, e(y) n alleles do not interact with mdg4 induced mutations in other loci. All e(y) n genes are located in different regions of the X chromosome. One may speculate that e(y) n genes are involved in trans-regulation of the yellow locus and possibly of some other loci.

107 citations

Journal ArticleDOI
TL;DR: The analysis places the gene defect for this disorder in the region of DXYS1 and p58—1, near the centromere of the X chromosome, and finds only loose linkage or nonlinkage to nine other markers located elsewhere on the chromosome.
Abstract: We used probes for DNA polymorphisms on the X chromosome to study genetic linkage in four families with X-linked neuropathy. Despite clinical variability, all four families showed the same linkage pattern. We found evidence in each family of linkage to the marker DXYS1 on the proximal long arm of the X chromosome, as reported by others. We also found linkage to p58-1 (DXS14) on the proximal short arm. We found only loose linkage or nonlinkage to nine other markers located elsewhere on the chromosome. Our analysis places the gene defect for this disorder in the region of DXYS1 and p58-1, near the centromere of the X chromosome.

107 citations

Journal ArticleDOI
TL;DR: This issue of PNAS, Carrel et al. (3) report such a systematic analysis of the inactivation status of many X-linked genes in the Human Genome Project, and the data are so extensive that they are summarized in the paper but are fully accessible only as a file on the World Wide Web.
Abstract: In many organisms, differentiation of the sex chromosome complement resulted in the coordinated regulation of genes on whole chromosomes to equalize gene expression between the sexes. In mammals, X inactivation evolved to restore equal expression of X-linked genes in males and females (1). Although X inactivation consists in the general repression of most genes on the X, some genes escape inactivation (reviewed in ref. 2). Recent advances in the Human Genome Project now allow the inactivation status of many X-linked genes to be systematically studied. In this issue of PNAS, Carrel et al. (3) report such a systematic analysis. Their data are so extensive that they are summarized in the paper but are fully accessible only as a file on the World Wide Web (www.pnas.org/supplementary.shtml).

107 citations

Journal ArticleDOI
TL;DR: The relationship between type of MeCP2 mutation, X-inactivation status, and clinical phenotype of Rett syndrome is complex and likely involves other environmental and polygenic modifiers.
Abstract: Rett syndrome is a neurodevelopmental disorder of early postnatal brain growth in girls. Patients show a normal neonatal period with subsequent developmental regression and a loss of acquired skills (communication and motor skills), deceleration of head growth, and development of typical hand stereotypies. Recent studies have shown that mutations in the X-linked methyl CpG binding protein 2 gene (MeCP2) cause most typical cases of Rett syndrome. The MeCP2 gene encodes a protein that binds methylated cytosine residues of CpG dinucleotides and mediates, with histone deacetylases and transcriptional repressors, the transcription "silencing" of other genes. Girls with Rett syndrome exhibit mosaic expression for the MeCP2 defect at the cellular level, with most patients showing random X-inactivation and approximately equal numbers of cells expressing the normal MeCP2 gene and the mutated MeCP2 gene. In rare cases, females with a MeCP2 mutation escape phenotypic expression of the disorder because of nonrandom X-inactivation and the preferential inactivation of the mutated MeCP2 allele. Nonrandom patterns of X-inactivation may also contribute to the clinical variability often seen in girls with Rett syndrome. The spectrum of clinical phenotype caused by MeCP2 mutations is wide, including milder "preserved speech" variants, the severe congenital Rett variant, and a subset of X-linked recessive mental retardation in boys. Studies have shown that atypical and classical Rett syndrome can caused by the same MeCP2 mutations, indicating clinical phenotype is variable even among girls with the same MeCP2 mutation. The relationship between type of MeCP2 mutation, X-inactivation status, and clinical phenotype of Rett syndrome is complex and likely involves other environmental and polygenic modifiers.

107 citations

Journal ArticleDOI
TL;DR: It is concluded that the sex of mouse preimplantation embryos can be accurately determined through detection of the Y-specific sequences using the two-step PCR method, even with the single blastomeres separated at the two -cell stage.
Abstract: Detection of genes known to be present on the mammalian Y chromosome was adapted for sexing mouse early embryos using the polymerase chain reaction (PCR) method. Sry and Zfy genes located in the sex-determining region of the Y chromosome were chosen for Y-specific target sequences, and DXNds3 sequence on the X chromosome was chosen for control. The two-step PCR method using two pairs of primers for each of the target sequences was employed for detecting the sequences. When DNAs of male and female mice were amplified with these primers, male-specific fragments were detected even in DNAs that were equivalent in amount to two cells. Mouse embryos at the two-cell stage were separated into two individual blastomeres, and one blastomere was karyotyped at the second cleavage. The remaining blastomere was subjected to PCR amplification immediately or after having been cultured for 48 h up to the morula stage. The Sry and Zfy sequences were detected in about half the embryos; detection of the Sry and Zfy sequences corresponded exactly to the presence of the Y chromosome, except in one sample of male morula in which embryos may have been lost before the PCR amplification. It is concluded that the sex of mouse preimplantation embryos can be accurately determined through detection of the Y-specific sequences using the two-step PCR method, even with the single blastomeres separated at the two-cell stage.

107 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202372
2022124
2021192
2020179
2019190
2018186