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Search Results: 1 - 10 of 11737 matches for " x chromosome "
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No correlation between X chromosome inactivation pattern and autistic spectrum disorders in an Italian cohort of patients  [PDF]
Natalia Cannelli, Elisabetta Tabolacci, Claudia Rendeli, Giovanni Neri, Fiorella Gurrieri
Open Journal of Genetics (OJGen) , 2011, DOI: 10.4236/ojgen.2011.13007
Abstract: Autistic spectrum disorders (ASD) occur more frequently in males, suggesting a major pathogenic role for genes located on the X-chromosome. The analysis of X chromosome inactivation (XCI) pattern may help to identify XCI skewing in those families in which such genes are involved, even without identifying the specific genetic mutation. In order to identify such families, we determined the XCI pattern in 40 females with ASD and 58 mothers of children with ASD, as well as in 80 matched control females. The X inactivation assay was carried out on genomic DNA extracted from peripheral blood. XCI was calculated for informative heterozygous individuals as the ratio of the peak area of two alleles of the highly polymorphic CAG repeat of the androgen receptor (AR) gene (Xq11-12). Our results indicate that there is no difference in XCI pattern both in ASD females and in the mothers of ASD patients when compared with the appropriate controls. These findings suggest that the contribution of X-linked genes to the etiology of ASD is still likely but it is not supported by X-inactivation patterns on peripheral blood cells.
A case of acute lymphoblastic leukemia with additional chromosomes X and 5 associated with a Philadelphia chromosome in the bone marrow
Burak Durmaz,Asude Alpman Durmaz,Emin Karaca,Güray Saydam
Turkish Journal of Hematology , 2010,
Abstract: We report herein a very rare case of acute lymphoblastic leukemia having a chromosomal constitution of 48,XY,+X,+5,t(9;22)(q34;q11) in the bone marrow. A patient with additional chromosomes X and 5 with a Philadelphia chromosome has not been reported previously. However, no abnormal karyotype was obtained from the lymphocytes in our patient, and he did not have the characteristics of Klinefelter syndrome. He achieved a complete remission with IDA-FLAG and dasatinib therapy. The mechanism of trisomy 5 or any other chromosomal aneuploidy in the pathogenesis of leukemogenesis remains unclear. Further studies involving the genes affected by this karyotype and their products may lead to strategies to further increase the understanding of drug-resistant acute lymphoblastic leukemia and may represent the next frontier in the targeted therapy of those patients.
SRY in an XX male does not influence random chromosome X inactivation: Cytogenetic evidence. Definition of the boundaries of the translocated Y segment through FISH and PCR-RT in a case report and review of the literature  [PDF]
Mariano Stabile, Vincenzo Altieri, Rosa Salzillo, Panfilo Marrollo, Guglielmo Stabile, Tina Iuorio, Bianca Moscato
Open Journal of Genetics (OJGen) , 2013, DOI: 10.4236/ojgen.2013.32A3004
Abstract: We report a case of an SRY positive XX male. The phenotype was completely masculinised except for the reduced facial hair; testes were small, and azoospermia was present. The patient’s metaphases, coloured with acridine-orange to reveal the late replicating X chromosome, were sequentially hybridised with SRY and X centromeric probes: a random X chromosome inactivation pattern (XCIP) was present, with SRY present about half the time on both the active X and the inactive X. The most likely hypothesis is that the translocated SRY gene escaped inactivation as part of the entire X Pseudo Autosomal telomeric Region 1 (PAR 1). This hypothesis can explain the masculine phenotype, which would be incompatible with a halved expression of SRY. Review of the literature about the association of 46, XX males with a specific XCI pattern is made. The analysis of region AZF and QF-PCR for Y polymorphic loci allowed us to define the boundaries of the translocated Y segment as restricted to the region around the SRY locus. Chromosomal fragility analysis, using SCE (Sister Chromatid Exchanges), ruled out chromosomal fragility as a predisposing factor in the proband’s father; in addition, no chromosome Y polymorphic variant (inversion, Y qh +/﹣), was present in the proband’s father. However, like the AZF region c microdeletions and PRKX/PRKY translocation XX males, a particular Y haplotype could be also in this case a predisposing factor.
Double Partial Monosomies (10p- and Xp-) in a Female Baby with Choanal Atresia
Jia-Woei Hou
Chang Gung Medical Journal , 2002,
Abstract: Chromosomal abnormalities involving double partial monosomies are very rare. Afemale infant with non-mosaic monosomy 10p13
The mus309 mutation, defective in DNA double-strand break repair, increases the frequency of X-ray-induced somatic crossing over in Drosophila melanogaster, but the effect is not dose-rate dependent  [PDF]
Petter Portin
Open Journal of Genetics (OJGen) , 2012, DOI: 10.4236/ojgen.2012.21004
Abstract: Effect of a 1000 R dose of hard X-rays, with two different dose-rates viz. 300 and 1000 R/min on somatic crossing over in the X chromosome of Drosophila melanogaster was studied in two different genotypes. Irradiation was given during the first-instar larval stage of the development. In the control crosses the flies carried wild-type autosomes, but in the experimental crosses the 3rd chromosomes carried a DNA double-strand break repair deficient mus309 mutant gene constitution. As expected, the frequency of X-ray-induced somatic crossing over increased in the mutant flies with both dose-rates of irradiation. As also expected, in the control flies irradiation given with the 300 R/min dose-rate caused more somatic crossovers than irradiation given with the 1000 R/ min rate. However, rather unexpectedly, in the experimental flies there was no significant difference in the frequency of somatic crossing over between the two dose-rates of irradiation. The results can be explained by assuming that X-ray-induced somatic crossing over is a two-step event, and that the mechanism which repairs the lesion caused by the irradiation is controlled by the mus309 gene. In the control flies the repairing mechanism is capable to recover if the irradiation is given with a short term high dose-rate, but is not capable to recover if the irradiation is given with a long lasting low dose-rate. However, in the experimental mutant flies the repairing mechanism is only poorly recovered irrespective of the dose-rate.
Analysis of Linkage for Ten X-STR Markers in a Rio de Janeiro (Brazil) Three-Generation Family Sample  [PDF]
Roberto Chan, Elizeu Fagundes de Carvalho, Juliana Gozi de Aquino, Dayse Aparecida da Silva, Gisele L?bo-Hajdu
Open Journal of Genetics (OJGen) , 2014, DOI: 10.4236/ojgen.2014.43025

Recently, typing of polymorphisms on the X chromosome has become a standard technique in forensic genetics and a growing number of short tandem repeats (STR) has been established in this chromosome related to genetic population studies. Knowledge of marker recombination is very important especially when the X chromosome typing is used in forensic kinship analysis. It is known that the meiotic recombination is not a simple function of the physical distance between segments of the DNA but the recombination events between them tend to be clustered at special regions of the chromosome. Information on the rate of recombination among markers can be gathered by studying families through several generations. In this work we have typed DNA samples of pedigree consisting of nineteen families in Rio de Janeiro, constituted of grandfather, mother and grandson, and in some cases grandmother and aunt, and reported the recombination of 10 STR markers of the X chromosome. The study of the linkage analysis using the LOD score has shown that the marker pairs DXS8378-DXS7423, DXS7132-DXS9898, DXS7132-GATA172D05 DXS9898-DXS7133 and DXS6809-DXS7133 are not transmitted in a random way, during a recombination event.

Incontinência pigmentar ligada ao X ou síndrome de Bloch-Sulzberger: relato de um caso
Pereira, Marcela A. C.;Mesquita, Lismary A. de F.;Budel, Anelise R.;Cabral, Carolina S. P.;Feltrim, Amanda de S.;
Anais Brasileiros de Dermatologia , 2010, DOI: 10.1590/S0365-05962010000300013
Abstract: incontinentia pigmenti is a rare x-linked genodermatosis that affects mainly female neonates. skin manifestations are the most common and occur in four quite distinct phases. a female infant presented vesiculobullous lesions on trunk and limbs, and a verrucous lesion on the right palm. biopsy revealed eosinophil exocytosis and pigment incontinence, confirming the clinical hypothesis. although uncommon, incontinentia pigmenti should be taken into consideration as a possible differential diagnosis when vesiculobullous and verrucous lesions are present in childhood.
Retinosis pigmentaria con herencia recesiva ligada al cromosoma x. Caracterización oftalmológica
Ramírez Castro,Tomás; Lorenzo González,María E.; Hernández Baguer,Raisa;
Revista Cubana de Oftalmolog?-a , 2003,
Abstract: a prospective study was conducted aimed at describing the behavior of x linked retinitis pigmentosa in the provinces of havana city and havana. the most common age groups were 30-44, in havana city, and 15-29, in havana. there were 31 cases in the first province with a prevalence rate of 0.014 per 10 000 inhabitants. guanabacoa was the municipality with the highest rate. 17 cases were observed in havana with a provincial prevalence of 0.24 per 10 000 inhabitants. güines municipality had the highest prevalence. the stage-onset relation showed 16 patients in the early onset with 81.2 % in stage iii, in havana city. in havana, there were 12 with this onset with 33.3 % in stage iii and the same figure in stage iv.
Fine-scale evolutionary genetic insights into Anopheles gambiae X-chromosome  [PDF]
Hemlata Srivastava, Jyotsana Dixit, Aditya P. Dash, Aparup Das
Journal of Biomedical Science and Engineering (JBiSE) , 2009, DOI: 10.4236/jbise.2009.25045
Abstract: Understanding the genetic architecture of indi-vidual taxa of medical importance is the first step for designing disease preventive strategies. To understand the genetic details and evolu-tionary perspective of the model malaria vector, Anopheles gambiae and to use the information in other species of local importance, we scanned the published X-chromosome se-quence for detail characterization and obtain evolutionary status of different genes. The te-locentric X-chromosome contains 106 genes of known functions and 982 novel genes. Majori-ties of both the known and novel genes are with introns. The known genes are strictly biased towards less number of introns; about half of the total known genes have only one or two in-trons. The extreme sized (either long or short) genes were found to be most prevalent (58% short and 23% large). Statistically significant positive correlations between gene length and intron length as well as with intron number and intron length were obtained signifying the role of introns in contributing to the overall size of the known genes of X-chromosome in An. gam-biae. We compared each individual gene of An. gambiae with 33 other taxa having whole ge-nome sequence information. In general, the mosquito Aedes aegypti was found to be ge-netically closest and the yeast Saccharomyces cerevisiae as most distant taxa to An. gambiae. Further, only about a quarter of the known genes of X-chromosome were unique to An. gambiae and majorities have orthologs in dif-ferent taxa. A phylogenetic tree was constructed based on a single gene found to be highly orthologous across all the 34 taxa. Evolutionary relationships among 13 different taxa were in-ferred which corroborate the previous and pre-sent findings on genetic relationships across various taxa.
The role of X-chromosome inactivation in female predisposition to autoimmunity
Smita Chitnis, Joanita Monteiro, David Glass, Brian Apatoff, Jane Salmon, Patrick Concannon, Peter K Gregersen
Arthritis Research & Therapy , 2000, DOI: 10.1186/ar118
Abstract: A reduction in the sex ratio (male : female) is characteristic of most autoimmune disorders. The increased prevalence in females ranges from a modest 2:1 for multiple sclerosis [1], to approximately 10:1 for systemic lupus erythematosus [2]. This tendency toward autoimmunity in females is often ascribed to hormonal differences, because in a number of experimental disease models estrogens exacerbated disease, and androgens can inhibit disease activity [3,4]. However, human studies have failed to demonstrate a clear-cut influence of hormonal environment on disease susceptibility to lupus or other autoimmune disorders. In addition, many childhood forms of autoimmunity, such as juvenile rheumatoid arthritis, exhibit female predominance [5]. Interestingly, juvenile (type 1) diabetes is an exception to this general trend, with a sex ratio close to 1 in most studies [6]. Therefore, it is reasonable to consider alternative explanations for the increased prevalence of autoimmune diseases in human females.A unifying feature of autoimmune disorders appears to be the loss of immunologic tolerance to self-antigens, and in many of these diseases there is evidence that T-cell tolerance has been broken. The most profound form of T-cell tolerance involves deletion of potentially self-reactive T cells during thymic selection. Thus, lack of exposure to a self-antigen in the thymus may lead to the presence of autoreactive T cells and may increase the risk of autoimmunity. An elegant example of this has recently been reported [7].The existence of X-chromosome inactivation in females offers a potential mechanism whereby X-linked self-antigens may escape presentation in the thymus or in other peripheral sites that are involved in tolerance induction. Early in female development, one of the two X chromosomes in each cell undergoes an ordered process of inactivation, with subsequent silencing of most genes on the inactive X chromosome [8]. This phenomenon occurs at a very early embryonic st
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