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.

Specific cloning of DNA fragments absent from the DNA of a male patient with an X chromosome deletion

Abstract: A method that allows the specific cloning of DNA fragments absent from patients homozygous or hemizygous for chromosomal deletions is described. The method involves phenol-accelerated competitive DNA reassociation and subsequent molecular cloning of appropriately reassociated molecules. The deletion DNA sample utilized in the competition was isolated from a patient with a minute interstitial deletion in the short arm of the X chromosome. Sheared DNA isolated from a male child, who was diagnosed as having Duchenne muscular dystrophy, chronic granulomatous disease, and retinitis pigmentosa, was combined in a 200-fold excess with Mbo I-cleaved DNA isolated from a 49, XXXXY human lymphoid cell line, and the mixture was subjected to a phenol-enhanced reassociation technique. Analysis of 81 unique segments derived from cloned reassociated DNA molecules has led to the identification of 4 (5%) human DNA fragments that are absent from the male patient's DNA. The 4 clones were localized, on the basis of hybridization with restriction nuclease-digested genomic DNA from a panel of human and human-rodent hybrid cell lines, into three regions surrounding band 21 of the short arm of the normal human X chromosome. These clones are potential linkage markers for the diseases affecting this boy. Each clone, as well as others obtainable by this approach, may also serve as a starting point in the eventual cloning of these three X-linked-disease loci. Extension of this approach to other loci, including human tumors potentially homozygous for small deletions, should also be possible.

Clonal Analysis Using Recombinant DNA Probes from the X-Chromosome

Abstract: It has been demonstrated that restriction fragment length polymorphisms of X-chromosome genes can be used in conjunction with methylation patterns to determine the clonal composition of human tumors. In this report, we show that several X-chromosome probes can be used for such analyses. In particular, probes derived from the hypoxanthine phosphoribosyltransferase gene and the phosphoglycerate kinase gene could be used for clonal analysis in over 50% of American females. The X-inactivation patterns observed with these probes were found to accurately reflect clonality in more than 95% of 92 tumors tested.

Multiple marker mapping of quantitative trait loci in a cross between outbred wild boar and large white pigs

Abstract: A quantitative trait locus (QTL) analysis of growth and fatness data from a three generation pig experiment is presented. The population of 199 F2 animals was derived from a cross between wild boar and Large White pigs. Animals were typed for 240 markers spanning 23 Morgans of 18 autosomes and the X chromosome. A series of analyses are presented within a least squares framework. First, these identify chromosomes containing loci controlling trait variation and subsequently attempt to map QTLs to locations within chromosomes. This population gives evidence for a large QTL affecting back fat and another for abdominal fat segregating on chromosome 4. The best locations for these QTLs are within 4 cM of each other and, hence, this is likely to be a single QTL affecting both traits. The allele inherited from the wild boar causes an increase in fat deposition. A QTL for intestinal length was also located in the same region on chromosome 4 and could be the same QTL with pleiotropic effects. Significant effects, owing to multiple QTLs, for intestinal length were identified on chromosomes 3 and 5. A single QTL affecting growth rate to 30 kg was located on chromosome 13 such that the Large White allele increased early growth rate, another QTL on chromosome 10 affected growth rate from 30 to 70 kg and another on chromosome 4 affected growth rate to 70 kg.

Isolation of an active human transposable element

Abstract: Two de novo insertions of truncated L1 elements into the factor VIII gene on the X chromosome have been identified that produced hemophilia A. A full-length L1 element that is the likely progenitor of one of these insertions was isolated by its sequence identity to the factor VIII insertion. This L1 element contains two open-reading frames and is one of at least four alleles of a locus on chromosome 22 that has been occupied by an L1 element for at least 6 million years.

Minor Xp21 chromosome deletion in a male associated with expression of duchenne muscular dystrophy, chronic granulomatous disease, retinitis pigmentosa, and McLeod syndrome

Abstract: We are reporting a male patient who suffered from chronic granulomatous disease associated with cytochrome b−245 deficiency and McLeod red cell phenotype, Duchenne muscular dystrophy, and retinitis pigmentosa. On cytogenetic analysis, he seemed to have a very subtle interstitial deletion of part of band Xp21. Since it was impossible to know whether this material was truly deleted or inserted elsewhere in the genome, somatic cell and molecular studies were carried out. In somatic cell hybrids, the deleted X chromosome was isolated on a Chinese hamster background. Southern blot analysis with 20 single-copy probes, that had been mapped to the X short arm, led to the discovery of one (probe 754) that is missing from this patient's X chromosome and also from his total DNA. This proves that he, indeed, has a deletion rather than a balanced insertion. The results provide cytological mapping information for the X-linked phenotypes present in this patient. Furthermore, probe 754 recognizes a restriction fragment length polymorphism of high frequency that makes it the most powerful probe currently available for linkage studies with X-linked muscular dystrophy.