title: CpG islands in human X-inactivation.
abstract: Sequence comparison analyses have been carried out for 19 genes escaping X-inactivation versus 73 genes subject to X-inactivation, and 100 randomly chosen X chromosome genes versus 100 randomly chosen autosomal genes. The coding sequence of the genes and their upstream and downstream flanking sequences were investigated using a series of windows (1 kb, 2 kb, 5 kb, 10 kb and 100 kb). No significant difference in number of LINE-L1 elements was observed in genes escaping X-inactivation compared to genes subject to X-inactivation. This result, therefore, does not support the suggestion that lack of LINE repeat elements is a key factor for genes escaping X-inactivation. However, significantly reduced numbers of CpG islands and SINE MIR elements were found to be associated with genes escaping X-inactivation. Compared to genes known to be inactivated, genes escaping X-inactivation were observed to have fewer CpG islands, particularly within the 2 kb upstream flanking sequence close to the coding region. The results suggest that CpG islands may play a role in the process of X-inactivation by providing sufficient DNA methylation targets for the maintenance of X-inactivation. Lack of CpG islands may be a major reason for genes escaping X-inactivation regulation.
authors.affiliation: Human Genetics, Duthie Building (808), University of Southampton, Tremona Road, Southampton SO16 6YD, UK. xiayi@well.ox.ac.uk
authors.forename: X
authors.initials: X
authors.lastname: Ke
authors.forename: A
authors.initials: A
authors.lastname: Collins
mesh_terms: D018899:CpG Islands / Q000235:genetics*; D004303:Dosage Compensation, Genetic; D006801:Humans; D017422:Sequence Analysis, DNA