title: Increased skewing of X chromosome inactivation with age in both blood and buccal cells.
abstract: The X chromosome inactivation pattern in peripheral blood cells becomes more skewed after age 55, and a genetic effect on this age-related skewing has been reported. We investigated the effect of age on X inactivation phenotype in blood, buccal cells and tissue from duodenal biopsies in 80 females aged 19-90 years. The X inactivation pattern correlated positively with age in blood (r = 0.238, P = 0.034) and buccal cells (r = 0.260, P = 0.02). The mean degree of skewing was higher in the elderly (>/=55 years) than in the young (<55 years) in blood (70.1 and 63.5%, respectively, P = 0.013) and in buccal cells (64.7 and 59.0%, respectively, P = 0.004). Correlation of X inactivation between the different tissues was high in all tissues with a tendency to increase with age for blood and buccal cells (P = 0.082). None of the duodenal biopsies had a skewed X inactivation, and the mean degree of skewing was similar in the two age groups. The tendency for the same X chromosome to be the preferentially active X in both blood and buccal cells with advancing age is in agreement with a genetic effect on age-related skewing and indicates that genes other than those involved in hematopoiesis should be investigated in the search for genes contributing to age related skewing.
authors.affiliation: Department of Medical Genetics, Faculty Division, Rikshospitalet, University of Oslo, Oslo, Norway. gun.peggy.knudsen@rikshospitalet.no
authors.forename: G P S
authors.initials: GP
authors.lastname: Knudsen
authors.forename: J
authors.initials: J
authors.lastname: Pedersen
authors.forename: O
authors.initials: O
authors.lastname: Klingenberg
authors.forename: I
authors.initials: I
authors.lastname: Lygren
authors.forename: K H
authors.initials: KH
authors.lastname: Ørstavik
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging; D001773:Blood Cells / Q000166:cytology*; D002610:Cheek; D041321:Chromosomes, Human, X; D004247:DNA / Q000378:metabolism; D004386:Duodenum / Q000378:metabolism; D005260:Female; D006801:Humans; D008875:Middle Aged; D010641:Phenotype; D049951:X Chromosome Inactivation
chemical_list: D004247:DNA