title: X-inactivation patterns in human embryonic and extra-embryonic tissues.
abstract: Mice have skewed X chromosome inactivation (XCI) in extraembryonic tissue while examination of human placentae have yielded conflicting results. We investigated XCI patterns in human embryonic and extra-embryonic tissues. First and early second trimester placental and foetal tissues were collected. Cytotrophoblasts were isolated from the placentae. Female samples were identified and X-inactivation patterns were determined by analysis of androgen receptor (HAR) methylation patterns. Among 55 females heterozygous at the HAR, 37 had random and 18 skewed XCI. In foetal tissues a skewed XCI pattern was only observed in one liver and one intestine sample. A greater incidence of skewed XCI pattern was present in extra-embryonic compared to embryonic tissues (P=0.022). A markedly skewed XCI pattern was only found in one cytotrophoblast sample. Random and skewed XCI patterns were detected in human embryonic and extra-embryonic tissues. The extra-embryonic tissue had a higher proportion of skewed XCI, but marked skewed XCI was uncommon in both tissues. Skewed XCI may not play a role in normal human placentation.
authors.affiliation: Department of Obstetrics and Gynecology, University of Iowa College of Medicine, Iowa City 52242, USA.
authors.forename: S-M
authors.initials: SM
authors.lastname: Zeng
authors.forename: J
authors.initials: J
authors.lastname: Yankowitz
mesh_terms: D000328:Adult; D002469:Cell Separation; D004247:DNA / Q000032:analysis; D019175:DNA Methylation; D004303:Dosage Compensation, Genetic; D004622:Embryo, Mammalian / Q000166:cytology / Q000378:metabolism; D005314:Embryonic and Fetal Development / Q000235:genetics*; D005260:Female; D006579:Heterozygote; D006801:Humans; D008297:Male; D016133:Polymerase Chain Reaction; D011247:Pregnancy; D011261:Pregnancy Trimester, First; D011262:Pregnancy Trimester, Second; D011944:Receptors, Androgen / Q000235:genetics / Q000378:metabolism; D012732:Sex Determination Analysis; D014327:Trophoblasts / Q000166:cytology / Q000378:metabolism
chemical_list: D011944:Receptors, Androgen; D004247:DNA