title: A practical metaphase marker of the inactive X chromosome.
abstract: It is paradoxical that the inactivated X is the only chromosome that can be identified in the interphase nucleus, yet in metaphase, it is indistinguishable from its genetically active homolog unless special culture and staining procedures are employed. A specific inactivation-associated fold in proximal Xq resolves that paradox. We describe here how the fold in the proximal long arm can be used as a simple and reliable marker to identify the inactivated X in G-, Q-, or R-banded preparations. Several examples are given, including localization of the inactivation center to band Xq13 or q21.1, identification of nonrandom inactivation in X-chromosome rearrangements, identification of multiple active X chromosomes in tumor cell lines, analysis of X-inactivation patterns in female carriers of the fragile site at Xq27, and comparison of X-inactivation patterns among primate species.
authors.forename: D L
authors.initials: DL
authors.lastname: Van Dyke
authors.forename: W L
authors.initials: WL
authors.lastname: Flejter
authors.forename: M J
authors.initials: MJ
authors.lastname: Worsham
authors.forename: J R
authors.initials: JR
authors.lastname: Roberson
authors.forename: J V
authors.initials: JV
authors.lastname: Higgins
authors.forename: H M
authors.initials: HM
authors.lastname: Herr
authors.forename: S
authors.initials: S
authors.lastname: Knuutila
authors.forename: N
authors.initials: N
authors.lastname: Wang
authors.forename: V R
authors.initials: VR
authors.lastname: Babu
authors.forename: L
authors.initials: L
authors.lastname: Weiss
mesh_terms: D002871:Chromosome Banding; D004303:Dosage Compensation, Genetic; D005260:Female; D005819:Genetic Markers; D006801:Humans; D007621:Karyotyping; D008677:Metaphase; D014960:X Chromosome
chemical_list: D005819:Genetic Markers