title: Turner phenotype in a girl with a 45,X/46,XX/47,XX,+18 mosaicism.
abstract: We report a girl with Turner syndrome phenotype, whose karyotype on amniocyte culture was 45,X, while cytogenetic analysis on peripheral blood lymphocytes showed the presence of a mosaic chromosome constitution with three different cell lines: 45,X[5]/46,XX[3]/47,XX,+18 [35]. No signs of trisomy 18 were observed and a follow up during childhood revealed normal psychomotor development. Parental origin and mechanism of formation were studied using high polymorphic microsatellites and Quantitative Fluorescent PCR. The 18-trisomic cells showed one paternal allele and two maternal homozygous alleles at different loci of chromosome 18, suggesting a maternal M-II meiotic or a postzygotic error. A biparental origin of the X-alleles in the trisomic cells were determined, being the paternal allele retained in the 45,X cells. The possible mechanism of formation implying meiotic and/or mitotic errors is discussed.
authors.affiliation: Department of Genetics, Fundación Jimenez-Diaz, Madrid, Spain. ilorda@fjd.es
authors.forename: Isabel
authors.initials: I
authors.lastname: Lorda-Sanchez
authors.forename: Maria Jose
authors.initials: MJ
authors.lastname: Trujillo
authors.forename: Pilar
authors.initials: P
authors.lastname: Gomez-Garre
authors.forename: Marta Rodríguez
authors.initials: MR
authors.lastname: de Alba
authors.forename: Cristina
authors.initials: C
authors.lastname: Gonzalez-Gonzalez
authors.forename: Maria
authors.initials: M
authors.lastname: García-Hoyos
authors.forename: Carmen
authors.initials: C
authors.lastname: Ayuso
authors.forename: Carmen
authors.initials: C
authors.lastname: Ramos
mesh_terms: D002869:Chromosome Aberrations; D002887:Chromosomes, Human, Pair 18 / Q000235:genetics; D041321:Chromosomes, Human, X / Q000235:genetics; D005260:Female; D006801:Humans; D007621:Karyotyping; D008540:Meiosis / Q000235:genetics; D009030:Mosaicism / Q000235:genetics*; D010641:Phenotype; D011003:Ploidies; D014424:Turner Syndrome / Q000235:genetics*