title: Characterization of a supernumerary ring chromosome 1 mosaicism in two cell systems by molecular cytogenetic techniques and review of the literature.
abstract: We report on a 4-year-old boy with developmental delay and microcephaly with an additional small marker chromosome derived from chromosome 1 and detected in 14% of T-lymphocytes by conventional cytogenetics and in 9% of buccal smear cells by interphase FISH. Using molecular cytogenetic techniques, the marker chromosome was characterized as an extra ring chromosome consisting of euchromatic material from the proximal short arm of chromosome 1. We compare the cytogenetic data and the phenotype of our patient to those previously described cases with marker chromosome 1 mosaicism. We conclude that in addition to the straightforward molecular cytogenetic characterization of the euchromatic content of the ring chromosome, the investigation of a second cell system gives additional information about the tissue specific distribution of the supernumerary marker chromosome (SMC) and provides more reliable data for further karyotype/phenotype correlations and the prediction of the phenotypic outcome in prenatal cases.
authors.affiliation: Institute of Human Genetics, Charité, Campus Virchow-Klinikum, Humboldt-University, Berlin, Germany. Holger.Toennies@charite.de
authors.forename: Holger
authors.initials: H
authors.lastname: Tönnies
authors.forename: Luitgard M
authors.initials: LM
authors.lastname: Neumann
authors.forename: Berthild
authors.initials: B
authors.lastname: Grüneberg
authors.forename: Heidemarie
authors.initials: H
authors.lastname: Neitzel
mesh_terms: D002675:Child, Preschool; D025063:Chromosome Disorders / Q000235:genetics; D002878:Chromosomes, Human, Pair 1; D020732:Cytogenetic Analysis / Q000379:methods*; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007621:Karyotyping; D008297:Male; D008831:Microcephaly / Q000235:genetics; D009030:Mosaicism; D012196:Review Literature as Topic; D012303:Ring Chromosomes
chemical_list: D005819:Genetic Markers