title: Identification of supernumerary der(20) chromosomes by FISH in three patients.
abstract: Small supernumerary marker chromosomes of 3 patients were characterized at the molecular cytogenetic level. Two ring chromosomes and one metacentric marker were shown to be distamycinA/DAPI-negative and did not possess satellite regions after conventional banding techniques. Fluorescence in situ hybridization (FISH) was performed and in all 3 cases the supernumerary markers were shown to be derived from chromosome 20. Phenotypes are described and discussed with respect to karyotypes. Two of the patients are developmentally and/or phenotypically normal. The first patient has a ring chromosome, containing a small amount of euchromatic material; the second patient is the carrier of a small, metacentric and most probably heterochromatic marker. Patient 3 has physical anomalies, including a congenital heart defect and delayed motor development, but is intellectually almost normal. His marker chromosome is a ring containing a small amount of euchromatic material.
authors.affiliation: Cytogenetic Unit, Institute of Human Genetics, University of Bonn, Germany.
authors.forename: R
authors.initials: R
authors.lastname: Viersbach
authors.forename: H
authors.initials: H
authors.lastname: Engels
authors.forename: G
authors.initials: G
authors.lastname: Schwanitz
mesh_terms: D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations; D025063:Chromosome Disorders; D002890:Chromosomes, Human, Pair 20; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D008297:Male