title: Delineation of supernumerary marker chromosomes in 38 patients.
abstract: We present cytogenetic and clinical data on 38 patients with supernumerary marker chromosomes (SMCs). SMCs were characterized using a strategy combining classical banding techniques and molecular cytogenetic studies. Cases were ascertained prenatally, postnatally, and after fetal death. In 26 patients (68%), the SMC originated entirely from acrocentric chromosomes. Among these, most patients carried a der(15). In 11 patients (29%), they were of nonacrocentric origin, including 9 autosomal and 2 gonosomal marker chromosomes. In 1 patient the SMC was of partially acrocentric origin. Patients with small derivatives of chromosome 15 [der(15)] had a normal phenotype. Those with a larger der(15) showed phenotypical abnormalities. Patients with supernumerary marker chromosomes derived from chromosomes 13 or 21, and 14 appeared to have a low risk of abnormalities. Out of this group only 1 patient who carried an additional r(21) had physical anomalies. Patients with an SMC originating from chromosome 22 showed physical abnormalities in 2 out of 6 cases. Supernumerary marker chromosomes identified as i(9p), i(12p), and der(18) were all associated with an abnormal phenotype. Two of the derivatives of chromosome 20 analyzed were correlated with a normal phenotype, while the carrier of the third one showed physical anomalies and motor retardation. Of 2 patients with an extra der(X), 1 was normal and 1 showed an abnormal phenotype.
authors.affiliation: 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: U
authors.initials: U
authors.lastname: Gamerdinger
authors.forename: M
authors.initials: M
authors.lastname: Hansmann
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D002869:Chromosome Aberrations / Q000235:genetics*; D025063:Chromosome Disorders; D002874:Chromosome Mapping; D002882:Chromosomes, Human, Pair 13; D002883:Chromosomes, Human, Pair 14; D002890:Chromosomes, Human, Pair 20; D002891:Chromosomes, Human, Pair 21; D002892:Chromosomes, Human, Pair 22; D005260:Female; D005819:Genetic Markers; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D007223:Infant; D007231:Infant, Newborn; D007621:Karyotyping; D008297:Male; D008677:Metaphase; D010641:Phenotype; D016133:Polymerase Chain Reaction
chemical_list: D005819:Genetic Markers