title: Centromeric association of small supernumerary marker chromosomes with their sister-chromosomes detected by three dimensional molecular cytogenetics.
abstract: BACKGROUND
  Small supernumerary marker chromosomes (sSMC) are detected in 0.043% of general population and can be characterized for their chromosomal origin, genetic content and shape by molecular cytogenetic approaches. Even though recently progress was achieved towards genotype-phenotype-correlations of sSMC, nothing is known on the influence that an additional derivative extra chromosome has on the nuclear architecture.
  
  
  RESULTS
  Here we present the first three-dimensional interphase fluorescence in situ hybridization (FISH) studies for the nuclear architecture of sSMC. It could be shown that sSMC derived from chromosomes 15, 16 or 18 preferentially colocalized with one of their corresponding sister chromosomes. This was true in B- and T-lymphocytes as well as in skin fibroblasts. Additionally, a case with a complex sSMC with a karyotype 47,XY,+der(18)t(8;18)(8p23.2 ~ 23.1;18q11.1) was studied. Here the sSMC co-localized with one homologous chromosome 8 instead of 18.
  
  
  CONCLUSIONS
  Overall, there is a kind of "attraction" between an sSMC and one of its homologous sister chromosomes. This seems to be transmitted by the euchromatic part of the sSMC rather than its heterochromatic one.
authors.affiliation: Jena University Hospital, Friedrich Schiller University, Institute of Human Genetics, Kollegiengasse 10, D-07743 Jena, Germany. i8lith@mti.uni-jena.de.
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Klein
authors.forename: Marina
authors.initials: M
authors.lastname: Manvelyan
authors.forename: Isabella
authors.initials: I
authors.lastname: Simonyan
authors.forename: Ahmed B
authors.initials: AB
authors.lastname: Hamid
authors.forename: Roberta Santos
authors.initials: RS
authors.lastname: Guilherme
authors.forename: Thomas
authors.initials: T
authors.lastname: Liehr
authors.forename: Tatyana
authors.initials: T
authors.lastname: Karamysheva