title: Identification of small marker chromosomes using microarray comparative genomic hybridization and multicolor fluorescent in situ hybridization.
abstract: BACKGROUND
  Marker chromosomes are small supernumerary chromosomes that cannot be unambiguously identified by chromosome banding techniques alone. However, the precise characterization of marker chromosomes is important for prenatal diagnosis and proper genetic counseling. In this study, we evaluated the chromosomal origin of marker chromosomes using a combination of banding cytogenetics and molecular cytogenetic techniques including diverse fluorescence in situ hybridization (FISH) assays and array comparative genomic hybridization (array CGH).
  
  
  RESULTS
  In a series of 2871 patients for whom cytogenetic analysis was requested, 14 cases with small supernumerary marker chromosomes (sSMCs) were identified. Nine sSMCs were mosaic, and five nonmosaic. Of the nine cases with known parental origins, four were identified as de novo, and four and one were maternally and paternally inherited, respectively. Six sSMCs were identified by FISH using centromeric probes; three sSMCs were derived from chromosome 15, including two heterochromatic sSMC(15)s and a large sSMC(15) spanning 15q11.1q13.1, and three sSMCs originated from chromosome 14 or 22. Array CGH revealed two cases with derivatives of chromosome 2 and whole chromosome painting multicolor-FISH (M-FISH) identified three cases with derivatives of chromosome 6, 16, and 19, respectively. One maker chromosome in Turner syndrome was characterized as sSMC(X) by preferential application of a centromeric probe for X-chromosome. In addition, one sSMC composed of genomic materials from chromosomes 12 and 18 was identified in parallel with parental karyotype analysis that revealed the reciprocal balanced translocation.
  
  
  CONCLUSIONS
  This report is the largest study on sSMCs in Korea and expands the spectrum of sSMCs that are molecularly characterized.
authors: Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea ; Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: Woori
authors: W
authors: Jang
authors: Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea ; Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea ; Department of Laboratory Medicine, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, 222 Banpo-daero, Seocho-gu, Seoul, 137-701 Korea.
authors: Hyojin
authors: H
authors: Chae
authors: Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: Jiyeon
authors: J
authors: Kim
authors: Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: Jung-Ok
authors: JO
authors: Son
authors: Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: Seok Chan
authors: SC
authors: Kim
authors: Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: Bo Kyung
authors: BK
authors: Koo
authors: Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea ; Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: Myungshin
authors: M
authors: Kim
authors: Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea ; Catholic Genetic Laboratory Center, Seoul St. Mary's Hospital, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: Yonggoo
authors: Y
authors: Kim
authors: Department of Obstetrics and Gynecology, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: In Yang
authors: IY
authors: Park
authors: Department of Pediatrics, College of Medicine, The Catholic University of Korea, Seoul, Korea.
authors: In Kyung
authors: IK
authors: Sung
keywords: Array comparative genomic hybridization; Fluorescence in situ hybridization; Marker chromosome