title: Acquired X-chromosome aneuploidy in children with acute lymphoblastic leukemia.
abstract: BACKGROUND
  A cytogenetic study of 75 consecutive children with ALL revealed a normal karyotype, a low hyperdiploid karyotype (including 47-50 chromosomes), and a high hyperdiploid karyotype (including > 50 chromosomes) in 10, 12, and 33 patients, respectively. An acquired extra X-chromosome was detected at diagnosis by conventional cytogenetics in 29 (88%) of 33 children with a high hyperdiploid karyotype and in 4 (33%) of 12 children with a low hyperdiploid karyotype. X-chromosome aneuploidy was retrospectively studied by fluorescence in situ hybridization (FISH) in eight and 20 patients with a normal and a hyperdiploid karyotype, respectively.
  
  
  METHODS
  A classical cytogenetic study was performed according to standard methods. FISH with the centromeric probe specific to X-chromosome was used to study interphase cells of bone marrow or blood samples.
  
  
  RESULTS
  An extra X-chromosome was found by FISH in all 13 patients with a high hyperdiploid or tetraploid, in 6 of 7 patients with a low hyperdiploid, and in none with a normal karyotype. Two children with a normal karyotype displayed monosomy X. Altogether, 57.3% of newly diagnosed children displayed X-chromosome aneuploidy.
  
  
  CONCLUSIONS
  Out study indicates that X-chromosome aneuploidy may be the most common chromosome abnormality in childhood ALL. It can be detected in nearly all children with a high hyperdiploid karyotype and up to one-half of the patients with a low hyperdiploid karyotype. FISH with an X-chromosome centromeric probe is a rapid and simple tool to detect an abnormal clone at diagnosis in the majority of children with ALL and is useful in confirming remission in these patients.
authors.affiliation: Chromosome and DNA Laboratory, Kuopio University Hospital, Finland. kristiina.heinonen@kuh.fi
authors.forename: K
authors.initials: K
authors.lastname: Heinonen
authors.forename: E
authors.initials: E
authors.lastname: Mahlamäki
authors.forename: P
authors.initials: P
authors.lastname: Riikonen
authors.forename: R L
authors.initials: RL
authors.lastname: Meltoranta
authors.forename: J
authors.initials: J
authors.lastname: Rahiala
authors.forename: M
authors.initials: M
authors.lastname: Perkkiö
mesh_terms: D000293:Adolescent; D000782:Aneuploidy; D002648:Child; D002675:Child, Preschool; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D015994:Incidence; D007223:Infant; D007621:Karyotyping; D008297:Male; D054198:Precursor Cell Lymphoblastic Leukemia-Lymphoma / Q000235:genetics*; D012189:Retrospective Studies; D014960:X Chromosome