A novel mechanism for the origin of supernumerary marker chromosomes

Hum Genet. 1996 Mar;97(3):382-6. doi: 10.1007/BF02185778.


A ring chromosome 3 and a 47th chromosome formed by the portions of 3p and 3q distal to the r(3) breakpoints were found in a girl with mental retardation and minor facial anomalies. The supernumerary chromosome 3, rea(3), had a primary constriction inside its 3p portion (3p23) and was consistently stable both in lymphocytes and fibroblasts. In situ hybridization with alphoid probes revealed that the r(3) maintained its wild-type-centromere, whereas the rea(3) showed no alphoid-related signals. This case and a similar one recently reported demonstrate that acentric fragments can acquire a new centromere and become stable, and that supernumerary marker chromosomes can also originate by the junction of the acentric portions distal to the centric region forming a ring. The possibility of such a chromosome segregating will depend on its ability to (re)activate a new centromere.

MeSH terms

  • Adult
  • Chromosome Aberrations*
  • Chromosome Disorders*
  • Chromosome Mapping
  • Chromosomes, Human, Pair 3 / genetics*
  • Face / abnormalities
  • Female
  • Genetic Markers*
  • Humans
  • In Situ Hybridization, Fluorescence
  • Intellectual Disability / genetics
  • Karyotyping
  • Prohibitins
  • Ring Chromosomes*


  • Genetic Markers
  • PHB2 protein, human
  • Prohibitins

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