Mosaic vs. nonmosaic trisomy 9: report of a liveborn infant evaluated by fluorescence in situ hybridization and review of the literature

Am J Med Genet. 1996 Apr 24;62(4):330-5. doi: 10.1002/(SICI)1096-8628(19960424)62:4<330::AID-AJMG1>3.0.CO;2-V.


We report on a newborn infant with multiple congenital anomalies and apparent nonmosaic trisomy 9 in the blood (by conventional cytogenetic studies) who died shortly after birth. Clinical observations at birth and autopsy are compared with phenotypes of mosaic and nonmosaic trisomy 9 cases reported previously. Unlike the initial cytogenetic analysis, fluorescence in situ hybridization (FISH) studies of metaphase and interphase blood cells and skin fibroblasts detected the presence of euploid and trisomy 9 cells. These results suggest that earlier reports of trisomy 9, which relied on conventional chromosome analysis of a few metaphase cells and/or only one tissue type, may not have excluded mosaicism, and that trisomy 9 may be viable only in the mosaic state.

Publication types

  • Case Reports
  • Review

MeSH terms

  • Abnormalities, Multiple / genetics*
  • Adult
  • Autopsy
  • Chromosomes, Human, Pair 9*
  • Fatal Outcome
  • Female
  • Humans
  • In Situ Hybridization*
  • Infant, Newborn
  • Male
  • Mosaicism*
  • Trisomy*