Glossary of Karyotype Report Terms and Definitions

Below is a listing of terms and definitions most commonly used in our chromosome analysis reports. 

  • Two or more cells with the same extra chromosome.
  • Three or more cells with the same missing chromosome.
  • Two or more cells with the same structural rearrangement.
  • Changes that do not meet the requirements of clonality (typically single-cell findings).
  • Can be caused by technical artifact such as chromosomes blowing out from one metaphase spread, and possibly into another.
  • Listed on reports to inform that there was a cell with some change seen during analysis but that it did not (and maybe will not) rise to the level of something that will make the karyotype abnormal.
  • Presence of two or more cytogenetically distinguishable cell lines. 
p arm:
  • Chromosome short arm.
q arm:
  • Chromosome long arm.
  • Additional material of unknown origin attached to a chromosome region or band.
del or deletion:
  • Loss of a chromosome segment.
  • Terminal - the distal side of a break is lost
  • Interstitial - created by two breaks, where the two broken edges rejoin and the intervening, acentric segment is lost. 
der or derivative:
  • Structurally rearranged chromosome generated either by a rearrangement involving two or more chromosomes or by multiple aberrations within a single chromosome.
dic or dicentric:
  • A chromosome that contains two centromeres.
dup or duplication:
  • Gain of a chromosome segment observed at the original chromosome location.
inv or inversion:
  • A single chromosome undergoes breakage and rearrangement within itself, causing a segment of a chromosome to be reversed end to end.
  • Pericentric - involves both arms of a chromosome and includes the centromere
  • Paracentric - involves only one arm of a chromosome and doe snot include the centromere
ins or insertion:
  •  Segment of one chromosome has been deleted from its normal location and inserted into another location.
i or isochromosome:
  • Unbalanced structural abnormality in which the arms of the abnormal chromosome are mirror images of each other.
mar or marker:
  • Structurally abnormal chromosome that cannot be unambiguously identified or characterized by conventional banding cytogenetics.
t or translocation:
  • Rearrangement of segments between chromosomes.
sl or stemline:
  • the most basic clone of a tumor cell population and is listed first
sdl or sideline
  • all additional clones deviating from the stemline
idem (latin word for same)
  • also used to describe the most basic clone of a tumor cell population
cp or composite
  • results based on consistent abnormalities between cells in culture 
  • the total number of cells in which the clonal changes were observed is given in square brackets