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ISCN Abbreviated Terms and Symbols

Abbreviated terms and symbols used in the description of chromosomes and chromosomal abnormalities are listed below. For a detailed discussion of these terms, consult the most recent edition of "ISCN: An International System for Human Cytogenetic Nomenclature".

Term (Symbol) Description
add Additional material of unknown origin
approximate sign (-)** Denotes intervals and boundaries of a chromosome segment
c Constitutional anomaly
comma (,) Separates chromosome numbers, sex chromosomes, chromosome abnormalities
cp Composite karyotype
del Deletion
der Derivative chromosome
dic Dicentric
dmin Double minute
dup Duplication
fis Fission, at the centromere
hsr Homogeneously staining region
i Isochromosome
idem Denotes the stemline karyotype in subclones
ider Isoderivative chromosome
idic Isodicentric chromosome
inc Incomplete karyotype
ins Insertion
inv Inversion
mar Marker chromosome
minus sign (-) Loss
multiplication sign (x) Multiple copies of rearranged chromosomes
or Alternative interpretation
p Short arm of chromosome
parentheses () Surround structurally altered chromosome and breakpoints
plus sign (+) Gain
q Long arm of chromosome
qpd Quadruplication
question mark (?) Questionable identification of a chromosome or chromosome structure
r Ring chromosome
semicolon (;) Separates altered chromosomes and breakpoints in structural rearrangements involving more than one chromosome
Slant line (/) Separates clones
t Translocation
tas Telomeric association
trc Tricentric chromosome
trp Triplication

**The symbol for the approximate sign in the Mitelman database is the minus sign (-).