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ISCN Symbols and Abbreviated Terms
Symbols and abbreviated terms used in the description of chromosomes and chromosomal abnormalities are listed below. For a detailed discussion of these terms, consult ISCN (1995): An International System for Human Cytogenetic Nomenclature, Mitelman, F (ed); S. Karger, Basel, 1995.
Consider the following when searching for chromosomal abnormalities:
| add |
additional material of unknown origin |
| approximate sign (~) |
denotes intervals and boundaries of a chromosome segment or number of chromosomes, fragments, or markers; denotes a range of number of copies of a chromosomal region when the exact number cannot be determined |
| arr |
microarray |
| arrow (-> or →) |
from - to, in detailed system |
| brackets, square ([ ]) |
surround number of cells or genome build |
| cen |
centromere |
| cgh |
comparative genomic hybridization |
| chr |
chromosome |
| cht |
chromatid |
| colon, single (:) |
break, in detailed system |
| colon, double (::) |
break and reunion, in detailed system |
| comma (,) |
separates chromosome numbers, sex chromosomes, and chromosome abnormalities, seperates locus designations |
| cp |
composite karyotype |
| decimal point (.) |
denotes sub-bands |
| del |
deletion |
| der |
derivative chromosome |
| dic |
dicentric |
| dn |
designates a chromosome abnormality that has not been inherited (de novo) |
| dup |
duplication |
| fra |
fragile site |
| h |
heterochromatin, constitutive |
| hmz |
homozygous, homozygosity; used when one or two copies of a genome are detected, but previous, known heterozygosity has been reduced to homozygosity through a variety of mechanisms, e.g. loss of heterozygosity (LOH) |
| hsr |
homogeneously staining region |
| htz |
heterozygous, heterozygosity |
| i |
isochromosome |
| idic |
isodicentric chromosome |
| ins |
insertion |
| inv |
inversion |
| mar |
marker chromosome |
| mat |
maternal origin |
| mos |
mosaic |
| p |
short arm of chromosome |
| parentheses ( ) |
surround structurally altered chromosomes and breakpoints; surround chromosome numbers, X, and Y in normal and abnormal results; surround coordinates (or nucleotide positions) in abnormal result |
| pat |
paternal origin |
| ps |
satellited short arm of chromosome |
| pter |
terminal end of the short arm |
| q |
long arm of chromosome |
| qter |
terminal end of the long arm |
| question mark (?) |
questionable identification of a chromosome or chromosome structure |
| r |
ring chromosome |
| rec |
recombinant chromosome |
| rob |
robertsinian translocation |
| s |
satellite |
| sce |
sister chromatid exchange |
| sdl |
sideline |
| seq |
sequencing |
| slant line, single (/) |
separates clones, or contiguous probes |
| stk |
satellite stalk |
| subtel |
subtelomeric region |
| t |
translocation |
| tas |
telomeric association |
| ter |
terminal (end of chromsome) or telomere |
| upd |
uniparental disomy |
| var |
variant or variable region |
In Situ Hybridization: Symbols and Abbreviations
| minus sign (-) |
loss; decrease in length; locus absent from a specific chromosome |
| plus sign, single (+) |
additional normal or abnormal chromosomes; increase in length locus present on a specific chromosome |
| plus sign, double (++) |
two hybridization signals or hybridization regions on a specific chromosome |
| multiplication sign (x) |
multiple copies of rearranged chromosomes; designates aberrant polyploidy clones in neoplasias; with number to indicate number of signals seen; multiple copies of a chromosome or chromosomal region |
| period (.) |
separates various techniques |
| semicolon (;) |
separates altered chromosomes and breakpoints in structural rearrangements involving more than one chromosome; seperates probes on different derivative chromosomes |
| FISH |
fluorescence in situ hybridization |
| ish |
in situ hybridization; when used without a prefix applies to metaphase or prometaphase chromosomes of dividing cells |
| wcp |
whole chromosome paint |
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