The Principles of Clinical Cytogenetics - Extra Materials - Springer

Human Chromosome Nomenclature 53
Table 4
Selected List of Symbols and Abbreviations Used for In Situ Hybridization (ish) Nomenclature
Abbreviation
or Symbol Description
– Absent on a specific chromosome
+ Present on a specific chromosome
++ Duplication on a specific chromosome
x Precedes the number of signals seen
. Period, separates cytogenetic results from ish results
con Connected or adjacent signals
ish Refers to in situ hybridization; when used by itself, ish refers to hybridization to chromosomes
nuc ish Nuclear or interphase in situ hybridization
pcp Partial chromosome paint
sep Separated signals (which are usually adjacent)
wcp Whole chromosome paint
Note: For a complete listing of symbols and abbreviations, refer to ISCN 2005 (12).
The second cell line contains the sex chromosomes and all of the abnormalities present in the first:
47,XY,del(5)(q13q33),+8,t(9;22)(q34;q11.2)[4]/48,idem,+9,i(17)(q10)[12]/46,XY[4]
�
plus an additional copy of chromosome 9:
47,XY,del(5)(q13q33),+8,t(9;22)(q34;q11.2)[4]/48,idem,+9,i(17)(q10)[12]/46,XY[4]
�
and an isochromosome for the long arm of chromosome 17:
47,XY,del(5)(q13q33),+8,t(9;22)(q34;q11.2)[4]/48,idem,+9,i(17)(q10)[12]/46,XY[4].
�
Because this is the largest clone present (with 12 cells), it represents the mainline.
Finally, as mentioned above, the third cell line represents cells with a normal male karyotype:
47,XY,del(5)(q13q33),+8,t(9;22)(q34;q11.2)[4]/48,idem,+9,i(17)(q10)[12]/46,XY[4]
�
In the next example there are three cell lines; the stemline and two diverging sidelines.
46,XY,inv(16)(p13q22)[7]/47,sl,+22[8]/46,sdl1,–7[5]
The stemline consists of seven cells with an XX sex chromosome complement and an inverted chromosome16.
The first sideline consists of eight cells that also have an XX sex chromosome complement
and the inverted 16 (indicated by the abbreviation sl), but also have an additional chromosome 22. The
second sideline consists of five cells with an XX sex chromosome complement, the inverted 16, the
additional chromosome 22 (indicated by the abbreviation sdl1), and monosomy 7.
Thus, we see that by examining the components of a reported karyotype using the above-outlined
rules, together with the abbreviations listed in Table 3 or in the nomenclature document itself (12),
what initially might appear as an indecipherable compilation of numbers and symbols becomes a
concise, universal method of describing the results of a patient’s chromosome analysis.
FLUORESCENCE AND OTHER IN SITU HYBRIDIZATION
Recent advances in human cytogenetics include the development and application of in situ hybridization
(ish) protocols to incorporate and bind labeled, cloned DNA or RNA sequences to cytological
preparations. These techniques facilitate the localization of specific genes and DNA segments onto
specific chromosomes, ordering the position and orientation of adjacent genes along a specific chromosome,
identification of microduplications or microdeletions of loci that lie beyond the resolution of
conventional cytogenetics but manifest themselves as abnormal clinical phenotypes, and the detection
of aneuploidies involving whole chromosomes or chromosomal regions (see Chapter 17). For these
reasons, nomenclature to designate various ish applications was introduced in ISCN 1995. The symbols
and abbreviations used in ish nomenclature are listed in Table 4.