Errata

No published book is free of mistakes. For a broader audience, errata are regularly published on this page as well as with the corresponding chapter within ISCN Online and as a Free Access article in the Karger Journal Cytogenetic and Genome Research.

3 Symbols, Abbreviated Terms, and General Principles

upd	Uniparental disomy (8.4, 14.2.1)

8 Numerical Chromosome Abnormalities

8.3 Autosomal Abnormalities

48,XY,+21c,+21 An acquired extra chromosome 21 in a patient with Down syndrome.

46,XY,+21c,–21 Acquired loss of one chromosome 21 in a patient with Down syndrome.

9 Structural Chromosome Rearrangements

9.1 General Principles

46,XX,inv(3)(q21q26.2) An inversion of one chromosome 3. There is no need to indicate that one chromosome 3 is missing, i.e., the karyotype should not be written 46,XX,–3,+inv(3).

9.2.1 Additional Material of Unknown Origin

46,XY,add(12)(q13)
46,XY,add(12)(pter→q13::?) Additional material of unknown origin replaces the segment 12q13qter.

9.2.3 Derivative Chromosomes

47,XX,t(9;22;6)(q34;q11.2;p21),+der(22)t(9;22;6) A three-way translocation between chromosomes 9, 22, and 6 is present along with an additional derivative chromosome 22 from this three-way translocation.

46,XY,der(9)t(9;22)(q34;q11),+22,der(22;22)(22pter→22q11::9q34→9qter::9qter→9q34::22q11→22pter) An isochromosome for the derivative chromosome 22 generated by a t(9;22), i.e., an isochromosome for the long arm of a Ph chromosome. There are also two normal copies of chromosome 22 and the derivative chromosome 9 generated by a t(9;22).

53,XX,…,+der(?)t(?;9)(?;q22),+r,+mar,dmin

9.2.5 Duplications

46,XX,dup(1)(p31p34)
46,XX,dup(1)(pter→p31::p31→p34::p31→qter) or dup(1)(pter→p34::p31→p34::p31→pter) Duplication of the segment between bands 1p34 and 1p31, in reversed orientation relative to pter and qter. Note that only the detailed form will clarify the location of the duplicated segment.

9.2.8 Homogeneously Staining Regions

46,XX,der(1)ins(1;7)(q21;p21p11.2)hsr(1;7)(q21;p11.2)
46,XX,der(1)(1pter→1q21::hsr::7p11.2→7p21::1q21→1qter) Insertion of the segment 7p21p11.2 into the long arm of chromosome 1 with breakage and reunion at band 1q21. The derivative chromosome also contains an hsr at the interface between the recipient and donor chromosomes. The hsr is located proximal to the segment inserted from chromosome 7.

46,XX,der(1)ins(1;7)(q21;p21p11.2)hsr(1;7)(q21;p21)
46,XX,der(1)(1pter→1q21::7p11.2→7p21::hsr::1q21→1qter) Insertion of the segment 7p21p11.2 into the long arm of chromosome 1 with breakage and reunion at band 1q21. The derivative chromosome also contains an hsr at the interface between the recipient and donor chromosomes. The hsr is located distal to the segment inserted from chromosome 7.

9.2.9 Insertions

The symbol ins is used for insertions. The orientation of the inserted segment is indicated by the order of the bands of the inserted segment with respect to the centromere. For clarity, the use of the detailed form is recommended.

9.2.17.1 Reciprocal Translocations

46,XX,t(5;14;9)(q13q23;q24q21;p12p23)
46,XX,t(5;14;9)(5pter→5q13::9p12→9p23::5q23→5qter;14pter→14q21::5q13→5q23::14q24→14qter;9pter→9p23::14q21→14q24::9p12→9qter) Reciprocal six-break translocation of three interstitial segments. The segment between bands 5q13 and 5q23 on chromosome 5 has replaced the segment between bands 14q21 and 14q24 on chromosome 14, the segment 14q21q24 has replaced the segment between bands 9p23 and 9p12 on chromosome 9, and the segment 9p23p12 has replaced the segment 5q13q23. The orientations of the segments in relation to the centromere are apparent from the order of the bands. The segments 9p23p12 and 14q21q24 are inverted.

11 Neoplasia

11.1.4 Stemline, Sideline and Clonal Evolution

47,XX,inv(6)(p21q25),+12[17]/50,sl,–inv(6),+7,+8,+9,+mar[11]
47,XX,inv(6)(p21q25),+12[17]/50,idem,–inv(6),+7,+8,+9,+mar[11] The inv(6) present in the stemline has not been found in the sideline with 50 chromosomes. The breakpoints in the inv(6) need not be repeated. Note that there is monosomy 6 in the sideline. If the sideline was disomic for chromosome 6 then it would be written: 50,sl,+6,–inv(6),+7,+8,+9,+mar[11] or 50,idem,+6,–inv(6),+7,+8,+9,+mar[11]

11.2 Modal Number

81<3n>,XXX,+X,+X,+X,+X,+X,+1,+1,+3,+3,+14,+14,+14,–15,+21 A tumor in a female shows 81 chromosomes but is reported relative to triploid since most chromosomes are trisomic and this is biologically significant for the disease in question, although the count is in the near-tetraploid range.

13 In situ Hybridization

13.2.1 Normal Signal Pattern

46,XX.ish 17p11.2(RAI1×2),21q21.3(D21S259/D21S341/D21S342×2) A normal female. The RAI1 locus on chromosome 17 and the Down syndrome critical region on chromosome 21 are both present in the normal copy number (two copies) as determined by ish with a locus-specific probe. All loci of the contig probe are listed.

13.2.3 Abnormal Signal Patterns with Multiple Probes

46,X,?i(Y)(p10).ish idic(Y)(q11)(DYZ3+,DYZ1–,DYZ3+) A presumed isochromosome for the short arm of Y was shown by ish to have two centromeres and no heterochromatin.

46,XX[20].ish t(12;21)(p13;q22)(ETV6+,RUNX1+;RUNX1+,ETV6+)[5] Normal female chromosomes in an oncology sample which was also tested by metaphase FISH using a dual-fusion probe and found to have an ETV6-RUNX1 gene fusion from a cryptic reciprocal translocation between chromosomes 12 and 21.

46,X,r(X).ish r(X)(p22.3q21)(KAL+,DXZ1+,XIST+,DXZ4–) A ring X was further defined by ish as containing the short arm marker KAL1, the X alpha-satellite DXZ1 and the XIST gene on the long arm. It does not include DXZ4 at Xq24.

47,XY,+der(4)t(4;11)(p34;q13),t(4;11)[20].ish der(4)(3′KMT2A+),t(4;11)(3′KMT2A+;5′KMT2A+,3′KMT2A–)[5] A male karyotype with a t(4;11) plus an extra copy of the der(4). There is a 3′KMT2A signal on both copies of the der(4). There is a 5′KMT2A signal on the der(11) component of the t(4;11).

13.2.4 Abnormal Mosaic and Chimeric Signal Patterns with Single or Multiple Probes

ish 21q21.3(D21S259/D21S341/D21S342×3)[20]/21q21.3(D21S259/D21S341/D21S342×2)[30] A mosaic female with three chromosomes 21 present, each with a single copy of the Down syndrome critical region, in 20 of 50 metaphases analysed as determined by ish with a locus-specific probe. All loci of the contig probe are listed in the nomenclature.

13.3.3 Abnormal Interphase Signal Pattern

nuc ish(DXZ1,DYZ3)×1[34/50]/(DXZ1×1,DYZ3×0)[12/50]/(DXZ1×1,DYZ3×2)[6/50] One copy of X and one copy of Y in 34 of 50 nuclei, in addition to 12 nuclei with a single X and six nuclei with one X and two Y chromosomes. For determining the sex chromosome complement of an individual, an exception is made to include the normal complement of two sex chromosomes.

14 Microarrays

14.1 Introduction

Microarray-based chromosome analysis is principally an adjunct to traditional chromosome analysis and FISH; for prenatal and postnatal analysis, it has become the laboratory method of choice for definitive identification of chromosome abnormalities. It is increasingly used in cancer studies either as a stand alone test or in combination with FISH. Microarray nomenclature includes the genomic coordinates for banded chromosomes which are defined in the translation tables provided by NCBI (hg19/GRCh38, http://hgdownload.cse.ucsc.edu/goldenPath/hg19/database/cytoBand.txt.gz and hg38/GRCh38, http://hgdownload.cse.ucsc.edu/goldenPath/hg38/database/cytoBand.txt.gz). Platforms differ and evolve; coordinates provided reflect this and are provided only for guidance.

14.2.4 Multiple Techniques

46,X,der(Y)t(X;Y)(p22.33;q12).arr[GRCh37] Xp22.33(701_2,679,502)×3,Xp22.33p22.2(2,709,521_15,955,588)×2,Yq11.221q11.23(16,139,805_27,177,529)×0 Karyotype and microarray analyses show a single copy gain of the X chromosome from two regions of Xp and loss of the long arm of the Y chromosome, resulting from an unbalanced translocation between the short arm of the X chromosome and the long arm of the Y distal to Yq11.221. The two regions of Xp are shown separately because the gain of the pseudoautosomal region results in three total copies and the gain proximal to the pseudoautosomal region results in two total copies.

14.2.5 Mixed Cell Populations and Uncertain Copy Number

ish mos del(2)(q11.2q13)(RP11-478D22–)[10]/2q12.1(RP11-478D22+)[25].
arr[GRCh38] 2q11.2q13(100982729_112106760)×1[0.4] FISH and microarray analyses show a mosaic deletion in the long arm of chromosome 2. By microarray approximately 40% of cells have the deletion.

47,XY,+mar.ish der(2)(p11.2q13)(RP11-478D22+)[5]/2q12.1(RP11-478D22+)[25].arr[GRCh38] 2p11.2q13(90982729_112106760)×3[0.15] Microarray and FISH analyses demonstrate a mosaic marker chromosome derived from chromosome 2. By microarray approximately 15% of cells have 3 copies of the defined region.

14.2.7 Complex Array Results

arr 17p13.3q11.2(1,207,467_28,236,645)cha[0.5] Microarray analysis shows multiple changes of copy number, between 1 and ∼4, affecting most of the short arm of chromosome 17. Chromoanasynthesis was evident in approximately 50% of the sample.

14.2.8 Polar Bodies

arr cht(13,14)×2,(18)×0,(21)×2 Polar body 2 has gain of one chromatid each for 13, 14 and 21, and has lost the chromatid 18 using microarray.

15 Region-Specific Assays

15.2 Examples of RSA Nomenclature for Normal and Aneuploidy

rsa(X)×2,(13,18)×2,(21)×2∼3 Abnormal copy number result for chromosome 21 showing two to three copies for the whole chromosome 21 (mosaic trisomy) in a female using a region-specific assay. For clarity, the normal disomic states for chromosomes 13, 18, and X may be included in the nomenclature when tested.