Conditions caused by abnormalities in chromosome structure This PowerPoint file contains a number of slides that may be useful for teaching of genetics concepts. You may use these slides and their contents for non-commercial educational purposes.

Fig. 2.1 ©Scion Publishing Ltd Child with 22q11 deletion. Note small mouth, narrow nose and upward slant of her eyes. Fig. 2.1 ©Scion Publishing Ltd

Fig. 2.14 ©Scion Publishing Ltd G-banded karyotypes of chromosomes There is a balanced translocation. Chromosomes 1 and 22 have exchanged segments (arrows). The translocation is described as 46,XX,t(1:22)(q25;q13) Fig. 2.14 ©Scion Publishing Ltd

Fig. 2.16 ©Scion Publishing Ltd How the 1;22 translocation originated Chromosome 1 and 22 broke at the positions indicated by the arrows, and the cell’s DNA repair machinery rejoined the ends to form the two derivative chromosomes as shown. The derivative chromosomes are labelled der(1) and der(22). Fig. 2.16 ©Scion Publishing Ltd

Fig. 2.19 ©Scion Publishing Ltd

Fig. 2.15 ©Scion Publishing Ltd G-banded karyotype She has inherited a normal chromosome 1 but her translocated chromosome 22 (arrow). She is trisomic for the portion of chromosome 1 distal to 1q25, the translocation breakpoint, and monosomic for chromosome 22 distal to 22q13. Fig. 2.15 ©Scion Publishing Ltd

Fig. 2.20 ©Scion Publishing Ltd A Robertsonian translocation The inset shows how this common type of chromosome abnormality arises. The short arms of all the acrocentric chromosomes (13, 14, 15, 21, 22) contain similar DNA. Inappropriate recombination between two non-homologous chromosomes produces the fusion chromosome, which functions as a normal single chromosome in mitosis. The small acentric fragment comprising the two distal short arms is lost. Fig. 2.20 ©Scion Publishing Ltd

Fig. 2.21 ©Scion Publishing Ltd During meiosis I matching chromosome segments pair. If one chromosome has an inversion compared to its homolog, they usually form a looped structure. Fig. 2.21 ©Scion Publishing Ltd

Fig. Disease box 3 ©Scion Publishing Ltd (a) “Williams-Beuren syndrome” (b) “Drawings by people with Williams-Beuren syndrome” Fig. Disease box 3 ©Scion Publishing Ltd (a-c) Reproduced with permission from Dr Ursula Bellugi, The Salk Institute for Biological Studies.

A child with multiple congenital abnormalities suggestive of a chromosome abnormality She has severe mental retardation, growth retardation, microcephaly and dysmorphism of the face and hands (epicanthic folds, hypertelorism, arched eyebrows, low-set ears, short philtrum, open mouth appearance, full lips, irregular position of the lower teeth, clinodactyly of the 5th finger and distal brachydactyly). Fig. 4.3 ©Scion Publishing Ltd Photos courtesy of Dr Bert de Vries

Fig. 4.8 ©Scion Publishing Ltd Example of array-CGH output Fig. 4.8 ©Scion Publishing Ltd

Fig. 4.14 ©Scion Publishing Ltd 22q11 metaphase FISH The green spots are a control probe, used to identify the two copies of chromosome 22 and confirm that hybridization has taken place. The red spots are the TUPLE1 probe. Only one of the two copies of chromosome 22 contains the sequence that hybridizes to this probe. Fig. 4.14 ©Scion Publishing Ltd

Fig. 7.14 ©Scion Publishing Ltd The 15q11q13 deletion in Prader-Willi or Angelman syndrome patients is sometimes just visible under the microscope in a standard cytogenetic preparation. In most cases a molecular test (FISH or PCR) is needed to make the diagnosis. Fig. 7.14 ©Scion Publishing Ltd

Typical appearance of acute lymphocytic leukaemia Typical appearance of acute lymphocytic leukaemia. Small blasts with high nuclear – cytoplasmic ratio, some with prominent nucleoli. Fig. 8.2 ©Scion Publishing Ltd Photo. courtesy of Dr John Yin

Burkitt’s lymphoma (a) Histology, and (b) a karyotype showing the characteristic 8;14 translocation. Additional chromosome abnormalities are also present, as is usually the case in neoplasia. Fig. 12.5 ©Scion Publishing Ltd Reproduced from Molecular Cancer, 2: 30; © 2003 Duensing et al.; licensee BioMed Central Ltd

Metaphase with TEL-AML1 fusion The green signal is on the normal chromosome 12, one red signal is in the normal chromosome 21 and one is on the derived chromosome 12. The yellow TEL-AML1 fusion signal is on the derived chromosome 21. Fig. 12.10 ©Scion Publishing Ltd Photo. courtesy of Dr Christine Harrison

45,XX,der(14;21)(q10;q10)

46,XX,t(4;15)(q2?1.3;q13)

46,XX,t(9;22)(q34;q11)

ish der(9)(ABL-),der(22)(BCRsp+conABLsp+,ABLsp+,BCRsp+)

46,X,r(X)

ins(22;9)(q11;q13q34)

46,XY.ish del(15)(q11.2q11.2)(SNRPN-)

46,XY.ish del(15)(q11.2q11.2)(SNRPN-)

46,XX.ish del(22)(q11.2q11.2)(TUPLE1-)

46,XX.ish del(22)(q11.2q11.2)(TUPLE1-)

46,X,del(X)(p21.1)

46,XX,del(4)(p15.2p16.?2)

ish del(7)(q11.23q11.23)(ELN-) Williams syndrome