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© 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare www.geneticseducation.nhs.uk Conditions caused by abnormalities.

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Presentation on theme: "© 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare www.geneticseducation.nhs.uk Conditions caused by abnormalities."— Presentation transcript:

1 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 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.

2 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig. 2.1 ©Scion Publishing Ltd Child with 22q11 deletion. Note small mouth, narrow nose and upward slant of her eyes.

3 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©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)

4 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©Scion Publishing Ltd How the 1;22 translocation originated Chromosome 1 and 22 broke at the positions indicated by the arrows, and the cells DNA repair machinery rejoined the ends to form the two derivative chromosomes as shown. The derivative chromosomes are labelled der(1) and der(22).

5 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©Scion Publishing Ltd

6 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©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.

7 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©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.

8 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©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.

9 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig. Disease box 3 ©Scion Publishing Ltd (a-c) Reproduced with permission from Dr Ursula Bellugi, The Salk Institute for Biological Studies. (a) Williams-Beuren syndrome (b) Drawings by people with Williams-Beuren syndrome

10 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig. 4.3 ©Scion Publishing Ltd Photos courtesy of Dr Bert de Vries 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 5 th finger and distal brachydactyly).

11 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig. 4.8 ©Scion Publishing Ltd Example of array-CGH output

12 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©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.

13 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©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.

14 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig. 8.2 ©Scion Publishing Ltd Photo. courtesy of Dr John Yin Typical appearance of acute lymphocytic leukaemia. Small blasts with high nuclear – cytoplasmic ratio, some with prominent nucleoli.

15 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©Scion Publishing Ltd Reproduced from Molecular Cancer, 2: 30; © 2003 Duensing et al.; licensee BioMed Central Ltd Burkitts 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.

16 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare Fig ©Scion Publishing Ltd Photo. courtesy of Dr Christine Harrison 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.

17 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 45,XX,der(14;21)(q10;q10)

18 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 46,XX,t(4;15)(q2?1.3;q13)

19 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 46,XX,t(9;22)(q34;q11)

20 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare ish der(9)(ABL-),der(22)(BCRsp+conABLsp+,ABLsp+,BCRsp+)

21 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 46,X,r(X)

22 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare ins(22;9)(q11;q13q34)

23 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 46,XY.ish del(15)(q11.2q11.2)(SNRPN-)

24 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 46,XY.ish del(15)(q11.2q11.2)(SNRPN-)

25 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 46,XX.ish del(22)(q11.2q11.2)(TUPLE1-)

26 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 46,XX.ish del(22)(q11.2q11.2)(TUPLE1-)

27 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 46,X,del(X)(p21.1)

28 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare 46,XX,del(4)(p15.2p16.?2)

29 © 2009 NHS National Genetics Education and Development CentreGenetics and Genomics for Healthcare ish del(7)(q11.23q11.23)(ELN-) Williams syndrome


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