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Difference between revisions of "Cytogenetics"
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more types of probes, 3 colour
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=General= | =General= | ||
* | *Detects "large" changes (in chromosomes). | ||
** | **Conventional karyotyping has a maximum resolution 3-4 megabase pairs (3-4 million base pairs); may be less - dependent on band density.<ref>{{Ref WMSP|695}}</ref> | ||
* | *Cytogenetics is morphologic data an the interpretation has a greater degree of subjectivity vis-a-vis genetic sequencing. | ||
=Techniques (overview)= | =Techniques (overview)= | ||
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===Probe types=== | ===Probe types=== | ||
Types: | Types: | ||
*Fusion - two colour | *Fusion - usually two colours. | ||
**Two colour - two different probes with different colours, e.g. [[translocations|IGH/BCL2 translocation]]. | |||
**Two colour fusion with extra signal - similar two colour fusion.<ref name=pmid12764379>{{Cite journal | last1 = Primo | first1 = D. | last2 = Tabernero | first2 = MD. | last3 = Rasillo | first3 = A. | last4 = Sayagués | first4 = JM. | last5 = Espinosa | first5 = AB. | last6 = Chillón | first6 = MC. | last7 = Garcia-Sanz | first7 = R. | last8 = Gutierrez | first8 = N. | last9 = Giralt | first9 = M. | title = Patterns of BCR/ABL gene rearrangements by interphase fluorescence in situ hybridization (FISH) in BCR/ABL+ leukemias: incidence and underlying genetic abnormalities. | journal = Leukemia | volume = 17 | issue = 6 | pages = 1124-9 | month = Jun | year = 2003 | doi = 10.1038/sj.leu.2402963 | PMID = 12764379 | url = http://www.nature.com/leu/journal/v17/n6/full/2402963a.html }}</ref> | |||
**Three-colour where two probes (e.g. red and blue) straddle the break point. | |||
***One of the (true) translocations will have only two colours (e.g. Philadelphia chromosome). | |||
***The derivative chromosome (e.g. derivative 9 chromosome in Philadelphia chromosome cells), which may be lost, will have all three colours. | |||
***A (non-pathologic) coincidental colocalization (or overlap) of probes will consist of all three colours. | |||
*Break apart - two colour, e.g. [[translocations|c-MYC rearrangement]]. | *Break apart - two colour, e.g. [[translocations|c-MYC rearrangement]]. | ||
*Deletion/duplication (e.g. trisomy) - one colour. | *Deletion/duplication (e.g. trisomy) - one colour. | ||